Paediatric CT Exposure Practice
in the
Federal Republic of Germany
Results of a Nation-wide Survey in 2005/06
M. Galanski, H.D. Nagel, G. Stamm
ii
Business Addresses of the Authors
Prof. Dr. med. Michael Galanski
Zentrum Radiologie der MHH
Diagnostische Radiologie
Carl-Neuberg-Straße 1
D-30625 Hannover
Dr. rer. nat. Hans Dieter Nagel
Philips Medizin Systeme GmbH
Wissenschaftliche Abteilung
Röntgenstr. 24
D-22335 Hamburg
Dr. rer. nat. Georg Stamm
Zentrum Radiologie der MHH
Experimentelle Radiologie
Carl-Neuberg-Str. 1
30625 Hannover
mail: [email protected]
mail: [email protected]
mail: [email protected]
The survey was conducted on behalf of the Ministry of Environment, Conservation and Reactor Safety (project StSch 4470
”Investigation of representative data on the patient’s exposure resulting from frequent paediatric CT examinations for establishing
diagnostic reference levels”).
The content of the report in its present form was co-ordinated with the working group ”Paediatric Radiology” of the German
Roentgen Society.
The report represents the views and opinions of the authors and does not necessarily represent the opinion of the Ministry of
Environment, Conservation and Reactor Safety.
Layout:
Deadline:
Translation:
H. D. Nagel, Hamburg, typeset on Apple Macintosh with Adobe PageMaker
Nov. 30, 2006
H. D. Nagel, P. C. Shrimpton (English), and J.-F. Valley (French)
iii
Table of Contents
Summary ....................................................................................................................................... 1
Résumé ........................................................................................................................................... 2
1. Introduction .............................................................................................................................. 3
2. Organisation of the Survey ...................................................................................................... 4
3. Dosimetry .................................................................................................................................. 5
3.1. Weighted CTDI .................................................................................................................. 5
3.2. Volume CTDI ..................................................................................................................... 6
3.3. Dose-Length Product ......................................................................................................... 6
3.4. Effective Dose .................................................................................................................... 6
4. Results ........................................................................................................................................ 9
4.1. General Results .................................................................................................................. 9
4.1.1 Phase I ....................................................................................................................................................... 9
4.1.2 Phase II ...................................................................................................................................................... 9
4.2. Dosimetric Results ........................................................................................................... 12
4.3. Detailed Results ............................................................................................................... 12
4.3.1 Manual settings vs. automatic dose control ............................................................................................ 12
4.3.2 Overranging effects ................................................................................................................................. 12
4.3.3 Age-specific dose adaptation ................................................................................................................... 13
4.3.4 Use of reduced tube potential .................................................................................................................. 17
4.3.5 Comparison with other surveys ............................................................................................................... 18
5. Discussion ................................................................................................................................ 19
6. Reference Values, Feedback Action ...................................................................................... 23
6.1. Proposal for Diagnostic Reference Values ....................................................................... 23
6.2. Comparison with other Reference Values ........................................................................ 23
6.3. Feedback Action .............................................................................................................. 24
7. Recommendations ................................................................................................................... 25
References.................................................................................................................................... 27
Appendix .......................................................................................................................... I - XXIII
iv
Summary
Summary
A nation-wide survey of exposure practice in paediatric
CT was conducted in Germany during the period from
September 2005 until May 2006 on behalf of the ministry
for environmental protection, conservation and nuclear
safety. The survey was based on questionnaires that were
first sent to 1640 users of CT scanners installed in hospitals and private practices, asking for the frequencies of
five types of examination, subdivided into five age groups.
In a subsequent second survey, a selected number of 72
users, responsible for about two thirds of the annual paediatric CT examinations reported in phase I, were asked
for detailed dose-relevant data (scanner data, scan protocols, examination-related data and examination frequencies). These data were used for individualised dose assessments, depending on the type of scanner and age of
the patient.
With return rates of 40% in the first part and 58% in the
second part of the survey, representative results could be
obtained for the five most frequent types of paediatric CT
examination. The most essential findings are:
• The percentage of paediatric CT examinations was in
the order of only 1% of all CT and thus much smaller
than elsewhere (e.g. 6.5% for USA)
• The most frequent type of examination was brain
(52%), followed by chest (17%) and entire abdomen
(7%); other types of examination were quite rare (less
than 5%).
• The age distribution for paediatric CT examinations
was almost uniform (0 to 5 years: 40%, 6 to 10 years:
28%, 11 to 15 years: 32%).
• The majority of paediatric CT examinations were conducted in university institutions and with the latest CT
technology (multi-slice spiral scanners with solid state
detectors and dose display, often also equipped with
devices for automatic dose control).
• Exposure settings were generally adapted to the age or
weight of the patients.
• On average, the adaptation was made in a moderate
fashion that is in accordance with specific studies on
the topic and tailored more with respect to radiologists’
impression of subjective noise than to measured image
noise.
• Devices for automatic dose control (ADC) were available on roughly 50% of scanners, but were not regularly used; compared with manually adapted dose settings, dose values resulting from the use of ADC devices were slightly to significantly higher.
• Patient-size dependent adaptation of exposure settings
resulted in a significant dose reduction in terms of
CTDIvol; with respect to effective dose, however, dose
was reduced to a lesser extent or even not at all if the
increased risk for induction of malignant tumours in
children and newborn was taken into account.
• In comparison with the UK CT survey for 2003, similar results were found for brain examinations, whereas
doses for chest examinations were significantly lower.
Based on the results of this survey, proposals have been
made for diagnostic reference levels that refer to the third
quartiles of the observed dose distributions. In addition,
feedback was given to all participants of the survey in
such a way that the doses resulting from their scan protocol settings could be benchmarked against the proposed
reference dose values.
1
2
Résumé
Résumé
Une enquête nationale concernant la pratique des examens
tomodensitométriques chez les enfants a été effectuée
durant la période de septembre 2005 à octobre 2006 sur
mandat du Ministère fédéral pour l’environnement, la
protection de la nature et la sécurité des réacteurs
nucléaires. L’enquête a d’abord consisté en l’envoi d’un
questionnaire à 1640 exploitants d’installations de
tomodensitométrie dans les hôpitaux et les cabinets privés.
Il y était demandé des indications concernant les fréquences pour 5 types d’examens, ventilés en 5 groupes
d’âge. Dans une deuxième étape on s’est adressé à 72
institutions, représentant plus des deux tiers des examens
annuels tomodensitométriques en pédiatrie, pour obtenir
des données dosimétriques détaillées (indication sur
l’installation, protocole d’examen, données liées aux
examens, fréquence de ceux-ci). A l’aide des indications
de chaque protocole, on a calculé les valeurs individuelles de dose en fonction du type de l’installation et du groupe
d’âge.
Les taux de réponse ont été de 40 % dans la première phase
et de 58 % dans la seconde, autorisant la détermination de
résultats représentatifs pour les examens les plus courants
de pédiatrie. Les conclusions les plus importantes de
l’enquête sont les suivantes:
• La part des examens pédiatriques à l’ensemble des
examens tomodensitométriques s’est établie à 1%, ce
qui est sensiblement plus faible que le taux rencontré
dans d’autres pays (par exemple de 6,5% aux USA).
• Le type d’examen le plus courant a été l’examen du
cerveau (52%), suivi par le thorax (17%) et l’abdomen
complet (7%) ; les autres types d’examen ont été par
contre rare (moins de 5%).
• Les groupes d’âge de 0 à 5 ans, de 6 à 10 ans et de 11 à
15 ans ont présenté des taux proches, de 40%, 28% et
32%.
• Les examens pédiatriques de tomodensitométrie ont été
réalisés principalement sur des installations universitaires et avec la technologie la plus récente (tomodensitomètres hélicoïdaux à barrettes multiples, à base de
semi-conducteurs, et indication de dose, souvent avec
également réglage automatique du courant).
• Les paramètres d’exposition ont été généralement
adaptés à la classe d’âge et au poids du patient.
• L’adaptation en question a été en moyenne modérée,
en accord avec les résultats des études dédicacées à ce
thème. Ainsi l’adaptation se base moins sur le bruit
objectif mesuré que sur l’impression subjective de bruit
perçue par l’observateur.
• Le réglage automatique du courant, disponible sur à
peu près la moitié des installations, n’a été utilisé que
partiellement et a conduit en moyenne à des doses
légèrement, et dans certains cas significativement, plus
hautes que celles obtenues avec une adaptation manuelle des paramètres d’exposition.
• L’adaptation des paramètres d’exposition au patient a
conduit à une réduction significative de la dose appréciée par la CTDIvol ; les réductions, appréciées par la
dose efficace, ont été plus faibles et ont même disparu,
si l’on tient compte de l’augmentation du risque d’induction de tumeurs malignes pour les jeunes années.
• Les résultats de l’enquête ont indiqué des valeurs pour
les examens du cerveau de même niveau que celles de
l’enquête anglaise de 2003, mais des valeurs significativement plus faibles pour le thorax.
Sur la base des résultats de la présente enquête, des valeurs
dosimétriques de référence ont été établies, basées sur le
3ème quartile de la distribution des doses. En outre un retour d’information a été donné à tous les participants à
l’enquête (« action de feedback») sur la base duquel le
centre est à même de comparer la hauteur des doses qu’il
délivre aux valeurs de référence proposées.
1. Introduction
1. Introduction
Notwithstanding its proven diagnostic benefits, computed
tomography leads to an increased radiation exposure of
patients. New and improved imaging techniques enabled
by the introduction of multi-slice CT have further increased
the attractiveness of CT, resulting in increased examination frequencies. Consequently in a number of countries,
such as Germany (BfS 2006), CT now contributes more
than 50% of the radiation exposure of the population that
results from diagnostic medical procedures.
In February 2001, a series of articles was published in the
American Journal of Roentgenology (Rogers 2001, Brenner et al. 2001, Paterson et al. 2001), indicating that the
majority of paediatric CT examinations were made with
the same exposure settings that are used for adults, despite the fact that the x-ray beam is attenuated less by infants and children. The radiation exposure thus resulting
is not only unnecessarily high, but, due to the reduced
diameter of children, the mean absorbed doses are even
higher than for adults.
Since then, numerous recommendations have been published on how to adapt exposure settings in accordance
with patient size, weight or age (e.g. Huda et al. 2000,
Donelly et al 2001, Honnef et al. 2004). In addition, all
major CT manufacturers now offer devices for automatic
dose control (ADC) that automatically adapt the exposure
settings to match the attenuating properties of the patient
(ImPACT 2005). However, both the dose recommendations and the characteristics of the ADC devices vary
greatly, making it difficult for the casual user to profit from
these developments and innovations.
In Germany, a number of CT-related projects have been
undertaken since 1999 when the ‘Concerted Action Dose
Reduction in CT’ was founded. Among them were two
nation-wide surveys of CT exposure practice in 1999 (single-slice CT, Galanski et al. 2000) and 2002 (multi-slice
CT, Brix et al. 2003). These have served as the basis for
dose recommendations (e.g. diagnostic reference levels,
BfS 2003) that have been established in the meantime.
However, no dedicated data were collected with respect
to the application CT in paediatrics. As a consequence, a
project was advertised for bids in 2005 by the Federal
Radiation Protection Office to conduct a dedicated survey of CT exposure practice in paediatric CT.
The aims of this study are manifold:
• obtain data on the distribution and frequency of paediatric CT examinations;
• document the current status of paediatric CT;
• investigate whether and how exposure settings are
adapted to patient’s age;
• generate specific diagnostic reference dose levels.
This report presents the results of this new survey. In the
next chapter, a description is given of how the survey was
organised and conducted. Chapter 3 outlines how dose
values were derived from the reported exposure parameters. The results of this survey are presented in chapter 4
and discussed in chapter 5. A proposal for diagnostic reference values for paediatric CT examinations and the feedback given to the participants of this survey are presented
in chapter 6. In chapter 7, a number of practical recommendations are given on how to optimise examination
technique. Finally, comprehensive statistical data are compiled in the appendix.
3
4
2. Organisation of the survey
2. Organisation of the Survey
The survey was organised in two consecutive phases:
• In phase I, a total of 1640 radiologists working in
university, public and private hospitals, as well as in
private radiological practices, were asked to provide
the following data concerning annual frequencies of
CT examination: the total number of examinations for
all patients; and for paediatric patients up to 10 years,
subdivided into five age groups (premature infants,
newborn, up to 1 year, up to 5 years, up to 10 years)
and five types of examination (brain, chest, upper
abdomen, pelvis, entire abdomen). The principal aim
of this activity was to identify institutions with significant annual frequencies of paediatric CT in order to
reduce efforts in the second, more detailed phase of
the survey whilst nevertheless ensuring that the majority
of paediatric CT examinations conducted in Germany
were represented. Addresses were taken either from the
head physician register of the German Roentgen Society
or from the membership register of the professional
association of German radiologists. The questionnaire
used for this phase is shown in the appendix (fig. A1).
• In phase II, a total of 72 institutions, collectively responsible for 68% (i.e. two thirds) of the annual paediatric CT examinations reported in phase I, were asked
to provide detailed protocol data for the paediatric CT
examinations carried out on their scanners. Only those
institutions reporting at least 100 paediatric CT examinations per year in phase I of the survey were included
in phase II. In contrast to the first phase, the age group
from 11 to 15 years was included, while premature
infants and newborn were combined into a single age
group. As a consequence of the results obtained from
phase I, the range of examinations involved was also
somewhat altered: spine and facial bone examinations
were added, whereas upper abdomen and pelvis were
discarded, since the relative frequencies of these latter
two types of examination were too small. The questionnaire with the parameters requested is shown in the
appendix (fig. A2). Based on the experience from the
preceding surveys, a detailed instruction sheet was sent
with the questionnaire in order to minimise the rate of
incorrect data (fig. A3).
The data in the returned questionnaires were checked for
completeness and consistency, thereby making use of some
redundancies in the data collected (e.g. exposure settings
as well as dose values indicated at the scanner’s console).
If necessary, additional requests were sent to the participants, either to supplement incomplete data, correct inconsistent data or clarify ambiguous data.
3. Dosimetry
3. Dosimetry
Dose calculations were made in a manner similar to data
evaluation for the two preceding German CT surveys in
1999 and 2002 (Galanski et al. 2001, Brix et al. 2003).
The algorithms, dose relevant scanner data and conversion coefficients used were as described in the textbook
‘Radiation Exposure in Computed Tomography’ (Nagel
et al. 2002) and updated in the recent version of the CT
dose calculation software CT-Expo (Stamm and Nagel
2002). However, in order to meet the particular requirements for multi-slice scanners and paediatric patients, a
few major modifications were necessary:
• Firstly, with the advent of scanners capable of acquiring an increasingly large number of slices simultaneously, overranging effects (i.e. the elongation of the
scan range in spiral scan mode to enable data interpolation at the beginning and at the end of the scan) could
no longer be neglected. This applies in particular to
paediatric examinations with relatively short scan
ranges, where the percentage increase in dose-length
product (DLP) is relatively large. A correction formalism (Nagel 2005) as implemented in the CT-Expo software (version 1.4 and later) was used to account for
overranging effects.
• Secondly, in order to calculate CTDIvol values that give
realistic estimates of organ dose and allow comparison
of results with those from other surveys (Shrimpton et
al. 2005), calculations for all age groups up to 10 years
were based on CTDI values relating to the smaller
standard CT dosimetry phantom (head phantom). These
CTDI values account for the smaller patient diameter,
but apply only if the scan was made in head scanning
mode. Since paediatric CT examinations in the trunk
region are usually carried out in body scanning mode,
specific dosimetry was needed for those scanners that
apply different beam filtration in head and body mode
in order to obtain CTDI data for the smaller 16 cm phantom in body scanning mode. Such data were established
for a Somatom Sensation 4 (representative for Siemens
scanners) and a LightSpeed 16 (representative for GE
scanners).
• Thirdly, since conversion coefficients for the calculation of organ doses and effective doses were available
only for a six week old infant (‘BABY’) and a seven
year old child (‘CHILD’) (Zankl et al. 1993), further
effort was required in order to allow the computation
of effective dose for all age groups involved in this
study. This was achieved by careful analysis of the
publication by Khursheed et al. (2002). As a result, a
set of correction factors was derived that could be applied to the effective doses calculated for adults for the
scan protocol parameters used for the respective paediatric age group.
Dose calculations were made for all relevant CT dose
descriptors in the following way:
3.1. Weighted CTDI
The ‘Weighted Computed Tomography Dose Index’
(CTDIw, unit: mGy) is calculated according to
 U 
CTDIw , H / B = n CTDIw , H / B ⋅ 

 Uref 
2.5
⋅ I ⋅ t ⋅ kOB
(3.1)
where nCTDIw,H/B is the normalised weighted CTDI (unit:
mGy/mAs) for head and body scanning mode (H and B),
respectively; U (in kV) is the tube potential applied; Uref
(in kV) is the reference tube potential to which the dose
data for the particular scanner refer; I · t is the electrical
tube load (mAs product) per rotation; and kOB is the
overbeaming correction factor that accounts for the portion of the beam that is not used for imaging purposes.
Overbeaming correction is achieved by
kOB =
( N ⋅ h)ref ⋅ ( N ⋅ hcol + dz )
N ⋅ hcol ⋅ (( N ⋅ h)ref + dz )
(3.2)
where (N·h)ref is the reference beam width to which the
dose data for the particular scanner refer; N·hcol is the actual beam width for the scan protocol; and dz is the
overbeaming parameter that describes the effective width
of the unused portion of the dose profile (typically 3 mm,
dependent on the type of scanner).
In order to distinguish between CTDIw values in body scanning mode that refer either to the smaller 16 cm or the
larger 32 cm phantom, CTDI values are labelled as
CTDIw16 and CTDIw32, respectively.
5
6
3. Dosimetry
3.2. Volume CTDI
The ‘Volume Computed Tomography Dose Index’
(CTDIvol, unit: mGy) is defined as
CTDIvol =
CTDIw
p
istic dose estimates, but also to allow comparison with
the quantity shown at the dose display.
The pitch definition used here refers to the revised IEC
standard 60601-2-44 ed. 2.0 (IEC 2001):
( 3.3)
i.e. CTDIvol is the pitch-corrected weighted CTDI. CTDIvol
is equal to the average absorbed dose (the ’intensity’ of
the irradiation) inside the scan range and provides a fair
estimate of the dose to organs that are entirely located
inside the scan range. CTDIvol is displayed at the scan console of all newer scanners. Whether it refers to values of
head or body CTDI depends solely on the selected scan
mode (head or body), and not on the size of the patient.
Therefore the dose to paediatric patients in examinations
of the trunk region, based on the CTDIvol from the scanner’s dose display, is under-estimated by a factor two to
three. Consequently, values were calculated for both
CTDIvol16 and CTDIvol32 in order not only to provide real-
p =
TF
N ⋅ hcol
(3.4)
where TF is the table feed per rotation and N·hcol is the
actual beam width for the scan protocol. This universal
pitch definition, resulting in typical pitch factors of
between 0.5 and 2.0, is now used for most scanners,
whereas older MSCT scanners often display pitch factors
(‘volume pitch’ or ‘detector pitch’) that are N times larger
(N = number of slices acquired simultaneously).
3.3. Dose-Length Product
The ‘Dose-Length Product’ (DLP, unit: mGy·cm) is obtained from the CTDIvol and the scan length via
DLP = CTDIvol ⋅ Ltot
( 3.5)
∆L = N ⋅ hcol ⋅ ( mOR ⋅ p + bOR )
( 3.7)
where mOR and bOR are the overranging parameters that
express the pitch dependence of overranging effects.
where Ltot is the total scan length (in cm!). The scan length
information, given explicitly or implicitly in the images
and on most scanner consoles, refers only to the position
of the first and the last slice. Therefore one half of a (reconstructed) slice width hrec has to be added at each end of
the scan range to get at least the length of the range that is
represented by the set of images obtained from the scan.
If the examination is carried out in spiral scanning mode,
overranging effects also imply an additional length ∆L.
Therefore the total scan length Ltot is:
Ltot = first − last slice position + hrec + ∆L
(3.6)
∆L is calculated according to
If the scan range for a given type of examination is scanned
(entirely or in part) more than once, the dose length product for the entire examination DLPexam is derived by multiplying the DLP per scan series by the number of scan
series nSer:
DLPexam = DLP ⋅ nSer
(3.8)
In the context of this survey, nSer can be a non-integer
number if one of the scan series for an examination covers a portion only of the entire range or if multi-phase
examinations are performed on a fraction only of the patients.
3.4. Effective Dose
The ‘Effective Dose’ (E, unit: mSv) is calculated according to
k

DLPH/B
E =
⋅ fmean ⋅ kCT(H/B) ⋅ fage,region ⋅  CT, H 
PH/B
k
 CT, B 
x
(3.9)
where PH and PB are the so-called phantom factors, i.e. the
ratio between the weighted CTDI (derived from CTDI
measurements inside the standard dosimetry phantoms)
and the corresponding CTDI measured free-in-air, i.e.
without phantom, either for head (H) or body (B) scanning mode. fmean (unit: mSv/mGy·cm) is the average fac-
3. Dosimetry
tor for converting DLP (based on CTDI free-in-air) into
effective dose. fmean was calculated for the typical scan
ranges for standard CT examinations of adults (e.g. brain,
chest etc.) from a set of tabulated organ dose conversion
factors for male and female adults (Zankl et al. 1991).
The conversion factors used here apply to a specific scanner model (Somatom DRH) that was in common use at
the time when the GSF conversion factors were compiled.
kCT(H/B) is the scanner factor that allows these conversion
factors to be used also for other scanners, by matching the
characteristics of the particular scanner model to those of
the Somatom DRH. fage,region is a correction factor, dependent on the patient’s age and the scan region, derived from
the publication by Khursheed et al., that accounts for the
differences in patient size and organ location between adult
and paediatric patients. The term (kCT,H / kCT,/B)x is also required for scanner matching in order to account for the
smaller size of paediatric patients. The exponent x in this
term varies with age group between 1.5 (for newborn) and
0 (for age group 11 – 15 years); in head scanning mode, x
is equal to 0 for all age groups.
Following the same approach used for DLP, the effective
dose for the entire examination Eexam is derived from the
effective dose per scan series by multiplying by the number
of scan series nSer:
Eexam = E ⋅ nSer
(3.10)
The dose relevant data for the scanners involved in this
survey, the conversion factors and correction factors used
for the calculation of dose are tabulated in tables A1 to A3
in the appendix. With the exception of the CTDI measurements described above to obtain CTDI values for the
16 cm phantom in body scanning mode, no other dose
measurements were made. Instead, the normalised CTDI
values that form the basis for the CT-Expo software were
used. Dedicated comparisons, either with TLD measurements in an anthropomorphic phantom (Brix et al. 2004)
or with other programs for CT dose calculation (Tack and
Gevenois 2006), have led to the conclusion that the uncertainties and variances involved in our dosimetry are
always framed by other uncertainties in surveys of this
kind. Therefore dedicated dose measurements for the scanners at each institution participating in this survey would
not have significantly reduced the overall uncertainties.
7
8
3. Dosimetry
4. Results
4. Results
4.1. General Results
4.1.1 Phase I
In phase I, 663 out of 1640 addressees replied (40% participation rate) and reported in total 3.2 million CT examinations, including 20,900 paediatric CT examinations
on patients aged up to 10 years. As a projection from previous surveys (1999 and 2002), the total number of CT
scanners installed in Germany is presently about 2500,
and the annual total number of CT examinations is about
8.2 million (i.e., ca. 100 CT exams per 1000 inhabitants
per year). By making reference to these figures, the institutions that participated in phase I of the survey comprised
about 30% of all scanners and about 40% of all CT examinations.
The corrected number of paediatric CT examinations reported (including also the age group 11 to 15 years) was
about 30,700. Projected to all CT examinations in Germany, the contribution from paediatric CT examinations
amounts to 0.95%. Bearing in mind the uncertainties in
this projection, it can thus be concluded that the relative
proportion of paediatric CT examinations is in the order
of 1%.
4.1.2 Phase II
72 institutions with 102 CT scanners reporting at least 100
Private practices
4%
paediatric CT examinations per year in phase I were asked
to provide detailed protocol data for the paediatric CT
examinations carried out on their scanners. These institutions collectively included 21,600 (i.e. 70%) of the corrected annual number of paediatric CT examinations reported in phase I. In phase II, data were returned by 42
institutions (return rate 58%) operating 63 scanners (62%
of 102) and conducting 10,100 paediatric CT examinations (47% of 21600). The names of the institutions participating in this survey and the scanner models used by
them are listed in table A4 in the appendix.
Detailed protocol data were reported for a total of 54 scanners. Almost two thirds were provided by university hospitals and one third by general hospitals; only a few (4%)
were contributed by private practices. The majority of
paediatric CT examinations are therefore performed in
university hospitals (fig. 4.1). The vast majority of scanners were multi-slice in design, capable of acquiring simultaneously 2 or more slices per rotation. Most were either 2-slice to 6-slice scanners (35%) or 8-slice to 16-slice
scanners (39%); only 15% were single-slice scanners (fig.
4.2). The distribution by manufacturer (fig. 4.3) was very
similar to the patterns observed in previous surveys. About
one half of the scanners were less than 4 years old, whereas
about one third were between 4 and 7 years old; only 17%
were more than 7 years old (fig. 4.4). The vast majority of
N=20 to 64
11%
N=1
15%
General
hospitals
33%
University
hospitals
63%
Fig. 4.1 Distribution of participating institutions.
N=8 to16
39%
N=2 to 6
35%
Fig. 4.2 Distribution of technology of participating
scanners (N = number of simultaneously acquirable
slices).
9
10
4. Results
the scanners (91%) were equipped with a dose display
(fig. 4.5). Devices for automatic dose control were available on more than half of the scanners, but not used for all
types of examinations (fig. 4.6).
The annual number of paediatric CT examinations per
scanner varied from less than 100 to more than 600. About
one quarter of scanners each performed less than 100, from
100 to 149, 150 to 249 and more than 250 examinations,
respectively (fig. 4.7). On average, the institutions participating in phase II conducted 187 paediatric CT examinations per scanner and year. The fraction of paediatric
CT examinations varied between less than 1% and more
than 10% of all CT. The two largest groupings of institutions (about one third each) were for the ranges 1 to 2%
and 2 to 5% (fig. 4.8). Three of the participating institutions were dedicated children’s hospitals, where for each
more than 50% of all CT examinations were performed
on children aged up to 15 years. The average fraction of
Toshiba
7%
without dose display
9%
with dose display
91%
Fig. 4.5 Availability of dose displays.
GE
17%
always used
20%
Philips
(Elscint)
6%
Siemens
49%
paediatric CT examinations among the participating institutions was 2.5% of all CT.
never used
41%
Philips
17%
partially used
39%
Philips
(Picker)
4%
Fig. 4.3 Distribution of the manufacturers of the scanners participating in this survey.
Fig. 4.6 Frequency of use of automatic dose control
devices.
400 to 599 ≥600
4%
4%
> 7 years
17%
250 to 399
15%
<100
27%
< 4 years
50%
4 to 7 years
33%
Fig. 4.4 Age distribution of the participating scanners.
150 to 249
26%
100 to 149
24%
Fig. 4.7 Annual number of paediatric CT examinations
per scanner.
4. Results
The age distribution of paediatric CT examinations (fig.
4.9) was split almost equally into the age groups up to 5
>10%
7%
<1%
13%
5 to 10%
11%
years (40%), 6 to 10 years (28%) and 11 to 15 years (32%).
Only very few exams were performed on the newborn
(3%). Most of the examinations were standard brain scans
(52%), followed by scans of the chest (17%) and abdomen (incl. pelvis) (7%); spine and facial bone examinations were relatively rare. A larger fraction (17%) could
not be attributed to any of these 5 types of examination
(fig. 4.10a). A more detailed analysis (fig. 10b) shows that
these percentages also hold true for each age group, except for the newborn where chest and abdomen examinations are performed more frequently than in other age
groups.
1 to 2%
33%
2 to 5%
36%
Fig. 4.8 Fraction of paediatric CT examinations per participating scanner.
Newborn
3%
up to 1y
9%
Misc.
17%
11 to 15y
32%
Spine
3%
2 to 5y
28%
AbdoPel
7%
Brain
52%
Chest
17%
6 to 10y
28%
Facial bones/sinuses
4%
Relative fraction per age group
Fig. 4.9 Age distribution for paediatric CT examinations.
Fig. 4.10a Frequency distribution for types of paediatric
CT examination.
70%
60%
50%
BRN
FB/SIN
40%
CHE
30%
ABDPE
20%
LSP
10%
0%
newborn
up to 1y
2 to 5y
6 to 10y
Age group
11 to 15y
all
Fig. 4.10b
Relative fractions for
the types of examination per age group
(BRN = brain, FB/
SIN = facial bone/sinuses, CHE = chest,
ABDPE = abdomen
(incl. pelvis), LSP =
lumbar spine).
11
4. Results
4.2. Dosimetric Results
The dosimetric results are compiled in tables A5 to A9 in
the appendix. Table A5 shows the average values, sorted
with respect to age group. For the purposes of comparison, corresponding values are also shown from the two
preceding surveys in 1999 and 2002 that referred to adult
patients. For some age groups and types of examination,
the number of participating institutions and patients included was quite small. Therefore these data (given in Italics) should be treated with particular caution.
Table A6 presents the same data as in Table 5, but sorted
with respect to the type of examination. This allows a direct comparison of how the dose settings have been adapted
to patient’s age. In tables A7 and A8, corresponding data
are given for the first quartile and the median, respectively.
In table 9, third quartile values are presented that may serve
as a base for reference dose values. Comprehensive statistical data relating to each type of examination are compiled in tables A10 to A14.
4.3. Detailed Results
4.3.1 Manual settings vs. automatic dose control
As already mentioned above, devices for automatic dose
control were available on more than half of the scanners,
although not used for all types of examination. Accordingly, it is of interest to see whether there are significant
differences in the dose values between manual dose settings and those adjusted automatically.
In fig. 4.11, the fraction of users who employ automatic
dose control is analysed by type of examination. Whereas
about 50% of users employ ADC devices for examinations of the trunk region, only about 25% do so for examinations of the head region.
Differences in the dose values applied in ADC mode compared with those for manual setting, averaged over all age
groups, are shown in fig. 4.12. In general, higher doses
were applied in ADC mode than with manual settings.
Whereas only slight differences were found for examinations of the chest and the abdomen, significant differences
(25%) occur for examinations of the head region; for spine
examinations, doses applied in ADC mode are higher on
average by 70%.
4.3.2 Overranging effects
With the advent of scanners capable of acquiring an increasingly large number of slices simultaneously, overranging effects (i.e. the elongation of the scan range in
spiral scan mode to enable data interpolation at the beginning and at the end of the scan) make a significant contribution to the dose-length product. For most multi-slice
scanners, the elongation ∆L of the scan range amounts
roughly to 1.5 times the total beam width N·hcol (Nagel
2005). When compared with an examination of the same
body region performed in sequential scan mode, the increase in DLP resulting from this elongation also depends
on the scan length. It must therefore be expected that
overranging effects will become more pronounced with
the shorter scan ranges encountered in paediatric CT examinations.
increased CTDIvol with ADC vs. w/o ADC
70%
Fraction making use of ADC
12
60%
50%
40%
30%
20%
10%
0%
Brain
Sinuses
Chest
AbdoPel
Spine
Type of Exam
Fig. 4.11 Relative frequencies of use for devices for
automatic dose control (ADC).
80%
70%
60%
50%
40%
30%
20%
10%
0%
Brain
Sinuses
Chest
AbdoPel
Spine
Type of Exam
Fig. 4.12 Percentage increase in dose (CTDIvol) when
using ADC devices compared with manual dose setting
for the types of examination covered by this survey
(average for all age groups).
4. Results
As shown in fig. 4.13, all or most paediatric CT examinations are performed in spiral mode, with the exception of
brain examinations, where 90% of the protocols are set
up for sequential acquisition. Consequently, overranging
effects are negligible for brain examinations. For all other
types of examination investigated, overranging effects lead
100%
80%
on average to an increase in DLP in the order of 10 to
20% (fig. 4.14). Even greater increases were found for
spine examinations on newborn and infants owing to the
relatively short scan ranges. This additional exposure is
reduced with increasing age owing to the more extended
scan ranges found in these age groups (fig. 4.15). Under
special circumstances, i.e. on scanners with a large number
of simultaneously acquired slices (e.g. 64-slice scanners),
a significant increase in the DLP must be expected.
4.3.3 Age-specific dose adaptation
60%
40%
20%
0%
Brain
Sinuses
Chest
AbdoPel
Spine
Type of Exam
Fig. 4.13 Relative fractions of scan protocols performed
in spiral mode for the types of examination covered by
this survey (average for all age groups).
Relative Increase in DLP
40%
30%
Spine
Chest
Sinuses
AbdoPel
Brain
20%
10%
0%
Newborn
up to 1y
2 to 5y
6 to 10y
11 to 15y
Age Group
Fig. 4.14 Percentage increase in DLP due to overranging effects in spiral scanning mode for the types of
examination and age groups covered by this survey.
Since there is reduced x-ray beam attenuation for the
smaller size of paediatric patients relative to an adult, an
adequate image quality can be achieved with a lower dose.
Figs. 4.16a to 4.16e show how dose settings of CTDIvol
were adapted on average to the body weight of the patients. In the case of examinations in the trunk region,
CTDIvol32 is used for this analysis since, for a given scanner with tube potential kept constant, this quantity is proportional to the mAs setting. The conversion from patient’s
age to body weight as shown in fig. 4.17 is based on the
tabulated anatomical data from Prader et al. (1989). Adult
data (to which the relative dose level of 100% at 80 kg
body weight refers) were taken from the 2002 German
multi-slice CT survey (Brix et al. 2003).
In addition, values corresponding to recommendations for
examinations of the trunk region (Rogalla, 2004) and examinations of the head region (Morgan, 2003) have been
plotted for the purposes of comparison. Good agreement
is found between the average results of this survey and
the recommendations made by these authors for the three
most frequent types of examination (brain, chest and abdomen). For examinations of the facial bone/sinuses, dose
adaptation is more pronounced than recommended. For
spine examinations, dose settings are also reduced in comparison with adults, but without further adaptation to pa70
40
AbdoPel
Chest
Spine
Brain
Sinuses
30
20
10
Average Body Weight [kg]
Average Net Scan Length [cm]
50
60
50
40
30
20
10
0
0
Newborn up to 1y 2 to 5y
6 to 10y 11 to 15y Adults
Age Group
Fig. 4.15 Average net scan length for the types of
examination and age groups covered by this survey.
0
5
10
15
20
Patient’s Age [years]
Fig. 4.17 Correlation between patient’s age and
average body weight for male paediatric patients (from
Prader et al. 1989).
13
14
4. Results
tient’s weight; i.e. very similar settings are used for both
infants as well as 15 year-old adolescents.
Contrary to circumstances for brain examinations, examinations of the facial bone/sinuses are characterised by high
inherent contrast that allows reduced dose settings. Fig.
4.18a shows the ratio of the average settings of CTDIvol16
for these 2 types of examination, demonstrating that dose
settings for facial bone/sinuses examinations are lower by
a factor 3. For chest examinations, both the reduced attenuation and the increased inherent contrast are in fa4
Brain
3
100%
2
80%
Survey
Morgan
'Rogalla'
60%
40%
1
0
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age Group
20%
0%
0
20
40
60
80
100
Body weight (kg)
a.
Fig. 4.18a Ratio of the dose settings (CTDIvol) for examinations of the brain in comparison with those of the facial
bone/sinuses .
Facial Bone/Sinuses
Abdomen (incl. pelvis)
100%
100%
80%
80%
Survey
Morgan
'Rogalla'
60%
40%
40%
20%
20%
0%
Survey
Rogalla
60%
0%
0
20
40
60
80
100
0
Body weight (kg)
20
40
60
80
100
Body weight (kg)
b.
Chest
d.
Spine
100%
100%
80%
80%
Survey
Rogalla
60%
40%
40%
20%
20%
0%
Survey
Rogalla
60%
0%
0
20
40
60
Body weight (kg)
80
100
0
c.
20
40
60
Body weight (kg)
80
100
e.
Fig. 4.16 Adaptation of dose settings to patient’s body weight for the types of examination covered by this survey:
brain (a), facial bone/sinuses (b), chest (c), abdomen (incl. pelvis) (d), and lumbar spine (e). Relative dose values
(mean values) in terms of CTDIvol16 (a and b) and CTDIvol32 (c to e) refer (as 100%) to the corresponding mean values
from the German MSCT survey 2002 for adults (80 kg) (Brix et al. 2003). For the purposes of comparison, the corresponding relative values resulting from the recommendations of Morgan (2003) and Rogalla (2004) are also given.
4. Results
vour of reducing the dose compared with examinations of
the abdomen. As shown in fig. 4.18b, however, the
CTDIvol32 settings for chest examinations, when compared
with those for the abdomen, are lower by a factor of about
1.25 only.
CTDIvol AbdoPel vs. Chest
1.5
Chest
1.25
8
1
6
0.75
0.5
4
0.25
0
Newborn
<1y
2-5y
6-10y
11-15y
2
Adults
Age Group
Fig. 4.18b Ratio of the dose settings (CTDIvol) for examinations of the abdomen (incl. pelvis) in comparison with
those of the chest.
0
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
Brain
c.
Abdomen (incl. pelvis)
4
20
3
15
2
10
1
5
0
0
Newborn
<1y
2-5y
6-10y
11-15y
Age group
Adults
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
a.
Facial Bone/Sinuses
d.
Spine
1.0
15
10
0.5
5
0.0
0
Newborn
<1y
2-5y
6-10y
Age group
11-15y
Adults
b.
Newborn
<1y
2-5y
6-10y
Age group
11-15y
Adults
e.
Fig. 4.19 Mean values of effective dose in relation to patient age for types of CT examination brain (a), facial bone/
sinuses (b), chest (c), abdomen (incl. pelvis) (d) and lumbar spine (e). The corresponding mean values for adults were
taken from the German MSCT survey 2002 (Brix et al. 2003).
15
16
4. Results
Absolute values of effective dose per examination are
given (in mSv) in figs. 4.19 a to 4.19e, with analysis by
the patient’s age. Once again the corresponding results
for adults from the 2002 MSCT survey are also included
and these serve as the bases for the relative effective doses
Brain
400%
not corrected
risk corrected
300%
200%
100%
presented in figs. 4.20a to 4.20e. These relative values are
presented both with and without correction for the increased risk at lower patient age for the induction of malignant tumours, utilising age-dependent risk factors from
ICRP publication 60 (ICRP 1991). In comparison with
adults aged 50 years, the relative risk is 3 times higher for
the age group 10 to 19 years and 5 times higher for the
age group 0 to 9 years. Notwithstanding the fact that reduced dose settings are applied in a reasonable manner
for younger patients, the reduction in effective dose is less
pronounced, since, for the same exposure settings (i.e. kV
and mAs), the absorbed dose to the patient increases with
decreasing patient size. When the higher risk for tumour
induction is taken into account (risk corrected effective
dose), the relative doses are generally higher than for
adults. This holds true in particular for examinations of
the brain and the spine.
0%
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
a.
Facial Bone/Sinuses
Abdomen (incl. pelvis)
400%
250%
not corrected
risk corrected
not corrected
risk corrected
200%
300%
150%
200%
100%
100%
50%
0%
0%
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
b.
d.
Spine
Chest
400%
250%
not corrected
risk corrected
not corrected
risk corrected
200%
300%
150%
200%
100%
100%
50%
0%
0%
Newborn
<1y
2-5y
6-10y
Age group
11-15y
Adults
Newborn
c.
<1y
2-5y
6-10y
Age group
11-15y
Adults
e.
Fig. 4.20 Relative effective dose in relation to patient age for types of CT examination brain (a), facial bone/sinuses
(b), chest (c), abdomen (incl. pelvis) (d) and lumbar spine (e). Relative dose values refer (as 100%) to the corresponding mean values from the German MSCT survey 2002 for adults (80 kg) (Brix et al. 2003) and these are given both with
and without correction for differences in the risk for the induction of malignant tumours. The corresponding agedependent risk factors were taken from ICRP publication 60 (ICRP 1991).
4. Results
4.3.4 Use of reduced tube potential
100%
Chest
Sinuses
AbdoPel
Spine
Brain
80%
60%
40%
20%
0%
Newborn
up to 1y
2 to 5y
6 to 10y
11 to 15y
Age Group
Fig. 4.21 Percentage fraction of scan protocols applying
tube potentials below 110 kV, subdivided into the types of
examination and age groups covered by this survey.
The use of reduced tube potentials are frequently advocated, i.e. 80 kV or 100 kV instead of 120 kV, which is the
standard tube potential setting for adult CT examinations.
Accordingly, it is of interest to explore the extent to which
reduced kV settings are applied. In fig. 4.21, the fraction
of protocols utilising tube potentials below 110 kV are
presented, with analysis by patient age group. In general,
lower kV settings are applied to a greater extent for newborn and infants, and to a lesser extent for adolescents.
Reduced tube potentials are used more frequently for chest
examinations (35% on average), followed by facial bone/
sinuses (21%) and abdomen-pelvis (17%), whereas for
brain and spine examinations, standard kV settings (110
to 130 kV) are mostly used (more than 90% on average).
Brain
Brain - DLP16 per exam
200%
Survey
UK2003
100%
150%
80%
60%
100%
40%
50%
20%
0%
0%
0
20
40
60
80
Body weight (kg)
100
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
a.
Brain - CTDIvol16
c.
Brain - effective dose per exam
200%
200%
150%
150%
100%
100%
50%
50%
0%
0%
Newborn
<1y
2-5y
6-10y
Age group
11-15y
Adults
b.
Newborn
<1y
2-5y
6-10y
Age group
11-15y
Adults
d.
Fig. 4.22 Comparison of the results of this survey with those from the UK CT survey 2003 for brain examinations:
adaptation of the dose settings to the patient’s weight (a), CTDIvol16 (b), dose-length product (c) and effective dose
(d). The corresponding average German values for adults were taken from the German MSCT survey 2002.
17
18
4. Results
4.3.5 Comparison with other surveys
Up to now, there has been only one survey (the 2003 UK
CT survey, Shrimpton et al. 2005) in which data on the
dose settings used in paediatric CT examinations have been
collected, although this included fewer types of examination (brain and chest) and age groups (up to 1 year, 2 to 5
years and 6 to 10 years) compared with our survey. For
examinations of the brain, CTDIvol16 values and their age/
weight dependence are quite similar between surveys (figs.
4.22a and 4.22b); DLP and effective dose values found in
our survey, both expressed per exam, are somewhat higher
(figs. 4.22c and 4.22d). For examinations of the chest,
CTDIvol32 values are lower in our survey (fig. 4.23a), and
the dose adaptation to body weight is more pronounced
(fig. 4.23b); the same patterns hold true for DLP and effective dose per exam (figs. 4.23c and 4.23d). However, it
should be noted that overranging effects were not taken
into account for DLP and effective dose in the UK 2003
survey and that a different formalism was used for the
assessment of effective dose.
Chest
Chest - DLP32 per exam
200%
Survey
Rogalla
UK2003
100%
150%
80%
60%
100%
40%
50%
20%
0%
0%
0
20
40
60
80
Body weight(kg)
100
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
a.
Chest - CTDIvol32
c.
Chest - effective dose per exam
150%
250%
200%
100%
150%
100%
50%
50%
0%
0%
Newborn
<1y
2-5y
6-10y
Age group
11-15y
Adults
b.
Newborn
<1y
2-5y
6-10y
11-15y
Adults
Age group
Fig. 4.23 Comparison of the results of this survey with those from the UK CT survey 2003 for chest examinations:
adaptation of the dose settings to the patient’s weight (a), CTDIvol32 (b), dose-length product (c) and effective dose
(d). The corresponding average German values for adults were taken from the German MSCT survey 2002.
d.
5. Discussion
5. Discussion
As the first survey of its kind worldwide, the German survey on paediatric CT practice for 2005/2006 has revealed
a number of interesting details not previously known. Although the study is based on a limited number of institutions, with most (75%) being university sites, the results
of this survey can nevertheless be regarded as being nationally representative since the vast majority of paediatric CT examinations in Germany are carried out by these
particular institutions.
In contrast to practice in other countries, where children
up to 15 years account on average for 6% of all CT examinations (UNSCEAR 2000), the fraction of paediatric
CT examinations is relatively small in Germany (about
1%). In absolute terms, with about 100 annual CT exams
per 1000 inhabitants (Galanski et al. 2001), only 1 child
aged up to 15 years among 1000 inhabitants undergoes a
paediatric CT exam each year in Germany. In the U. S.,
with about 160 annual CT examinations per 1000 inhabitants and where the fraction of CT exams on paediatric
patients is 6.5% (CRCPD 2006), the corresponding figure is more than 10 times higher. This could be interpreted
that the justification for paediatric CT examinations is
viewed somewhat more restrictively in Germany.
Dose relevant data were collected for examinations of
brain, chest, abdomen (incl. pelvis), facial bone/sinuses
and spine, which were identified in the first part of this
survey as being the five most frequent types. Other types
of examination are quite rare and were therefore not taken
into account. Most paediatric CT examinations are restricted to the head region (roughly two thirds), whereas
only one third are carried out in the trunk region. In particular, the fraction of abdomen examinations, which is a
relatively frequent type of examination for adults (about
25%) and associated with a relatively high effective dose
(about 20 mSv), is quite rare in the paediatric domain (only
7%). Therefore, not only is the number of paediatric CT
examinations relatively small in Germany, but so is the
average dose per paediatric CT exam. The age distribution is relatively flat, i.e. similar frequencies are noted for
all age groups (up to 5 years, 6 to 10 years, and 11 to 15
years).
The majority of the scanners used for paediatric CT examinations are quite modern, i.e. spiral scanners with solid
state detectors. Most of these have multi-slice capabili-
ties, thus enabling significantly reduced total scan times.
Practically all of them (more than 90%) are equipped with
a dose display (indicating at least CTDIvol). Most of these
scanners (about 60%) are also equipped to a greater or
lesser extent with a sophisticated device for automatic dose
control (ADC), although only 20% of the users employ
ADC devices regularly, i.e. for all of their paediatric CT
protocols. Whereas ADC is used for about 50% of body
examinations, it is employed for only 25% of head exams.
Surprisingly, patient doses resulting from examinations
made with ADC are somewhat higher than from those with
manual adaptation of the dose settings. This can be explained in part by the present characteristics of some (but
not all) ADC devices, where exposure settings cannot be
made in terms of dose or mAs, but rather in terms of image quality, i.e. noise settings. In addition, these particular devices are designed to maintain the selected noise level
with changes in almost any exposure setting that has influence on the noise in the resulting image (ImPACT 2005).
Therefore, a reduced slice thickness or a sharper reconstruction filter inevitably forces these ADC devices to
operate at an increased dose level. However, since changes
in these parameters often have a positive effect on other
aspects of image quality, e.g. detail contrast, the corresponding increase in noise need be compensated for only
slightly or not at all.
In this context, the question arises how dose (or mAs)
should be adapted appropriately to the size of the patient.
In the past few years, a large number of papers have been
published on this subject with significantly differing recommendations: slight adaptation (e.g. Donelly et al. 2001),
intermediate adaptation (e.g. Rogalla 2004) and strong
adaptation (e.g. Huda et al. 2000). In fig. 5.1a, the characteristics of these recommendations are shown in terms of
relative dose settings as a function of body weight.
From theoretical considerations (i.e. from measurements
of the half value layer in body tissue, which amounts to
about 4 cm in the CT range), mAs should be adapted by a
factor of 2 for each 4 cm difference in tissue-equivalent
body diameter, in order to achieve images with a constant
noise level. However, in a fundamental study (Wilting et
al. 2001) in which the mAs settings were manually adapted
in this manner to patient size, it turned out that this method
19
5. Discussion
did not yield the results desired. Whereas the resulting
images exhibited almost the same noise independent of
the patient diameter (fig. 5.2a), CT images of patients of
smaller size were subjectively rated inferior by the radiologists (fig. 5.2b). This finding was interpreted as being
mainly due to the fact that slim patients have less body
fat, which serves as a kind of ’natural’ contrast agent.
Therefore, it is not sufficient to maintain a constant noise
level; instead, images of slim patients need to be less noisy
in order to maintain a constant contrast-to-noise ratio. As
a consequence, dose adaptation should be made in a more
gentle fashion, i.e. by a factor of 2 for each 8 cm difference in tissue-equivalent body diameter.
Using the data collected at a large German children’s hospital, showing the relationship between lateral body diameter and body weight (fig. 5.1b) (Schneider 2003), it
turns out that the moderate adaptation recommended by
Rogalla correlates almost perfectly with the ’factor 2 per
8 cm’ philosophy. In practice, this recommendation is quite
easy to apply, since it can be expressed fairly well by a
simple formula (‘Rogalla formula’):
rel. mAs =
body weight (in kg) + 5
85
(5.1)
This formula can be used, for example, to set up a limited
number of weight-adapted scan protocols (e.g. 0 – 5 kg, 6
– 10 kg, 11 – 20 kg, 21 – 40 kg, 41 – 60 kg, 61 – 80 kg),
utilising the (optimised) dose settings for an average male
adult of about 80 kg body weight as a starting point. These
protocols can then be applied simply on the basis of the
patient’s body weight. An almost identical relationship has
been recommended by another paediatric CT research
group from Aachen University (Honnef et al. 2004).
The most surprising result of this survey is the way in
which dose is adapted to body weight: on average this is
in quite good agreement with the Rogalla formula for chest
and abdomen examinations (see figs. 4.16c and 4.16d).
The same should also hold true for spine examinations,
but with dose settings somewhat reduced, although in practice almost the same dose (CTDIvol) is applied regardless
of patient’s age (fig. 4.16e). This might be due to the circumstances of spine examinations being quite rare, so presumably less attention has yet been paid to optimising these
protocols.
In paediatric CT examinations of the head region, it would
not make much sense to adapt the dose settings according
to body weight, since the size of the head is disproportionately large for infants and children. Consequently, dose
adaptation should best be made according to patient’s age.
As an additional surprise, the age adaptation found in this
survey for CT examinations of the brain (fig. 4.16a) almost perfectly matches another recommendation that has
been developed in the Philips CT community (Morgan
2003). Fig. 4.16a also reveals that even the ‘gentle’ dose
adaptation given by the Rogalla formula would reduce the
dose by an overly large extent. The dose adaptation found
for CT examinations of the facial bone/sinuses, however,
is more of the Rogalla formula type (fig. 4.16b), although
a pattern similar to that for brain examinations should be
expected. This might be explained by the circumstances
that these examinations are also relatively rare and that even for adults - there is still little agreement on the appropriate dose settings for this type of examination.
At present, ADC devices implemented in MSCT scanners
from Philips and Siemens offer a more ‘gentle’ mAs adaptation (i.e. roughly by a factor of 2 per 8 cm), thus providing an ‘adequate’ noise compensation, whereas ADC
40
Donelly
Rogalla
Huda
Patients
Fit
35
Lateral diameter (cm)
100%
Relative mAs
20
75%
50%
25%
30
25
20
15
10
5
0
0%
0
20
40
60
Body weight (kg)
80
100
a.
0
20
40
60
Body weight (kg)
80
100
b.
Fig. 5.1 The characteristics of three representative recommendations on how to adapt the dose settings to the patient’s
body weight (a) and the correlation between lateral diameter and body weight (b), based on patient data from a major
German children’s hospital (Schneider 2003). The bright lines inside the diagrams indicate that the ’factor 2 per 8 cm
philosophy’ is almost perfectly met by the moderate dose adaptation recommended by Rogalla (2004).
5. Discussion
devices found in GE and Toshiba MSCT scanners attempt
to ensure a constant noise level by using a strong mAs
adaptation that follows theoretical considerations (i.e. by
a factor of 2 per 4 cm).
In this context, it should be kept in mind that ADC devices do not reduce dose per se, but merely accomplish
dose adaptation according to the size of the patient, i.e.
they simply have an impact on the relative dose settings.
Absolute dose settings, however, are still dependent on
the user’s preferences. These can either be made in terms
of mAs for a ‘standard’ patient (‘reference mAs control’,
as provided by Philips and Siemens) or in terms of image
noise (‘standard deviation based control’, as provided by
GE and Toshiba). Whereas a number of commonly agreed
recommendations on dose have been developed in the past
few years (e.g. diagnostic reference levels) and these can
be translated without too much effort into mAs settings,
things are much more complex for noise-based ADC devices. This is due to the fact that no agreement exists on
adequate noise levels and also that contrast-to-noise ratio,
rather image noise, is the more relevant descriptor of image quality that needs to be maintained. This becomes
apparent on changes in slice thickness and patient size,
whereby detail contrast is also altered. The results from
this survey and the publications mentioned above that are
in favour of a more gentle dose adaptation should be seen
as suggestions to the relevant manufacturers to reflect on
their present ADC philosophy (for both regulation mechanism and control).
Although the results of this survey revealed that dose settings concerning local dose (i.e. CTDIvol) were reasonably
well adapted to the age or the body weight of the patients,
it must be noted that effective doses for complete examinations were only slightly reduced when compared with
adults (fig. 4.20 a to e). When also taking into account the
increased sensitivity of paediatric patients for the induc-
a.
tion of malignant tumours, the risk-corrected effective dose
is not reduced, but made even greater. Therefore the use
of adequately adapted mAs settings is obligatory so as to
improve the situation, although it is by no means a complete solution and the necessity still exists to justify carefully each paediatric CT examinations.
As far as absolute dose settings are concerned, examinations of the facial bone/sinuses are fully adjusted for the
improved inherent contrast, with dose reductions by a factor of about 3 compared with brain examinations. For examinations of the chest, however, dose is only slightly
reduced compared with abdominal examinations (by about
a factor of 1.25). In this case, a larger reduction of between 1.5 and 2, as recommended by e.g. Rogalla (2004)
and Honnef et al. (2004), can be justified owing to the
reduced attenuation and the improved inherent contrast in
the chest region.
All of the scanners involved in this survey were spiral
scanners, and almost all examinations were made in helical scan mode, with the exception of brain examinations
that were preferentially (about 90%) conducted in sequential scan mode. Users of single-slice scanners regularly
conducted their helical examinations with increased pitch
settings (1.5 and higher). However, for the majority of
multi-slice scanners, i.e. those making use of the so-called
‘effective mAs concept’ (MSCT scanners made by Elscint,
Philips and Siemens), dose no longer depends on pitch
setting and so the selected pitch factor is not relevant in
this context. For scanners not employing effective mAs
(MSCT scanners from GE and Toshiba), increased pitch
settings result in reduced dose, but at the expense of an
increased noise if mAs settings are not adjusted manually.
As expected, overranging effects are most pronounced for
examinations that comprise a short scan range only (i.e.
spine and facial bone/sinuses), and for newborn and in-
b.
Fig. 5.2 Measured image noise (a) and subjective assessment of noise, visibility of small structures and diagnostic
confidence (b) for scan protocols with mAs settings manually adapted to the lateral patient diameter (by a factor 2 per
4 cm difference). Whereas the objective image noise was almost constant for different patient diameters between 24
and 36 cm, the subjective rating of image quality became increasingly worse with decreasing patient diameter (from:
Wilting et al. 2001).
21
22
5. Discussion
fant patients in particular. Although the average increases
in dose-length product do not appear dramatic when compared with examinations made in sequential scan mode, it
should be kept in mind that overranging effects can be
quite large for true 64-slice scanners (e.g. about 60% in
the case of spine examinations). Therefore it is worthwhile
considering either to conduct these examinations in sequential scan mode or to operate 64-slice scanners in 16slice mode with reduced beam width.
In contrast to CTDIvol, integral dose quantities such as effective dose are subject to two additional factors (scan
length and number of scan series (i.e. phases)), which are
heavily dependent on the user’s preferences. Whereas
multi-phase examinations are very rare in paediatric CT
(see tab. A5), the average scan length was often somewhat larger than expected (and in some cases even larger
than for adults). There is therefore some room for improvement by more careful adjustment of the length of the scan
range.
Only a minority of the users applied reduced settings of
tube potential (i.e. kV). Contrary to mAs, changes in kV
setting alter not only the quantity, but also the quality of
the radiation. There is a clear benefit from low kV settings in CT angiography, since the gain in contrast out-
weighs by far the increase in noise. However for non-enhanced scans or non-vascular examinations with administration of contrast agents, image contrast in areas of tissue free from contrast agent will remain almost constant.
In practice, noise is not compensated for by improved
contrast in these cases and, in addition, the softer beam is
absorbed more strongly by the patient. As a result, the
relationship between dose and image quality is not in favour of reduced tube potentials for non-CTA examinations.
Recommendations for low kV settings are merely a relic
of the past when mAs settings could not be reduced much
and a reduction in kV was the only solution. Modern scanners, however, allow the tube current-time product to be
reduced down to values of about 10 mAs, which corresponds to a CTDIvol32 of between 0.5 and 1 mGy (dependent on the type of scanner). There is therefore rarely a
need to use kV settings other than 120 kV (except for CTA).
There are only limited possibilities for comparison with
the results from other surveys. Whereas dose values for
brain examinations are similar to those in the UK survey,
dose values reported for chest examinations in the UK are
higher, and the dose adaptation to body weight is less pronounced. Therefore it seems that efforts towards dose
optimisation in paediatric CT are more advanced in Germany.
6. Reference Values, Feedback Action
6. Reference Values, Feedback Action
6.1. Proposal for Diagnostic Reference Values
Proposals for diagnostic reference values for volume CTDI
(CTDI vol) and dose-length product per examination
(DLPexam) are compiled in table A15 in the appendix for
the age groups and types of examination covered by this
survey. All values are based on the 3rd quartile results from
this survey.
For a number of reasons, however, 3rd quartile values were
not used directly, but in a modified manner:
• For some types of examination and age groups (facial
bone/sinuses and lumbar spine for newborn and infants), the sample size was very small and was thus
associated with relatively large uncertainties.
• Dose values for chest examinations differed only
slightly from those for abdomen examinations, i.e. they
were unnecessarily high.
• Most users did not differentiate in their dose settings
between newborn and infants.
Modifications were made as follows:
• The 3rd quartile value of CTDIvol for abdomen examinations (incl. pelvis) from the 2002 MSCT survey and
the present reference value of 60 mGy for brain examinations were taken as starting points.
• For all other types of examination, the corresponding
CTDIvol values for adults were derived as follows: 1/3
of the brain value for facial bone/sinuses; 2/3 of the
abdomen value for chest; and 2.5 times the abdomen
value for lumbar spine.
• The adaptation of CTDIvol values to the patient’s age
was made according to the recommendations of Morgan
(head region) and Rogalla (trunk region), since both
approaches already showed good correlation with the
results of this survey.
• The DLP per exam values were derived by multiplying the CTDIvol values by each of the corresponding
average values for net scan length, overranging and
number of scan series.
In general, the proposals that were modified in this way
are in good agreement with the 3rd quartile values from
this survey. Larger discrepancies are found only in those
cases where modifications were necessary for the reasons
mentioned above. The values compiled in table A15 are
graduated in a meaningful (moderate adaptation to patient’s
age and weight) and consistent manner, i.e. the correlation between the different types of examination is in accordance with the results from other surveys and relevant
publications.
6.2. Comparison with other Reference Values
The first proposal for reference values with respect to paediatric CT examinations were published in 2000 by
Shrimpton et al. (2000), based on a European-wide survey with 40 participating institutions. Cross-validation can
be made for three age-groups (up to 1 year, 2 to 5 years, 6
to 10 years) and three types of examination (brain, chest
and abdomen (incl. pelvis)). The values published by
Shrimpton et al. were given in terms of CTDIw16 and DLP16
per exam. For the purposes of comparison, these CTDIw16
values were converted into CTDIvol16 on the assumption
of a pitch of 1 for brain and a pitch of 1.5 for the other
types of examination, since these latter were performed
predominantly in spiral scanning mode.
The results of comparing the data of Shrimpton et al.
(2000) with our proposals are given in table A16 in the
appendix (see column ‘ratio’). For brain examinations,
both values are almost identical, with our proposals being
somewhat lower, except for the age group ‘up to 1 year’
where our proposed DLP is somewhat higher. This is due
to the inclusion of a scan length of 7.5 cm in the Shrimpton
et al. data, which appears relatively small. For chest and
abdomen examinations, all our proposals are significantly
lower (by a factor of between 1.5 and 4, depending on the
age group and dose quantity).
Bearing in mind that our proposals are based on a moderate adaptation of dose settings to patient’s age or weight
and that chest values were only slightly modified with
respect to abdomen values, the values proposed by Shrimp-
23
24
6. Reference Values, Feedback Action
ton et al. are much too high from our point of view. A
possible explanation might be that the underlying survey
was conducted before the majority of CT users became
aware of the need for appropriately adapted dose settings
for paediatric purposes. For want of other values, the proposals of Shrimpton et al. were used in the present ver-
sion of the CT guidelines (Nagel and Vogel 2004) for general orientation purposes. With the proposals in table A15,
however, more appropriate values are now available, which
make use of the potential for dose reduction in the paediatric range. A revision of the CT guidelines is in preparation.
6.3. Feedback Action
As with the two preceding surveys conducted by us, feedback was given to all participants in this survey. This was
done in terms of absolute and relative dose values, the
latter referring to the proposed reference values for the
corresponding age group, type of examination, and dose
quantity.
For this purpose, the dose values that were calculated for
the particular scanner model from the reported exposure
settings were presented as shown in figs. A4 to A6 in the
appendix. In sheet 1 (fig. A4), the reported scan protocol
settings are listed along with the resulting dose values.
Local dose quantities, such as CTDIw and CTDIvol, depend exclusively on the tube potential (U), the tube load
(Q), the beam width (N·hcol) and the pitch, and they apply
per scan series. Integral dose quantities, such as doselength product (DLP) and effective dose (E), depend additionally on the scan length (L) and the number of scan
series (nSer.), and they refer to the entire examination. Effective dose enables comparisons with other examination
techniques using ionising radiation and with natural background radiation (e.g. 2.1 mSv per year in Germany). The
category ‘relative values’ provides percentage values for
each dose quantity and type of examination, indicating
the dose level for each participant in relation to the proposed reference value.
In sheet 2 (fig. A5), these same facts are presented in
graphical form for CTDIvol and DLPexam. Relative dose values above 100% indicate that the particular participant
should consider corrective actions, dependent on whether
this breach relates to the local dose (CTDIvol ), the integral
radiation exposure (DLPexam) or both. In the case of the
first dose quantity, the mAs setting should be reduced accordingly; in the latter case, a multitude of factors should
be taken into account. Sheet 3 (figs. A6a to A6d) therefore provides information that allows detailed analysis of
the potential sources (act. = actual values of the particular
participant; ref. = average values for this survey). Apart
from the local dose, excessive values of DLPexam can be
caused by an above-average scan length L, a below-average pitch factor p, an above-average number of scan series or an unfavourable combination of all these factors.
Since thin slices are associated with increased image noise
and this may therefore tempt the user to increase mAs
settings, a comparison of the slice thickness reveals if this
aspect could be of importance.
Finally, explanations on how to interpret the results and
how to make use of them were provided on a separate
sheet.
7. Recommendations
7. Recommendations
In order to ensure that paediatric CT examinations are
carried out in a dose-optimised fashion, the following recommendations should be observed:
A. Choice of equipment
If possible, paediatric CT examinations should be performed on modern, dose-efficient scanners (i.e. spiral scanners with solid-state detectors) only. Multi-slice (MSCT)
scanners are advantageous insofar as these allow much
shorter scan times compared with single-slice scanners.
B. Choice of tube potential
Tube voltage settings below 110 kV should be used only
if the range of mAs settings is not sufficient to achieve the
reduced dose settings desired (e.g. chest examinations on
newborn and infants). Otherwise, the standard voltage
setting for the particular scanner (between 110 and 130
kV) should be applied.
C. Beam collimation on MSCT scanners
For paediatric examinations and their associated short scan
ranges, a beam width (total collimation) of between 10
and 24 mm is optimal. Narrower beam widths should be
avoided, since the patient’s exposure will increase excessively due to overbeaming effects (i.e. the portion of the
beam not used for imaging). In spiral scanning mode, a
wider beam width should also be avoided since overranging effects (i.e. the consequence of extra rotations)
will inevitably become more pronounced.
Relative mAs setting
Age group
D. Pitch factor
For single-slice scanners, spiral scans should be made with
an increased pitch of 1.5, resulting in a corresponding dose
reduction. However, for multi-slice scanners that achieve
their mAs settings in terms of ‘effective mAs’ or ’mAs
per slice’ (i.e. MSCT scanners from Elscint, Philips and
Siemens), dose is no longer affected by the pitch setting,
since any modification in the pitch factor is associated
with a corresponding adjustment of the electrical mAs
product. For these particular scanners, the pitch factor is
modified for other reasons (scan speed, reduction of artefacts). In contrast, multi-slice scanners from GE and
Toshiba achieve their mAs settings in terms of ‘electrical
mAs’ (similar to single-slice scanners); therefore increased
pitch settings will reduce the patient’s dose, but at the expense of an increased image noise. Particular attention
should be paid if pitch settings below 1 are used for these
types of scanner, since the overlapping scans will result in
increased dose unless the electrical mAs settings are manually adapted (i.e. reduced). A look at the scanner’s dose
display (increasing CTDIvol values at pitch settings < 1)
reveals whether this aspect is of importance.
E. Dose adaptation
The adaptation of dose settings according to age or body
weight should be made in a moderate fashion (factor ±2
for each 8 cm difference in effective body diameter for
examinations of the trunk region). The data given in tabs.
7.1 and 7.2 can be used to create sets of age- or weightadapted scan protocols.
Body weight
Age (appr.)
Relative mAs setting
Abdomen
(w. pelvis)
Chest
Spine
10%
7%
25%
Brain
Facial
bone/sinuses
Newborn
45%
15%
0-5
0-3m
<1y
55%
18%
6 - 10
4m-1y
17%
10%
50%
2-5y
65%
22%
11 - 20
2-5y
30%
20%
75%
6 - 10 y
85%
28%
21 - 40
6 - 12 y
50%
33%
125%
11 - 15 y
100%
33%
41 - 60
13 - 18 y
75%
50%
200%
> 15 y
100%
33%
61 - 80
>18 y
100%
65%
250%
Tab. 7.1 Age-adapted relative mAs values for paediatric
CT examinations of the head region. Starting point
(=100%) is the optimised mAs setting for brain examinations on adults, which corresponds to a CTDIvol16 of not
more that 60 mGy.
(kg)
Tab. 7.2 Weight-adapted relative mAs values for paediatric CT examinations of the trunk region. Starting point
(=100%) is the optimised mAs setting for abdomen examinations on adults, which corresponds to a CTDIvol32 of
not more that 15 mGy.
25
26
7. Recommendations
F. Automatic dose control
G. Dose display
Automatic dose control should be used only if these devices are designed to provide a moderate dose adaptation.
The default dose setting (‘reference mAs’) for the particular type of examination should be below the reference
value for adults given in tab. A15. Purely noise-based ADC
devices are difficult to handle owing to both their regulation characteristic (mAs factor ±2 per 4 cm difference in
effective diameter) and their settings (pre-selection of image quality instead of dose). Therefore manual dose adaptation as described above should be preferred.
Up to now all scanners display the CTDIvol that relates to
the larger body phantom (CTDIvol32) if the scan is made in
body scanning mode, regardless of the body size. As a
consequence, reference values based on CTDIvol32 must be
used for optimisation purposes. The CTDIvol16 values that
are additionally given in tab. A15 for the age groups up to
10 years are only informative at present (e.g. for the assessment of realistic organ doses). This might change in
the future, however, if the dose display is made to refer
primarily to the diameter of the scanned body region and
not to the scan mode.
References
References
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Brenner DJ, Elliston CD, Hall EJ, Berdon WE (2001)
Estimated risks of radiation-induced fatal cancer from
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Morgan H (2003) Image quality improvement and dose
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4
LightSpeed VFX 16
1
6
CT Aura
Brilliance 6
Mx8000 IDT, Brilliance 16
Brilliance 40/64
PQ Series (Filter 0)
Somatom Plus 4 Series
Balance, Emotion (pre '00)
Balance, Emotion (post '00)
Volume Zoom
Philips
Philips
Philips
Philips
Picker
Siemens
Siemens
Siemens
Siemens
16
16
Sensation 64
Aquilion 4
Aquilion 16
1
Siemens
Toshiba
Toshiba
Remarks
32
16
2
120
20
32
20
24
24
18
20
20
10
10
10
10
40
24
24
10
40
20
20
1
2
3
3
16
3
OR
2.00
1
2.07
4.00
1.55
1.01
1.01
0.31
0.31
2.00
2.00
1.50
0.54
0.57
0.58
2.00
0.47
0.38
0.38
0.53
0.73
m
1
1
2
2.5
1.7
1.7
0.3
0.3
1
0
7
3
1.5
1.4
3
3
3
3
0.8
(mm)
dz
OR
0.05
-0.70
-0.16
1.01
1.01
1.11
1.11
-1.00
-1.00
-1.00
-1.00
1.18
1.02
0.95
-1.00
0.74
1.02
1.02
0.90
0.23
b
for overbeaming correction purposes only
120
120
120
120
120
120
120
130
130
120
130
120
120
120
120
120
120
120
20
(mm)
(kV)
120
(N·h)ref
Uref
Miscellaneous
0.220
0.207
0.134
0.184
0.177
0.190
0.200
0.241
0.270
0,146
0.168
0.110
0.130
0.130
0.250
0.201
0.182
0.182
0.182
0.105
(mGy/mAs)
n CTDIw,H
H
0.77
0.67
0.74
0.76
0.75
0.76
0.76
0.73
0.76
0.82
0.44
0.75
0.75
0.75
0.57
0.64
0.64
0.64
0.64
0.59
P
Head
CT
0.90
0.80
0.90
0.90
0.90
0.90
0.90
0.90
0.90
1.00
0.60
0.90
0.90
0.90
0.70
0.80
0.80
0.80
0.80
0.70
k
0.121
0.111
0.065
0.076
0.074
0.077
0.083
0.126
0.150
0.083
0.112
0.057
0.067
0.067
0.120
0.097
0.094
0.094
0.094
0.043
(mGy/mAs)
CTDIw,B32
n
0.33
0.29
0.36
0.45
0.44
0.44
0.49
0.38
0.42
0.47
0.29
0.39
0.39
0.39
0.28
0.39
0.39
0.39
0.39
0.24
PB32
Body
0,65
0,65
0,80
1,00
1,00
1,00
1,00
0,80
0,80
1,00
0,50
0,80
0,80
0,80
0,50
0,80
0,80
0,80
0,80
0,50
kCT
0.220
0.207
0.134
0.131
0.127
0.132
0.143
0.241
0.270
0.146
0.168
0.110
0.130
0.130
0.250
0.201
0.188
0.188
0.188
0.105
(mGy/mAs)
n CTDIw,B16
0.77
0.67
0.74
0.77
0.76
0.76
0.84
0.73
0.76
0.82
0.44
0.75
0.75
0.75
0.57
0.64
0.78
0.78
0.78
0.59
B16
P
Body (paed.)
CT
0.90
0.80
0.90
0.90
0.90
0.90
1.00
0.90
0.90
1.00
0.60
0.90
0.90
0.90
0.70
0.80
0.90
0.90
0.90
0.70
k
Tab. A1 Dose-relevant data for the scanners participating in this survey (N = number of slices acquired simultaneously and independently per rotation; Uref
and (N·h)ref = reference tube potential and beam width, resp., to which all other data refer; dz = overbeaming parameter; mOR and bOR = overranging
parameters;nCTDIw,H = normalized weighted CTDI for head scanning mode; nCTDIw,B32 = normalized weighted CTDI for body scanning mode, referring to
the 32cm body phantom; nCTDIw,B16 = normalized weighted CTDI for body scanning mode, referring to the 16cm head phantom; PH, PB32 and PB16 = phantom
factors for conversion from weighted CTDI to CTDI free-in-air; kCT = scanner factor)
for 1 mm slice collimation only
4
Sensation 16
Siemens
4
10
Sensation 4
Sensation 10
Siemens
Siemens
4
1
1
1
1
40/64
16
64
LightSpeed 16, -Pro
LightSpeed VCT
GE
GE
16
LightSpeed QX/i,-Plus
GE
GE
N
2
Scanner
CT Twin
Elscint
Manufacturer
I
Appendix
II
Standard examination
Name
Anatomical landmarks
Abbr.
cranial
Scan range
caudal
(male)
(female)
from-to
from-to
Length
f mean
(cm)
(mSv/mGy*cm)
(m.)
(f.)
(m.)
(f.)
Routine Brain
BRN
Vertex
Skull base
94
82
89
77
12
12
0.0022
0.0024
Facial Bones /
Sinuses
FB/SIN
Superior margin
of frontal sinus
Occlusial plane
89
78
85
74
11
11
0.0022
0.0024
Routine Chest
CHE
C7 / T1
Sinus
69
41
65
39
28
26
0.0068
0.0088
Routine Abdomen
(tot.)
ABDPE
Diaphragm
Pubic symphysis
43
0
41
0
43
41
0.0072
0.0104
Lumbar Spine
LSP
L2/3
L3/4
35
29
33
27
6
6
0.0096
0.0108
Tab. A2 Standard CT examinations and their corresponding anatomical landmarks, scan ranges, and mean conversion factors, based on the mathematical phantoms ‚ADAM’ and ‚EVA’ (Zankl et al. 1991)
fage, region
Age group
x
Head and
neck
Chest
Abdomen
and pelvis
Newborn
3.53
3.90
4.47
1.5
up to 1 year
2.63
2.70
2.94
1.0
2 to 5 years
1.51
2.03
2.12
1.0
6 to 10 years
1.25
1.53
1.55
0.5
11 to 15 years
1.05
1.11
1.10
0
Tab. A3 Correction factors to convert from effective dose values for adults
to those for particular age groups and body regions. The factors were taken
from the publication by Khursheed et al. (2002) and adapted to the formalism for effective dose assessment used in this survey.
III
City
Institution
Department
Scanner
Manufact.
Type
Slices
Aachen
University
Radiology
Siemens
Sensation 16
Aachen
University
Neuro Radiology
Siemens
Volume Zoom
16
4
Baden-Baden
Hospital
Radiology
Siemens
Emotion
1
Bonn
University
Radiology
Siemens
Plus 4
1
Bonn
University
Radiology
Philips
Mx8000 IDT
16
Bonn
University
Neuro Radiology
Philips
Brilliance 16
16
Dresden
Düsseldorf
University
University
Radiology
Radiology
Siemens
Siemens
Sensation 16
Sensation 64
16
32
Düsseldorf
University
Neuroradiologie
Siemens
Volume Zoom
4
Erfurt
Hospital
Radiology
GE
LightSpeed 16
16
Erfurt
Erlangen
Hospital
University
Radiology
Radiology
GE
Siemens
LightSpeed QX/i
Sensation 10
4
10
Frankfurt
University
Neuro Radiology
Philips
Brilliance 6
6
Frankfurt
University
Radiology
Siemens
Sensation 16
16
Freiburg
Fulda
University
Hospital
Neuroradiologie
Radiology
Siemens
GE
Sensation 16
LightSpeed Plus
16
4
Fulda
Hospital
Radiology
GE
LightSpeed 16 Pro
16
Giessen
University
Paed. Radiology
Siemens
Balance
1
Greifswald
Gummersbach
University
Hospital
Radiology
Radiology
Siemens
Siemens
Sensation 16
Sensation 4
16
4
Halle
University
Radiology
Siemens
Volume Zoom
4
Halle
University
Radiology
Siemens
Sensation 64
32
Hamburg-Heidberg
Hannover
Hospital
University
Radiology
Neuro Radiology
Philips
GE
Mx8000 IDT
LightSpeed VFX16
16
16
Hannover
University
Radiology
GE
LightSpeed VCT
64
Hannover
Childrens hosp.
Paed. Radiology
Philips
Brilliance 6
6
Heidelberg
Heidelberg
University
University
Radiology
Radiology
Siemens
Siemens
Volume Zoom
Sensation 16
4
16
Jena
University
Radiology
GE
LightSpeed 16
16
Jena
University
Radiology
GE
LightSpeed QX/i
4
Kassel
Leipzig
Hospital
University
Radiology
Radiology
Elscint
Siemens
CT Twin
Volume Zoom
2
4
Leipzig
University
Radiology
Philips
Mx8000 IDT
16
Lübeck
University
Radiology
Toshiba
Aquilion 4
4
Lübeck
Magdeburg
University
University
Radiology
Radiology
Toshiba
Toshiba
Aquilion 16
Aquilion 16
16
16
1
Mainz
University
Neuro Radiology
Picker
PQ5000
Mainz
University
Radiology
Siemens
Volume Zoom
4
Mainz
Marburg
University
University
Radiology
Radiology
Philips
Siemens
Brilliance 64
Volume Zoom
64
4
Mönchengladbach
Hospital
Radiology
Siemens
Emotion
1
München
Heart centre
Radiology
Siemens
Sensation 64
32
München
München-Schwabing
University
Hospital
Paed. Radiology
Radiology
Philips
Siemens
Aura
Sensation 16
1
16
München-Schwabing
Hospital
Radiology
Siemens
Sensation 16
16
Münster
Hospital
Radiology
Toshiba
Aquilion 64
64
Neubrandenburg
Oldenburg
Hospital
Hospital
Radiology
Radiology
Philips
Siemens
Brilliance 10
Plus 4
10
1
Stuttgart
Hospital
Radiology
Picker
PQ5000
1
Stuttgart
Hospital
Radiology
GE
LightSpeed Plus
4
Trier
Hospital
Radiology
Siemens
Plus 4
4
Ulm
Wiesbaden
University
Private practice
Radiology
Radiology
Elscint
Elscint
CT Twin
CT Twin
2
2
Würzburg
University
Radiology
Siemens
Sensation 16
16
Tab. A4 Institutions providing examination protocols for phase II of the survey and their scanner models.
Age group
Newborn
up to 1 year
2 to 5 years
6 to 10 years
11 to 15 years
Adults
(MSCT survey
2002)
Qel
116
108
100
108
118
115
110
108
114
116
119
113
111
116
118
121
114
114
115
119
122
118
119
119
121
122
123
128
121
130
127
126
127
124
131
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
381
228
191
239
327
285
200
163
123
317
149
125
90
86
284
167
87
69
78
231
133
61
55
68
197
118
53
52
46
162
61
45
44
81
128
[kV] [mAs]
U
Brain
Type of examination
2.4
1.5
1.4
1.9
2.2
1.2
0.7
0.7
0.9
1.4
0.9
0.7
0.7
0.8
1.3
1.0
0.7
0.7
0.8
1.3
1.1
0.7
0.7
0.8
1.2
0.9
0.6
0.7
0.8
1.2
0.8
0.6
0.6
0.9
1.2
[s]
tR
1.0
1.0
1.0
1.0
1.0
3.1
3.3
3.4
3.2
2.8
11.8
12.9
13.7
10.0
8.7
8.5
11.0
13.2
10.3
7.0
9.9
11.6
14.6
9.4
9.3
11.7
14.5
13.0
11.3
6.7
12.3
8.6
10.8
11.4
6.3
N
3.3
8.9
8.4
3.3
8.4
2.3
4.3
4.0
1.7
5.7
1.4
2.7
2.6
1.3
3.5
1.5
2.6
2.5
1.2
3.9
1.6
2.5
2.1
1.2
3.4
1.4
2.0
1.9
1.1
3.5
1.5
2.3
2.0
1.2
3.3
[mm]
1.1
1.3
1.3
1.3
1.0
1.0
1.3
1.4
1.1
1.0
1.0
1.2
1.2
1.2
1.0
1.1
1.2
1.2
1.2
1.0
1.2
1.2
1.2
1.1
1.0
1.1
1.2
1.2
1.2
1.0
1.3
1.2
1.3
1.4
1.0
3.3
8.9
8.4
3.3
8.4
2.8
6.6
6.3
2.4
7.3
1.8
4.5
4.4
2.0
5.7
2.2
4.4
4.2
2.1
5.9
2.0
4.1
3.7
2.1
5.7
2.1
3.7
3.4
2.2
5.4
2.5
3.8
3.3
2.4
4.5
[mm]
hcol Pitch hrec
W
85
357
746
85
349
812
117
339
747
88
340
740
139
342
741
386 1638
46
-100
423 1995
37
482 1804
43
-103
424 2042
37
437 1740
46
-102
428 2023
46
434 1563
43
-127
523 2273
36
575 2000
50
-88
399 1850
36
C
Window
Examination parameters
6.0
40.7
29.8
9.1
12.3
13.5
41.9
31.0
10.2
13.2
15.9
35.9
26.0
11.4
13.9
11.7
29.0
20.4
9.8
12.8
11.1
25.1
16.4
9.1
11.9
9.7
19.6
12.3
7.3
10.7
8.3
14.2
10.1
8.3
9.8
[cm]
1.0
1.6
1.2
1.1
1.5
1.0
1.5
1.0
1.0
1.3
1.0
1.2
1.0
1.0
1.1
1.0
1.2
1.0
1.0
1.0
1.0
1.1
1.0
1.0
1.1
1.0
1.2
1.0
1.0
1.0
1.0
1.1
1.0
1.0
1.0
(Phases)
n.a.
n.a.
n.a.
41.0
57.1
n.a.
n.a.
n.a.
28.2
58.4
n.a.
n.a.
n.a.
15.7
52.6
31.5
12.6
10.5
13.1
42.4
24.8
9.0
7.0
11.1
35.4
21.9
7.0
6.0
7.5
26.4
9.0
5.2
4.5
15.1
21.8
[mGy]
n.a.
n.a.
n.a.
36.9
56.3
n.a.
n.a.
n.a.
26.7
55.6
n.a.
n.a.
n.a.
15.4
53.2
28.3
10.7
8.5
13.2
43.7
21.9
7.9
6.1
10.8
35.7
23.7
6.2
5.4
7.7
26.2
7.5
4.2
3.6
10.9
21.9
[mGy]
Length Series CTDIw16 CTDIvol16
n.a.
n.a.
n.a.
406
676
n.a.
n.a.
n.a.
298
881
n.a.
n.a.
n.a.
201
764
383
342
194
147
582
279
219
116
116
452
297
148
77
68
302
90
71
46
137
227
[mGy*cm]
39.2
20.9
18.4
n.a.
n.a.
30.3
15.6
14.8
n.a.
n.a.
15.4
10.1
7.7
n.a.
n.a.
17.2
6.7
5.5
n.a.
n.a.
13.6
4.8
3.7
n.a.
n.a.
11.8
3.8
3.1
n.a.
n.a.
5.2
2.9
2.5
n.a.
n.a.
[mGy]
38.4
17.9
15.4
n.a.
n.a.
32.4
12.6
10.9
n.a.
n.a.
16.7
8.3
6.2
n.a.
n.a.
15.2
5.6
4.5
n.a.
n.a.
11.7
4.1
3.2
n.a.
n.a.
12.7
3.3
2.8
n.a.
n.a.
4.3
2.3
2.0
n.a.
n.a.
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
230
751
417
n.a.
n.a.
474
568
368
n.a.
n.a.
294
328
180
n.a.
n.a.
208
180
102
n.a.
n.a.
151
115
61
n.a.
n.a.
160
79
40
n.a.
n.a.
52
39
25
n.a.
n.a.
[mGy*cm]
DLP32
4.4
10.9
5.8
1.1
1.8
9.5
8.5
5.2
0.8
2.3
6.4
5.4
2.8
0.6
2.1
7.1
4.7
2.6
0.5
1.9
7.5
4.4
2.2
0.5
1.8
10.7
3.9
1.9
0.5
2.1
4.1
2.9
1.6
1.3
2.1
[mSv]
E (m.)
DLP32
4.9
15.0
6.9
1.2
2.0
10.7
12.3
6.8
0.9
2.6
7.3
7.9
3.7
0.6
2.3
8.0
6.8
3.3
0.5
2.1
8.4
6.4
2.8
0.5
2.0
12.0
5.6
2.4
0.5
2.3
4.6
4.2
2.1
1.4
2.4
n.a.
n.a.
n.a.
448
980
n.a.
n.a.
n.a.
311
1099
n.a.
n.a.
n.a.
201
809
383
407
196
147
604
279
260
120
116
470
297
177
81
68
323
90
77
46
137
233
234
1236
514
n.a.
n.a.
474
848
381
n.a.
n.a.
294
433
186
n.a.
n.a.
208
214
103
n.a.
n.a.
151
136
63
n.a.
n.a.
160
94
42
n.a.
n.a.
52
43
25
n.a.
n.a.
4.4
17.9
7.1
1.2
2.6
9.5
12.7
5.4
0.8
2.9
6.4
7.2
2.9
0.6
2.2
7.1
5.6
2.6
0.5
2.0
7.5
5.2
2.2
0.5
1.9
10.7
4.6
1.9
0.5
2.3
4.1
3.1
1.6
1.3
2.2
[mSv]
E (m.)
5.0
24.7
8.6
1.3
2.9
10.7
18.4
7.0
0.9
3.1
7.3
10.3
3.8
0.6
2.5
8.0
8.1
3.3
0.5
2.2
8.4
7.5
2.9
0.5
2.1
12.0
6.7
2.5
0.5
2.5
4.6
4.4
2.1
1.4
2.4
[mSv]
E (f.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Statistics
796
791
798
792
810
107
106
108
102
104
26
33
40
28
44
23
32
39
25
44
23
27
36
18
48
9
22
31
11
42
4
13
21
9
27
pants
149
254
613
231
1434
99
213
543
124
1391
85
140
397
71
1634
10
61
143
13
559
1
27
64
6
112
1.5%
2.5%
6.1%
2.3%
14.2%
1.0%
2.1%
5.4%
1.2%
13.8%
0.8%
1.4%
3.9%
0.7%
16.2%
0.1%
0.6%
1.4%
0.1%
5.5%
0.0%
0.3%
0.6%
0.1%
1.1%
Partici- Exams Fraction
Tab. A5 Average values from the German survey on paediatric CT, arranged by age group (for explanations of the terms and abbreviations see tab. A.7); for the purposes of comparison,
the corresponding values for adults from the previous surveys in 1999 (SSCT) and 2002 (MSCT) are also shown.
Adults
(SSCT survey
1999)
German Survey on Paediatric CT 2005/06
Average Values
IV
Type of
examination
Brain
Facial bone/sinuses
Chest
Entire abdomen
Qel
116
115
119
121
122
122
127
108
110
113
114
118
123
126
100
108
111
114
119
128
127
108
114
116
115
119
121
124
118
116
118
119
121
130
131
up to 1 year
1 to 5 years
6 to 10 years
11 to 15 years
Adults (MSCT 2002)
Adults (SSCT 1999)
Newborn
up to 1 year
1 to 5 years
6 to 10 years
11 to 15 years
Adults (MSCT 2002)
Adults (SSCT 1999)
Newborn
up to 1 year
1 to 5 years
6 to 10 years
11 to 15 years
Adults (MSCT 2002)
Adults (SSCT 1999)
Newborn
up to 1 year
1 to 5 years
6 to 10 years
11 to 15 years
Adults (MSCT 2002)
Adults (SSCT 1999)
Newborn
up to 1 year
1 to 5 years
6 to 10 years
11 to 15 years
Adults (MSCT 2002)
Adults (SSCT 1999)
381
285
149
167
133
118
61
228
200
125
87
61
53
45
191
163
90
69
55
52
44
239
123
86
78
68
46
81
327
317
284
231
197
162
128
[kV] [mAs]
U
Newborn
Age group
2.4
1.2
0.9
1.0
1.1
0.9
0.8
1.5
0.7
0.7
0.7
0.7
0.6
0.6
1.4
0.7
0.7
0.7
0.7
0.7
0.6
1.9
0.9
0.8
0.8
0.8
0.8
0.9
2.2
1.4
1.3
1.3
1.2
1.2
1.2
[s]
tR
1.0
3.1
11.8
8.5
9.9
11.7
12.3
1.0
3.3
12.9
11.0
11.6
14.5
8.6
1.0
3.4
13.7
13.2
14.6
13.0
10.8
1.0
3.2
10.0
10.3
9.4
11.3
11.4
1.0
2.8
8.7
7.0
9.3
6.7
6.3
N
3.3
2.3
1.4
1.5
1.6
1.4
1.5
8.9
4.3
2.7
2.6
2.5
2.0
2.3
8.4
4.0
2.6
2.5
2.1
1.9
2.0
3.3
1.7
1.3
1.2
1.2
1.1
1.2
8.4
5.7
3.5
3.9
3.4
3.5
3.3
[mm]
1.1
1.0
1.0
1.1
1.2
1.1
1.3
1.3
1.3
1.2
1.2
1.2
1.2
1.2
1.3
1.4
1.2
1.2
1.2
1.2
1.3
1.3
1.1
1.2
1.2
1.1
1.2
1.4
1.0
1.0
1.0
1.0
1.0
1.0
1.0
3.3
2.9
1.8
2.2
2.0
2.1
2.5
8.9
6.6
4.5
4.4
4.1
3.7
3.8
8.4
6.3
4.4
4.2
3.7
3.4
3.3
3.3
2.5
2.0
2.1
2.1
2.2
2.4
8.4
7.3
5.7
5.9
5.7
5.4
4.5
[mm]
hcol Pitch hrec
W
139
88
117
85
85
342
340
339
349
357
741
740
747
812
746
386 1638
482 1804
437 1740
434 1563
575 2000
46
43
46
43
50
-100
-103
-102
-127
-88
423 1995
424 2042
428 2023
523 2273
399 1850
37
37
46
36
36
C
Window
Examination parameters
6.0
13.5
15.9
11.7
11.1
9.7
8.3
40.7
41.9
35.9
29.0
25.1
19.6
14.2
29.8
31.0
26.0
20.4
16.4
12.3
10.1
9.1
10.2
11.4
9.8
9.1
7.3
8.3
12.3
13.2
13.9
12.8
11.9
10.7
9.8
[cm]
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.6
1.5
1.2
1.2
1.1
1.2
1.1
1.2
1.0
1.0
1.0
1.0
1.0
1.0
1.1
1.0
1.0
1.0
1.0
1.0
1.0
1.5
1.3
1.1
1.0
1.1
1.0
1.0
(Phases)
n.a.
n.a.
n.a.
31.5
24.8
21.9
9.0
n.a.
n.a.
n.a.
12.6
9.0
7.0
5.2
n.a.
n.a.
n.a.
10.5
7.0
6.0
4.5
41.0
28.5
15.7
13.1
11.1
7.5
15.1
57.1
58.9
52.6
42.4
35.4
26.4
21.8
[mGy]
n.a.
n.a.
n.a.
28.3
21.9
23.7
7.5
n.a.
n.a.
n.a.
10.7
7.9
6.2
4.2
n.a.
n.a.
n.a.
8.5
6.1
5.4
3.6
36.9
26.9
15.4
13.2
10.8
7.7
10.9
56.3
61.1
53.2
43.7
35.7
26.2
21.9
[mGy]
Length Series CTDIw16 CTDIvol16
n.a.
n.a.
n.a.
383
279
297
90
n.a.
n.a.
n.a.
342
219
148
71
n.a.
n.a.
n.a.
194
116
77
46
406
298
201
147
116
68
137
676
881
764
582
452
302
227
[mGy*cm]
39.2
30.5
15.4
17.2
13.6
11.8
5.2
20.9
15.6
10.1
6.7
4.8
3.8
2.9
18.4
14.9
7.7
5.5
3.7
3.1
2.5
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy]
38.4
32.6
16.7
15.2
11.7
12.7
4.3
17.9
12.7
8.3
5.6
4.1
3.3
2.3
15.4
11.0
6.2
4.5
3.2
2.8
2.0
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
230
474
294
208
151
160
52
751
568
328
180
115
79
39
416
368
180
102
61
40
25
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy*cm]
DLP32
4.4
9.5
6.4
7.1
7.5
10.7
4.1
10.9
8.5
5.4
4.7
4.4
3.9
2.9
5.8
5.2
2.8
2.6
2.2
1.9
1.6
1.1
0.8
0.6
0.5
0.5
0.5
1.3
1.8
2.3
2.1
1.9
1.8
2.1
2.1
[mSv]
E (m.)
DLP32
4.9
10.7
7.3
8.0
8.4
12.0
4.6
15.0
12.3
7.9
6.8
6.4
5.6
4.2
6.9
6.8
3.7
3.3
2.8
2.4
2.1
1.2
0.9
0.6
0.5
0.5
0.5
1.4
2.0
2.5
2.3
2.1
2.0
2.3
2.4
n.a.
n.a.
n.a.
383
279
297
90
n.a.
n.a.
n.a.
407
260
177
77
n.a.
n.a.
n.a.
196
120
81
46
448
311
201
147
116
68
137
981
1099
809
604
470
323
233
234
474
294
208
151
160
52
1236
848
433
214
136
94
43
514
381
186
103
63
42
25
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
4.4
9.5
6.4
7.1
7.5
10.7
4.1
17.9
12.7
7.2
5.6
5.2
4.6
3.1
7.1
5.4
2.9
2.6
2.2
1.9
1.6
1.2
0.8
0.6
0.5
0.5
0.5
1.3
2.6
2.9
2.2
2.0
1.9
2.3
2.2
[mSv]
E (m.)
5.0
10.7
7.3
8.0
8.4
12.0
4.6
24.7
18.4
10.3
8.1
7.5
6.7
4.4
8.6
7.0
3.8
3.3
2.9
2.5
2.1
1.3
0.9
0.6
0.5
0.5
0.5
1.4
2.9
3.2
2.5
2.2
2.1
2.5
2.4
[mSv]
E (f.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Statistics
796
107
26
23
23
9
4
791
106
33
32
27
22
13
798
108
40
39
36
31
21
792
102
28
25
18
11
9
810
104
44
44
48
42
27
pants
149
99
85
10
1
254
213
140
61
27
613
543
397
143
64
231
124
71
13
6
1434
1391
1634
559
112
1.5%
1.0%
0.8%
0.1%
0.0%
2.5%
2.1%
1.4%
0.6%
0.3%
6.1%
5.4%
3.9%
1.4%
0.6%
2.3%
1.2%
0.7%
0.1%
0.1%
14.2%
13.8%
16.2%
5.5%
1.1%
Partici- Exams Fraction
Tab. A6 Average values from the German survey on paediatric CT, arranged by type of examination (for explanation of the terms and abbreviations see tab. A.7); for the purposes of
comparison, the corresponding values for adults from the previous surveys in 1999 (SSCT) and 2002 (MSCT) are also shown.
Spine
German Survey on Paediatric CT 2005/06
Average Values
V
Age group
Newborn
up to 1 year
2 to 5 years
6 to 10 years
Qel
120
80
80
90
118
120
105
100
120
120
120
120
100
120
120
120
120
105
120
120
120
120
120
120
120
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
rotation time (in s)
number of slices acquired simultaneously per rotation
slice collimation (in mm)
pitch factor
reconstructed slice thickness (in mm)
window settings (C=centre, W=width)
tR
N
hcol
Pitch
hrec
Window
0.7
1.0
1.0
0.7
1.0
0.8
1.0
1.0
0.7
1.0
0.8
1.0
1.0
0.7
1.0
0.8
1.0
1.0
0.8
1.0
1.3
1.0
1.0
0.8
1.0
1.1
3.0
3.0
1.3
4.5
1.3
3.0
3.0
1.3
4.5
1.3
3.0
3.0
1.3
4.5
1.3
3.0
2.9
1.3
4.5
2.0
3.0
3.0
2.0
3.5
[mm]
W
76
350
350
76
328
350
80
310
350
80
320
350
80
320
350
DLP32
CTDIvol32
CTDIw32
DLP16
CTDIvol16
CTDIw16
Series
12.3
30.0
24.1
9.3
13.0
10.0
26.8
18.1
8.1
12.0
10.0
22.0
15.0
7.1
11.0
9.0
17.3
10.0
6.0
10.0
7.0
13.0
8.8
5.0
8.7
[cm]
n.a.
n.a.
n.a.
7.1
41.3
12.9
7.8
4.7
5.7
22.9
9.3
5.0
3.7
4.8
19.3
8.7
4.7
3.4
3.5
15.6
8.7
4.3
2.1
3.3
14.1
[mGy]
n.a.
n.a.
n.a.
7.8
44.4
11.7
6.0
3.7
5.5
29.3
8.7
4.2
3.0
6.1
21.6
6.3
4.0
2.6
4.5
16.9
5.8
3.1
2.0
4.3
16.1
[mGy]
n.a.
n.a.
n.a.
94
588
147
220
98
68
394
105
103
60
51
271
71
87
36
37
179
59
49
25
40
162
[mGy*cm]
7.3
6.7
4.3
n.a.
n.a.
6.9
4.5
2.4
n.a.
n.a.
5.3
2.7
2.0
n.a.
n.a.
5.1
2.5
1.8
n.a.
n.a.
5.1
2.2
1.1
n.a.
n.a.
[mGy]
7.4
6.5
4.0
n.a.
n.a.
6.4
3.2
2.0
n.a.
n.a.
5.1
2.5
1.6
n.a.
n.a.
3.4
2.3
1.4
n.a.
n.a.
3.4
1.8
1.0
n.a.
n.a.
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
dose-length product for the 32 cm body phantom (in mGy x cm)
volume CTDI for the 32 cm body phantom (in mGy)
weighted CTDI for the 32 cm body phantom (in mGy)
dose-length product for the 16 cm head phantom (in mGy x cm)
volume CTDI for the 16 cm head phantom (in mGy)
weighted CTDI for the 16 cm head phantom (in mGy)
number of scan series (=phases)
length of the imaged body section (=net scan length) (in cm)
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
(Phases)
Length Series CTDIw16 CTDIvol16
Length
213 1500
40
-400
240 1500
35
400 1500
40
-400
300 1500
35
325 1500
40
-400
325 1525
35
300 1500
40
-400
400 1800
35
300 1500
40
-250
400 1500
35
C
Window
Tab. A7 First quartile values from the German survey on paediatric CT, arranged by age group.
electrical tube-current-time product (in mAs)
0.8
1.3
1.3
0.8
1.5
0.9
1.2
0.9
0.8
1.5
1.0
1.4
0.9
0.8
1.5
1.0
0.9
0.8
0.8
1.5
0.8
1.5
0.8
0.8
1.5
[mm]
hcol Pitch hrec
Examination parameters
tube potential (in kV)
2.5
2.0
3.5
2.0
2.0
1.5
3.5
3.0
2.0
2.0
1.5
2.0
4.0
2.5
2.0
4.0
4.0
4.0
3.0
2.0
12.3
1.0
1.0
1.0
1.0
N
Qel
0.8
0.5
0.5
0.8
1.0
0.8
0.5
0.5
0.8
0.9
0.8
0.5
0.5
0.8
0.8
0.8
0.5
0.5
0.5
0.8
0.8
0.5
0.5
0.5
0.8
[s]
tR
U
90
88
56
45
230
97
56
39
38
173
74
36
30
36
126
60
34
28
30
100
59
30
23
23
80
[kV] [mAs]
U
Brain
Type of examination
Explanation of terms and abbreviations
11 to 15 years
German Survey on Paediatric CT 2005/06
1st Quartile
120
204
112
n.a.
n.a.
80
117
55
n.a.
n.a.
54
58
30
n.a.
n.a.
41
47
19
n.a.
n.a.
35
28
14
n.a.
n.a.
[mGy*cm]
DLP32
Fraction
Exams
DLP32
3.0
5.2
2.3
0.3
1.8
3.2
4.3
1.5
0.2
1.4
3.0
2.6
1.4
0.2
1.2
2.9
2.8
1.3
0.3
1.3
2.8
2.7
1.1
0.4
1.6
120
215
112
n.a.
n.a.
80
124
58
n.a.
n.a.
54
58
30
n.a.
n.a.
41
52
19
n.a.
n.a.
35
28
14
n.a.
n.a.
2.6
3.8
1.8
0.3
1.6
2.8
3.1
1.2
0.2
1.3
2.6
1.9
1.2
0.2
1.1
2.6
2.4
1.0
0.3
1.3
2.5
1.9
0.9
0.4
1.6
[mSv]
3.0
5.5
2.3
0.3
1.8
3.2
4.5
1.6
0.2
1.4
3.0
2.8
1.5
0.2
1.2
2.9
3.4
1.3
0.3
1.4
2.8
2.7
1.1
0.4
1.7
[mSv]
E (f.)
26
33
40
28
44
23
32
39
25
44
23
27
36
18
48
9
22
31
11
42
4
13
21
9
27
pants
149
254
613
231
1434
99
213
543
124
1391
85
140
397
71
1634
10
61
143
13
559
1
27
64
6
112
age group with all paediatric CT examinations = 100%
fraction of that particular type of examination and
type of examination and age group
number of annual examinations performed for that
type of examination in that age group
Statistics
1.5%
2.5%
6.1%
2.3%
14.2%
1.0%
2.1%
5.4%
1.2%
13.8%
0.8%
1.4%
3.9%
0.7%
16.2%
0.1%
0.6%
1.4%
0.1%
5.5%
0.0%
0.3%
0.6%
0.1%
1.1%
Partici- Exams Fraction
number of scanners applying that particular
effective dose for females (in mSv)
effective dose for males (in mSv)
120
215
112
94
588
147
227
100
68
394
105
105
60
51
278
71
100
36
37
183
59
49
25
40
170
E (m.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Participants
E (f.)
E (m.)
2.6
3.6
1.8
0.3
1.6
2.8
3.0
1.2
0.2
1.3
2.6
1.8
1.1
0.2
1.1
2.6
1.9
1.0
0.3
1.2
2.5
1.9
0.9
0.4
1.5
[mSv]
E (m.)
VI
Age group
Newborn
up to 1 year
2 to 5 years
6 to 10 years
Qel
120
120
100
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
rotation time (in s)
number of slices acquired simultaneously per rotation
slice collimation (in mm)
pitch factor
reconstructed slice thickness (in mm)
window settings (C=centre, W=width)
tR
N
hcol
Pitch
hrec
Window
0.8
1.4
1.2
0.9
1.0
1.0
1.3
1.3
0.9
1.0
1.1
1.1
1.1
0.8
1.0
0.9
1.2
1.1
0.8
1.0
1.5
1.1
1.2
0.9
1.0
2.0
5.0
5.0
2.0
5.0
2.0
5.0
5.0
2.0
5.0
2.0
5.0
4.0
2.0
5.0
2.0
3.7
3.0
3.0
5.0
2.5
3.0
3.0
3.0
5.0
[mm]
W
80
350
400
80
350
400
80
350
400
80
350
400
83
350
400
DLP32
CTDIvol32
CTDIw32
DLP16
CTDIvol16
CTDIw16
Series
16.0
36.6
26.0
10.0
14.0
12.0
30.0
20.0
9.0
13.0
11.0
25.0
15.8
8.5
12.0
10.0
20.0
12.0
7.0
10.8
8.0
14.0
10.0
9.0
10.0
[cm]
n.a.
n.a.
n.a.
13.1
51.6
31.3
12.4
8.1
11.7
40.5
14.9
7.5
5.7
10.1
28.6
9.8
5.7
4.7
5.5
21.9
8.8
4.7
4.0
4.6
17.5
[mGy]
n.a.
n.a.
n.a.
12.9
54.6
23.8
9.1
6.5
10.7
41.3
11.8
6.5
4.6
10.4
28.6
11.8
4.8
3.9
7.1
21.9
6.2
4.4
3.1
4.5
18.0
[mGy]
n.a.
n.a.
n.a.
164
763
259
301
148
114
536
160
181
95
114
374
195
104
68
72
252
62
64
35
51
181
[mGy*cm]
11.1
9.4
6.4
n.a.
n.a.
17.1
6.5
4.2
n.a.
n.a.
7.6
4.0
3.1
n.a.
n.a.
5.4
3.3
2.7
n.a.
n.a.
5.1
2.7
2.0
n.a.
n.a.
[mGy]
10.8
8.0
5.9
n.a.
n.a.
13.5
5.0
3.2
n.a.
n.a.
6.1
3.4
2.3
n.a.
n.a.
6.8
2.5
2.3
n.a.
n.a.
3.5
2.3
1.6
n.a.
n.a.
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
dose-length product for the 32 cm body phantom (in mGy x cm)
volume CTDI for the 32 cm body phantom (in mGy)
weighted CTDI for the 32 cm body phantom (in mGy)
dose-length product for the 16 cm head phantom (in mGy x cm)
volume CTDI for the 16 cm head phantom (in mGy)
weighted CTDI for the 16 cm head phantom (in mGy)
number of scan series (=phases)
length of the imaged body section (=net scan length) (in cm)
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
(Phases)
Length Series CTDIw16 CTDIvol16
Length
425 2000
50
40
500 2000
36
500 2000
40
40
500 2000
35
475 1600
50
40
425 2000
35
500 1500
40
40
500 2000
35
500 1750
50
40
450 1700
35
C
Window
Tab. A8 Median values from the German survey on paediatric CT, arranged by age group.
electrical tube-current-time product (in mAs)
1.0
1.5
1.5
1.0
2.5
1.3
1.5
1.5
1.0
3.1
1.3
1.5
1.5
1.0
2.5
1.3
1.5
1.5
0.8
2.8
1.1
1.5
1.5
0.8
2.5
[mm]
hcol Pitch hrec
Examination parameters
tube potential (in kV)
11.0
10.0
16.0
5.0
4.0
4.0
10.0
16.0
6.0
4.0
4.0
10.0
16.0
11.0
4.0
16.0
16.0
16.0
16.0
4.0
16.0
10.0
10.0
16.0
4.0
N
Qel
0.9
0.5
0.5
0.8
1.0
1.0
0.5
0.5
0.8
1.0
1.0
0.5
0.5
0.8
1.0
0.8
0.5
0.5
0.8
1.0
0.8
0.5
0.5
0.8
1.0
[s]
tR
U
140
114
87
77
300
167
81
58
70
235
100
54
49
49
200
90
47
39
40
150
60
34
30
45
110
[kV] [mAs]
U
Brain
Type of examination
Explanation of terms and abbreviations
11 to 15 years
German Survey on Paediatric CT 2005/06
Median
207
336
166
n.a.
n.a.
143
157
83
n.a.
n.a.
76
89
52
n.a.
n.a.
113
57
38
n.a.
n.a.
35
36
18
n.a.
n.a.
[mGy*cm]
DLP32
Fraction
Exams
DLP32
4.9
7.9
3.4
0.5
2.3
6.0
6.2
2.6
0.4
1.9
4.5
5.5
1.9
0.5
1.6
6.5
4.0
1.9
0.5
2.0
3.6
3.6
1.6
0.5
1.8
207
339
166
n.a.
n.a.
143
164
83
n.a.
n.a.
76
95
54
n.a.
n.a.
113
62
38
n.a.
n.a.
35
36
18
n.a.
n.a.
4.3
5.6
2.6
0.4
2.2
5.3
4.3
2.0
0.4
1.8
4.0
4.1
1.5
0.5
1.6
5.8
3.1
1.5
0.5
1.8
3.2
2.9
1.2
0.5
1.7
[mSv]
4.9
8.1
3.4
0.5
2.4
6.0
6.2
2.6
0.4
2.0
4.5
5.9
1.9
0.5
1.8
6.5
4.5
2.0
0.5
2.0
3.6
4.2
1.6
0.5
1.9
[mSv]
E (f.)
26
33
40
28
44
23
32
39
25
44
23
27
36
18
48
9
22
31
11
42
4
13
21
9
27
pants
149
254
613
231
1434
99
213
543
124
1391
85
140
397
71
1634
10
61
143
13
559
1
27
64
6
112
age group with all paediatric CT examinations = 100%
fraction of that particular type of examination and
type of examination and age group
number of annual examinations performed for that
type of examination in that age group
Statistics
1.5%
2.5%
6.1%
2.3%
14.2%
1.0%
2.1%
5.4%
1.2%
13.8%
0.8%
1.4%
3.9%
0.7%
16.2%
0.1%
0.6%
1.4%
0.1%
5.5%
0.0%
0.3%
0.6%
0.1%
1.1%
Partici- Exams Fraction
number of scanners applying that particular
effective dose for females (in mSv)
effective dose for males (in mSv)
207
339
166
164
789
259
309
148
114
539
160
184
98
114
411
195
118
70
72
264
62
64
35
51
190
E (m.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Participants
E (f.)
E (m.)
4.3
5.5
2.6
0.4
2.1
5.3
4.3
2.0
0.4
1.8
4.0
3.8
1.4
0.5
1.5
5.8
2.8
1.5
0.5
1.8
3.2
2.5
1.2
0.5
1.7
[mSv]
E (m.)
VII
Age group
Newborn
up to 1 year
2 to 5 years
6 to 10 years
Qel
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
Brain
Facial bone/sinuses
Chest
Entire abdomen
Spine
rotation time (in s)
number of slices acquired simultaneously per rotation
slice collimation (in mm)
pitch factor
reconstructed slice thickness (in mm)
window settings (C=centre, W=width)
tR
N
hcol
Pitch
hrec
Window
1.4
1.5
1.5
1.5
1.0
1.5
1.5
1.5
1.5
1.0
1.5
1.5
1.5
1.3
1.0
1.5
1.5
1.5
0.9
1.0
1.5
1.5
1.5
1.5
1.0
2.0
5.0
5.5
3.0
7.5
3.0
5.0
5.0
3.0
8.0
3.0
5.0
5.0
3.0
7.6
3.0
5.0
5.0
3.0
7.5
3.0
5.0
4.0
3.0
5.0
[mm]
W
88
380
1250
84
365
1450
95
350
1325
95
350
1350
96
350
1325
DLP32
CTDIvol32
CTDIw32
DLP16
CTDIvol16
CTDIw16
Series
16.8
40.0
30.0
13.6
14.6
12.0
31.6
22.7
10.0
13.5
12.5
28.1
17.2
10.8
12.5
10.0
20.0
13.0
8.5
11.0
9.3
15.0
10.6
10.0
10.8
[cm]
n.a.
n.a.
n.a.
22.5
65.2
47.3
16.3
13.6
18.1
55.5
38.6
10.7
8.7
14.2
51.4
39.2
8.6
7.1
9.4
38.5
9.1
5.5
5.6
10.7
26.9
[mGy]
n.a.
n.a.
n.a.
18.8
64.5
37.3
13.7
11.9
16.2
58.0
33.4
8.3
8.4
12.3
49.0
39.2
6.8
6.9
10.8
33.6
7.8
4.6
4.2
7.1
26.1
[mGy]
n.a.
n.a.
n.a.
243
920
524
477
257
162
711
483
261
137
132
611
564
164
93
84
393
92
81
47
58
275
[mGy*cm]
20.4
12.0
11.1
n.a.
n.a.
26.2
8.8
7.2
n.a.
n.a.
21.6
6.1
4.5
n.a.
n.a.
19.6
4.9
3.8
n.a.
n.a.
5.2
3.1
3.2
n.a.
n.a.
[mGy]
17.9
10.1
8.0
n.a.
n.a.
22.6
7.4
6.0
n.a.
n.a.
20.3
4.7
4.4
n.a.
n.a.
22.8
3.9
3.8
n.a.
n.a.
4.4
2.5
2.1
n.a.
n.a.
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
dose-length product for the 32 cm body phantom (in mGy x cm)
volume CTDI for the 32 cm body phantom (in mGy)
weighted CTDI for the 32 cm body phantom (in mGy)
dose-length product for the 16 cm head phantom (in mGy x cm)
volume CTDI for the 16 cm head phantom (in mGy)
weighted CTDI for the 16 cm head phantom (in mGy)
number of scan series (=phases)
length of the imaged body section (=net scan length) (in cm)
1.0
1.5
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.4
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
(Phases)
Length Series CTDIw16 CTDIvol16
Length
500 2000
50
50
600 3000
40
550 2000
50
50
600 3000
40
500 2000
50
50
600 3000
40
500 2000
50
50
700 3100
40
775 2250
50
50
500 2000
40
C
Window
Tab. A9 Third quartile values from the German survey on paediatric CT, arranged by age group.
electrical tube-current-time product (in mAs)
1.9
5.0
5.0
1.5
5.0
2.3
5.0
5.0
1.5
5.0
2.0
3.8
2.5
1.3
5.0
1.5
2.5
2.5
1.3
5.0
1.9
3.0
3.0
1.0
5.0
[mm]
hcol Pitch hrec
Examination parameters
tube potential (in kV)
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
16.0
12.0
16.0
16.0
16.0
16.0
13.0
16.0
16.0
16.0
16.0
8.0
16.0
16.0
16.0
16.0
8.0
N
Qel
1.0
0.8
0.8
1.0
1.5
1.0
0.8
0.8
1.0
1.5
1.3
0.8
0.8
1.0
1.5
1.0
0.8
0.8
1.0
1.5
0.8
0.8
0.8
1.0
1.5
[s]
tR
U
200
149
110
100
350
200
111
89
100
300
200
82
67
79
266
150
66
60
53
200
62
65
64
60
158
[kV] [mAs]
U
Brain
Type of examination
Explanation of terms and abbreviations
11 to 15 years
German Survey on Paediatric CT 2005/06
3rd Quartile
294
402
244
n.a.
n.a.
306
227
128
n.a.
n.a.
278
147
73
n.a.
n.a.
282
82
49
n.a.
n.a.
52
45
26
n.a.
n.a.
[mGy*cm]
DLP32
Fraction
Exams
DLP32
7.7
9.4
4.9
0.7
2.8
11.9
8.5
4.4
0.6
2.6
14.2
6.6
3.6
0.6
2.7
23.2
5.8
2.9
0.7
2.9
5.4
5.4
2.3
0.6
2.8
294
546
259
n.a.
n.a.
306
227
128
n.a.
n.a.
278
155
76
n.a.
n.a.
282
111
55
n.a.
n.a.
52
50
26
n.a.
n.a.
6.8
8.5
3.8
0.7
2.9
10.6
7.5
3.4
0.5
2.5
12.6
4.8
2.8
0.5
2.5
20.7
4.3
2.4
0.6
2.7
4.8
3.7
1.8
0.5
2.5
[mSv]
7.7
12.3
5.0
0.7
3.2
11.9
10.8
4.4
0.6
2.8
14.2
6.9
3.6
0.6
2.7
23.2
6.2
3.1
0.7
2.9
5.4
5.4
2.3
0.6
2.8
[mSv]
E (f.)
26
33
40
28
44
23
32
39
25
44
23
27
36
18
48
9
22
31
11
42
4
13
21
9
27
pants
149
254
613
231
1434
99
213
543
124
1391
85
140
397
71
1634
10
61
143
13
559
1
27
64
6
112
age group with all paediatric CT examinations = 100%
fraction of that particular type of examination and
type of examination and age group
number of annual examinations performed for that
type of examination in that age group
Statistics
1.5%
2.5%
6.1%
2.3%
14.2%
1.0%
2.1%
5.4%
1.2%
13.8%
0.8%
1.4%
3.9%
0.7%
16.2%
0.1%
0.6%
1.4%
0.1%
5.5%
0.0%
0.3%
0.6%
0.1%
1.1%
Partici- Exams Fraction
number of scanners applying that particular
effective dose for females (in mSv)
effective dose for males (in mSv)
294
546
259
243
1007
524
489
257
162
784
483
274
137
132
640
564
191
95
84
393
92
105
47
58
275
E (m.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Participants
E (f.)
E (m.)
6.8
6.5
3.8
0.7
2.5
10.6
5.9
3.4
0.5
2.3
12.6
4.6
2.8
0.5
2.5
20.7
4.0
2.2
0.6
2.7
4.8
3.7
1.8
0.5
2.5
[mSv]
E (m.)
VIII
Age group
Newborn
Up to 1 year
2 to 5 years
6 to 10 years
Qel
1.0
4.5
[mm]
C
36
W
85
40
120
120
120
Median
3rd quartile
5%
Standard deviation
1st quartile
122
Average
110
120
3rd quartile
140
120
Median
Maximum
120
1st quartile
Minimum
90
7%
Standard deviation
140
121
Average
Maximum
120
3rd quartile
Minimum
120
Median
Standard deviation
120
8%
Average
1st quartile
119
3rd quartile
90
120
Median
140
120
1st quartile
Maximum
120
Maximum
Minimum
80
140
Minimum
1.2
1.5
1.0
0.8
3.0
0.8
1.2
1.5
1.0
0.8
3.0
0.8
1.0
0.5
3.5
5.0
2.5
1.5
8.0
0.5
9.3
8.0
4.0
2.0
3.4
5.0
2.8
1.5
32.0 10.0
1.0
6.7
8.0
4.0
1.0
32.0
1.0
1.0
1.0
1.0
1.5
0.5
1.0
1.0
1.0
1.0
1.5
0.5
5.7
7.5
5.0
4.5
10.0
2.5
5.4
5.0
5.0
3.5
8.0
2.5
46
40
35
35
43
28
36
40
35
35
43
28
70
117
84
80
76
150
60
85
88
80
76
120
1.3
1.5
1.0
0.8
3.0
0.8
1.0
0.5
7.0
13.0
4.0
2.0
3.9
5.0
2.5
1.5
64.0 10.0
1.0
1.0
1.0
1.0
1.5
0.5
1.3
1.5
1.0
0.9
3.0
0.5
1.0
0.5
8.7
12.0
4.0
2.0
3.5
5.0
3.1
1.5
32.0 10.0
1.0
1.0
1.0
1.0
1.1
0.5
2.5
28
60
37
40
35
35
88
95
80
80
500 1500
5.7
8.0
5.0
4.5
10.0
2.5
37
40
35
35
45
28
139
95
80
80
150
60
36% 10% 18%
5.9
7.6
5.0
4.5
10.0
350
300
230
413
50
1.5
1.0
1.0
3.0
0.8
0.5
16.0
4.0
2.0
5.0
2.5
1.5
32.0 10.0
1.0
1.0
1.0
1.0
1.5
0.6
7.5
5.0
4.5
10.0
2.5
40
36
35
64
20
96
83
80
1500
60
29% 44% 100% 74% 12% 33% 16% 176%
284
300
235
173
400
50
39% 45% 102% 71% 11%
231
266
200
126
360
25
44% 48% 125% 75% 13% 38% 146% 175%
197
200
150
100
320
25
162
158
110
80
300
115
120
3rd quartile
3.3
[mm]
Window
12% 51% 44% 112% 66% 16% 38% 12% 19%
120
Median
6.3
hcol Pitch hrec
Examination parameters
Standard deviation
120
1st quartile
[s]
1.2
N
52% 46% 113% 63% 15% 31% 12% 16%
128
tR
Average
90
140
Maximum
9%
Standard deviation
Minimum
116
[kV] [mAs]
U
Average
Statistical quantity
14.6
14.0
13.0
20.0
7.2
15%
13.9
13.5
13.0
12.0
20.0
7.2
14%
12.8
12.5
12.0
11.0
15.0
7.2
11%
11.9
11.0
10.8
10.0
15.0
7.2
13%
10.7
10.8
10.0
8.7
12.0
7.2
14%
9.8
[cm]
1.0
1.0
1.0
2.0
1.0
18%
1.1
1.0
1.0
1.0
1.5
1.0
12%
1.0
1.0
1.0
1.0
2.0
1.0
18%
1.1
1.0
1.0
1.0
2.0
1.0
18%
1.0
1.0
1.0
1.0
1.5
1.0
13%
1.0
(Phases)
65.2
51.6
41.3
113.0
10.9
37%
52.6
55.5
40.5
22.9
113.0
10.9
53%
42.4
51.4
28.6
19.3
83.0
4.8
56%
35.4
38.5
21.9
15.6
83.0
4.8
62%
26.4
26.9
17.5
14.1
54.4
3.9
58%
21.8
[mGy]
64.5
54.6
44.4
113.0
10.9
35%
53.2
58.0
41.3
29.3
113.0
10.9
51%
43.7
49.0
28.6
21.6
83.0
4.8
53%
35.7
33.6
21.9
16.9
83.0
4.8
62%
26.2
26.1
18.0
16.1
54.4
3.9
55%
21.9
[mGy]
Length Series CTDIw16 CTDIvol16
920
763
588
1638
178
36%
764
711
536
394
1424
132
49%
582
611
374
271
1186
60
55%
452
393
252
179
896
48
66%
302
275
181
162
632
34
58%
227
[mGy*cm]
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy]
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy*cm]
DLP32
2.5
2.1
1.6
4.7
0.5
37%
2.1
2.3
1.8
1.3
4.8
0.4
50%
1.9
2.5
1.5
1.1
4.6
0.2
56%
1.8
2.7
1.8
1.2
6.0
0.3
66%
2.1
2.5
1.7
1.5
5.8
0.3
61%
2.1
[mSv]
E (m.)
DLP32
2.8
2.3
1.8
5.2
0.5
37%
2.3
2.6
1.9
1.4
5.3
0.5
50%
2.1
2.7
1.6
1.2
5.0
0.3
56%
2.0
2.9
2.0
1.3
6.6
0.4
66%
2.3
2.8
1.8
1.6
6.3
0.3
61%
2.4
1007
789
588
1638
178
40%
809
784
539
394
1424
132
51%
604
640
411
278
1186
60
54%
470
393
264
183
1380
48
78%
323
275
190
170
632
34
56%
233
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
2.9
2.2
1.6
4.7
0.5
40%
2.2
2.5
1.8
1.3
4.8
0.4
51%
2.0
2.5
1.6
1.1
4.6
0.2
55%
1.9
2.7
1.8
1.3
9.6
0.3
78%
2.3
2.5
1.7
1.6
5.8
0.3
58%
2.2
[mSv]
E (m.)
3.2
2.4
1.8
5.2
0.5
40%
2.5
2.8
2.0
1.4
5.3
0.5
51%
2.2
2.7
1.8
1.2
5.0
0.3
55%
2.1
2.9
2.0
1.4
10.6
0.4
78%
2.5
2.8
1.9
1.7
6.3
0.3
58%
2.4
[mSv]
E (f.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Tab. A10 Results from the German survey on paediatric CT for brain examinations (for explanations of the terms and abbreviations see tab. A.7).
11 to 15 years
German Survey on Paediatric CT 2005/06
Type of Examination: Brain
Statistics
44
44
48
42
27
pants
1434
1391
1634
559
112
14.2%
13.8%
16.2%
5.5%
1.1%
Partici- Exams Fraction
IX
Age group
Newborn
Up to 1 year
2 to 5 years
6 to 10 years
Qel
11.4
1.4
C
W
3rd quartile
3rd quartile
3rd quartile
80
130
120
120
120
118
7%
100
140
120
120
120
Minimum
Maximum
1st quartile
Median
3rd quartile
Average
Standard deviation
Minimum
Maximum
1st quartile
Median
3rd quartile
0.8
1.0
0.8
0.8
1.5
0.5
0.8
1.0
0.8
10.0
16.0
6.0
2.0
32.0
1.0
10.3
16.0
11.0
2.5
1.3
1.5
1.0
0.8
3.0
0.5
1.2
1.3
1.0
0.8
3.0
0.8
1.2
1.5
0.9
0.7
5.0
0.3
1.2
1.3
0.8
0.7
5.0
0.3
2.0
3.0
2.0
1.3
4.0
0.5
2.1
3.0
2.0
1.3
3.2
1.0
2.1
3.0
3.0
500
350
270
423 1995
600 3000
500 2000
300 1500
850 3200
30
424 2042
600 3000
425 2000
325 1525
850 3200
40
53%
428 2023
700 3100
500 2000
400 1800
100
77
45
282
15
1.0
0.8
0.8
1.5
0.5
16.0
5.0
2.0
32.0
1.0
1.5
1.0
0.8
3.0
0.5
1.5
0.9
0.7
5.0
0.5
3.0
2.0
1.3
4.0
0.5
80
600 3000
500 2000
240 1500
850 3200
40
73% 29% 90% 56% 76% 51% 60% 54%
86
100
70
38
250
9
78
79
49
0.8
1.0
16.0
1.1
0.9
0.8
1.3
50
850 3200
114
120
Median
36
1.5
0.5
1.2
1.3
0.8
0.8
3.2
1.0
11% 72% 32% 91% 59% 82% 48% 59% 50%
120
1st quartile
9
250
9.4
16.0
16.0
0.8
5.0
0.5
523 2273
500 2000
450 1700
Standard deviation
120
Maximum
0.8
1.0
0.8
3.0
2.5
0.6
2.2
3.0
3.0
400 1500
Average
80
120
Minimum
68
53
40
0.5
1.0
32.0
1.2
1.5
0.9
2.0
150
850 3200
-250
113
120
Median
30
1.5
0.5
1.1
1.0
0.8
0.8
4.0
1.0
12% 84% 35% 74% 55% 92% 45% 58%
120
1st quartile
23
100
11.3
16.0
16.0
0.8
5.0
0.5
Standard deviation
105
Maximum
0.8
1.0
0.8
1.0
3.0
0.6
Average
80
120
Minimum
46
60
45
0.5
1.0
32.0
110
120
Median
23
1.5
0.5
15% 53% 39% 86% 54% 110% 42% 42% 39%
120
1st quartile
20
385
399 1850
Standard deviation
80
Maximum
2.4
[mm]
Window
Average
80
140
Minimum
1.2
[mm]
hcol Pitch hrec
Examination parameters
21% 143% 48% 92% 68% 100% 41% 83% 48%
[s]
0.9
N
Standard deviation
81
tR
108
[kV] [mAs]
U
Average
Statistical quantity
13.6
10.0
9.3
20.0
7.5
27%
11.4
10.0
9.0
8.1
17.5
6.0
27%
9.8
10.8
8.5
7.1
15.0
4.9
32%
9.1
8.5
7.0
6.0
12.5
3.5
36%
7.3
10.0
9.0
5.0
15.0
3.0
54%
8.3
[cm]
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
(Phases)
22.5
13.1
7.1
60.5
2.8
76%
15.7
18.1
11.7
5.7
35.3
1.7
72%
13.1
14.2
10.1
4.8
35.3
1.7
77%
11.1
9.4
5.5
3.5
19.9
3.3
68%
7.5
10.7
4.6
3.3
82.6
2.9
172%
15.1
[mGy]
18.8
12.9
7.8
43.9
3.6
69%
15.4
16.2
10.7
5.5
43.9
3.6
77%
13.2
12.3
10.4
6.1
35.3
4.0
66%
10.8
10.8
7.1
4.5
12.3
4.0
45%
7.7
7.1
4.5
4.3
55.1
3.2
153%
10.9
[mGy]
Length Series CTDIw16 CTDIvol16
243
164
94
731
35
80%
201
162
114
68
541
35
83%
147
132
114
51
365
32
67%
116
84
72
37
126
23
50%
68
58
51
40
875
20
202%
137
[mGy*cm]
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy]
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
[mGy*cm]
DLP32
0.7
0.4
0.3
2.0
0.1
80%
0.6
0.5
0.4
0.2
1.8
0.1
83%
0.5
0.5
0.5
0.2
1.4
0.1
66%
0.5
0.6
0.5
0.3
0.9
0.2
50%
0.5
0.5
0.5
0.4
8.3
0.2
204%
1.3
[mSv]
E (m.)
DLP32
0.7
0.5
0.3
2.2
0.1
80%
0.6
0.6
0.4
0.2
1.9
0.1
83%
0.5
0.6
0.5
0.2
1.6
0.1
66%
0.5
0.7
0.5
0.3
0.9
0.2
50%
0.5
0.6
0.5
0.4
9.0
0.2
204%
1.4
243
164
94
731
35
80%
201
162
114
68
541
35
83%
147
132
114
51
365
32
67%
116
84
72
37
126
23
50%
68
58
51
40
875
20
202%
137
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
0.7
0.4
0.3
2.0
0.1
80%
0.6
0.5
0.4
0.2
1.8
0.1
83%
0.5
0.5
0.5
0.2
1.4
0.1
66%
0.5
0.6
0.5
0.3
0.9
0.2
50%
0.5
0.5
0.5
0.4
8.3
0.2
204%
1.3
[mSv]
E (m.)
0.7
0.5
0.3
2.2
0.1
80%
0.6
0.6
0.4
0.2
1.9
0.1
83%
0.5
0.6
0.5
0.2
1.6
0.1
66%
0.5
0.7
0.5
0.3
0.9
0.2
50%
0.5
0.6
0.5
0.4
9.0
0.2
204%
1.4
[mSv]
E (f.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Tab. A11 Results from the German survey on paediatric CT for facial bone/sinuses examinations (for explanations of the terms and abbreviations see tab. A.7).
11 to 15 years
German Survey on Paediatric CT 2005/06
Type of Examination: Facial Bone/Sinuses
Statistics
28
25
18
11
9
pants
231
124
71
13
6
2.3%
1.2%
0.7%
0.1%
0.1%
Partici- Exams Fraction
X
Age group
Newborn
Up to 1 year
2 to 5 years
6 to 10 years
Qel
10.8
1.3
C
W
3rd quartile
3rd quartile
4.0
3rd quartile
3rd quartile
80
140
120
120
120
Minimum
Maximum
1st quartile
Median
3rd quartile
110
87
56
203
26
90
89
58
39
0.8
0.5
0.5
1.5
0.5
0.7
0.8
0.5
0.5
1.0
16.0
16.0
3.5
64.0
1.0
13.7
16.0
16.0
3.0
64.0
5.0
1.5
1.3
8.0
0.5
2.6
5.0
1.5
0.9
8.0
0.5
1.5
1.2
1.0
2.0
0.6
1.2
1.5
1.3
1.0
1.8
0.7
1.2
1.5
1.1
5.5
5.0
3.0
8.0
1.0
4.4
5.0
5.0
3.0
8.0
1.0
4.2
5.0
4.0
3.0
50
40
-400
500
-600
-100
50
40
-400
500
-600
-103
50
40
-400
500
-600
275
1325
400
350
2000
275
741
1350
400
350
2000
200
740
1325
400
350
2000
119
120
Median
1.0
0.5
2.5
2.5
1.5
1.0
6.5
0.6
747
1450
400
350
11% 46% 34% 107% 76% 25% 44% -271% 76%
120
1st quartile
23
203
13.2
16.0
16.0
0.9
1.8
0.7
-102
50
40
-400
Standard deviation
105
Maximum
0.7
0.8
0.5
4.0
5.0
0.5
3.7
5.0
3.0
2.9
275
2000
Average
80
140
Minimum
69
67
49
0.5
1.0
64.0
1.2
1.5
1.1
1.0
500
-600
114
120
Median
30
1.0
0.5
2.1
2.5
1.5
0.8
6.5
0.6
812
1250
400
13% 55% 28% 110% 78% 22% 38% -264% 77%
120
1st quartile
20
158
14.6
16.0
16.0
2.0
0.7
-127
50
40
350
Standard deviation
100
Maximum
0.7
0.8
0.5
0.5
5.0
0.5
3.4
4.0
3.0
-250
275
2000
Average
80
140
Minimum
55
60
39
28
1.0
32.0
1.2
1.5
1.2
3.0
500
-600
111
120
Median
1.0
0.3
1.9
3.0
1.5
1.0
6.0
1.0
14% 60% 30% 101% 76% 22% 40% -268% 76%
120
1st quartile
10
160
13.0
16.0
10.0
0.8
2.0
0.8
Standard deviation
100
Maximum
0.7
0.8
0.5
1.0
5.0
0.5
Average
80
140
Minimum
52
64
30
0.5
1.0
32.0
108
120
Median
23
1.0
0.3
746
15% 73% 31% 75% 76% 24% 47% -227% 73%
100
1st quartile
15
105
-88
Standard deviation
80
Maximum
3.3
[mm]
Window
Average
80
120
Minimum
2.0
[mm]
hcol Pitch hrec
Examination parameters
16% 64% 32% 90% 66% 28% 36% -334% 79%
[s]
0.6
N
Standard deviation
44
tR
100
[kV] [mAs]
U
Average
Statistical quantity
30.0
26.0
24.1
37.0
14.0
19%
26.0
22.7
20.0
18.1
30.0
15.0
17%
20.4
17.2
15.8
15.0
25.0
10.0
19%
16.4
13.0
12.0
10.0
25.0
7.0
29%
12.3
10.6
10.0
8.8
15.0
7.6
19%
10.1
[cm]
1.0
1.0
1.0
2.0
1.0
15%
1.0
1.0
1.0
1.0
2.0
1.0
16%
1.0
1.0
1.0
1.0
2.0
1.0
18%
1.0
1.0
1.0
1.0
2.0
1.0
19%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
(Phases)
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
13.6
8.1
4.7
31.0
2.0
75%
10.5
8.7
5.7
3.7
24.2
1.7
65%
7.0
7.1
4.7
3.4
17.6
1.2
69%
6.0
5.6
4.0
2.1
15.3
1.2
71%
4.5
[mGy]
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
11.9
6.5
3.7
25.5
2.0
71%
8.5
8.4
4.6
3.0
22.5
1.7
72%
6.1
6.9
3.9
2.6
21.1
1.2
78%
5.4
4.2
3.1
2.0
7.8
1.2
61%
3.6
[mGy]
Length Series CTDIw16 CTDIvol16
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
257
148
98
603
49
67%
194
137
95
60
407
30
69%
116
93
68
36
360
20
81%
77
47
35
25
146
16
71%
46
[mGy*cm]
11.1
6.4
4.3
17.2
1.9
57%
7.7
7.2
4.2
2.4
16.5
1.0
75%
5.5
4.5
3.1
2.0
14.1
1.0
69%
3.7
3.8
2.7
1.8
8.7
0.7
63%
3.1
3.2
2.0
1.1
8.7
0.7
74%
2.5
[mGy]
8.0
5.9
4.0
14.0
1.6
47%
6.2
6.0
3.2
2.0
14.0
1.0
71%
4.5
4.4
2.3
1.6
11.3
0.7
70%
3.2
3.8
2.3
1.4
10.6
0.7
73%
2.8
2.1
1.6
1.0
4.5
0.7
62%
2.0
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
244
166
112
416
53
48%
180
128
83
55
332
25
67%
102
73
52
30
203
12
67%
61
49
38
19
180
12
77%
40
26
18
14
85
9
75%
25
[mGy*cm]
DLP32
3.8
2.6
1.8
6.2
0.9
47%
2.8
3.4
2.0
1.2
8.7
0.6
70%
2.6
2.8
1.4
1.1
7.3
0.5
73%
2.2
2.2
1.5
1.0
8.6
0.4
84%
1.9
1.8
1.2
0.9
5.3
0.5
75%
1.6
[mSv]
E (m.)
DLP32
4.9
3.4
2.3
8.0
1.2
47%
3.7
4.4
2.6
1.5
11.2
0.8
70%
3.3
3.6
1.9
1.4
9.4
0.7
73%
2.8
2.9
1.9
1.3
11.1
0.5
84%
2.4
2.3
1.6
1.1
6.9
0.6
75%
2.1
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
257
148
100
603
49
66%
196
137
98
60
407
30
68%
120
95
70
36
360
20
79%
81
47
35
25
146
16
71%
46
259
166
112
475
53
53%
186
128
83
58
332
25
66%
103
76
54
30
203
12
66%
63
55
38
19
180
12
76%
42
26
18
14
85
9
75%
25
3.8
2.6
1.8
8.0
0.9
53%
2.9
3.4
2.0
1.2
8.7
0.6
69%
2.6
2.8
1.5
1.2
7.3
0.5
72%
2.2
2.4
1.5
1.0
8.6
0.4
82%
1.9
1.8
1.2
0.9
5.3
0.5
75%
1.6
[mSv]
E (m.)
5.0
3.4
2.3
10.3
1.2
53%
3.8
4.4
2.6
1.6
11.2
0.8
69%
3.3
3.6
1.9
1.5
9.4
0.7
72%
2.9
3.1
2.0
1.3
11.1
0.5
82%
2.5
2.3
1.6
1.1
6.9
0.6
75%
2.1
[mSv]
E (f.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Tab. A12 Results from the German survey on paediatric CT for chest examinations (for explanations of the terms and abbreviations see tab. A.7).
11 to 15 years
German Survey on Paediatric CT 2005/06
Type of Examination: Chest
Statistics
40
39
36
31
21
pants
613
543
397
143
64
6.1%
5.4%
3.9%
1.4%
0.6%
Partici- Exams Fraction
XI
Age group
Newborn
Up to 1 year
2 to 5 years
6 to 10 years
Qel
8.6
1.2
C
W
3rd quartile
4.0
11.6
16.0
16.0
2.5
2.5
1.5
0.9
5.0
0.6
1.2
1.5
1.2
1.0
1.6
0.8
1.2
1.5
1.1
4.1
5.0
3.7
3.0
5.0
0.6
3.7
5.0
3.0
3.0
30
46
50
40
40
50
30
43
50
50
40
122
339
365
350
328
400
300
349
380
350
350
458
300
1
120
120
120
3rd quartile
Standard deviation
Median
5%
Average
1st quartile
119
3rd quartile
90
120
Median
130
120
1st quartile
Maximum
120
Maximum
Minimum
80
130
Minimum
0.7
0.8
0.5
0.5
1.0
0.5
0.7
1.0
12.9
16.0
10.0
3.5
64.0
1.0
11.0
16.0
10.0
2.0
64.0
2.7
5.0
1.5
1.2
8.0
0.6
2.6
3.8
1.5
1.4
8.0
0.6
1.2
1.5
1.3
1.0
1.5
0.7
1.2
1.5
1.1
1.0
1.5
0.8
4.5
5.0
5.0
3.0
8.0
1.0
4.4
5.0
5.0
3.0
8.0
1.0
46
50
40
40
60
30
43
50
50
40
60
30
342
350
350
320
400
200
340
350
350
310
400
200
149
114
88
249
50
0.8
0.5
0.5
1.5
0.5
16.0
10.0
2.0
64.0
1.0
5.0
1.5
1.3
8.0
0.6
1.5
1.4
1.0
1.5
0.7
5.0
5.0
3.0
8.0
1.0
50
50
40
60
30
350
350
320
400
220
42% 35% 118% 81% 22% 43% 20% 12%
125
111
81
56
200
15
87
0.8
0.5
0.5
1.5
0.4
115
82
54
36
200
11% 45% 29% 107% 76% 22% 35% 21% 13%
120
3rd quartile
0.7
0.8
0.5
0.5
1.0
64.0
2.0
3.0
1.5
1.0
6.0
2.0
64% 37% 114% 77% 21% 40% 18% 13%
61
66
47
34
1.5
0.3
14.5
16.0
10.0
1.5
1.5
0.8
Standard deviation
120
14
126
0.6
0.8
0.5
1.0
5.0
0.8
Average
120
Standard deviation
Median
8%
Average
1st quartile
116
3rd quartile
90
120
Median
130
120
1st quartile
Maximum
120
Maximum
Minimum
80
120
Minimum
53
65
34
0.5
1.0
16.0
114
120
Median
30
1.0
0.5
357
12% 53% 41% 99% 71% 21% 37% 16% 10%
120
1st quartile
25
110
50
Standard deviation
90
Maximum
3.8
[mm]
Window
Average
80
120
Minimum
2.3
[mm]
hcol Pitch hrec
Examination parameters
17% 55% 32% 79% 61% 22% 35% 46% 13%
[s]
0.6
N
Standard deviation
45
tR
108
[kV] [mAs]
U
Average
Statistical quantity
40.0
36.6
30.0
50.0
18.0
18%
35.9
31.6
30.0
26.8
40.0
15.0
18%
29.0
28.1
25.0
22.0
35.0
15.0
19%
25.1
20.0
20.0
17.3
28.0
13.0
18%
19.6
15.0
14.0
13.0
20.0
10.0
18%
14.2
[cm]
1.5
1.0
1.0
2.4
1.0
33%
1.2
1.0
1.0
1.0
2.0
1.0
30%
1.2
1.0
1.0
1.0
2.0
1.0
23%
1.1
1.4
1.0
1.0
2.0
1.0
30%
1.2
1.0
1.0
1.0
1.5
1.0
17%
1.1
(Phases)
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
16.3
12.4
7.8
29.7
3.1
50%
12.6
10.7
7.5
5.0
24.8
0.1
70%
9.0
8.6
5.7
4.7
18.5
1.8
53%
7.0
5.5
4.7
4.3
8.8
1.2
41%
5.2
[mGy]
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
13.7
9.1
6.0
22.2
2.2
52%
10.7
8.3
6.5
4.2
27.2
0.0
77%
7.9
6.8
4.8
4.0
23.1
1.3
75%
6.2
4.6
4.4
3.1
7.8
1.6
38%
4.2
[mGy]
Length Series CTDIw16 CTDIvol16
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
477
301
220
756
49
55%
342
261
181
103
777
1
79%
219
164
104
87
705
39
95%
148
81
64
49
162
31
48%
71
[mGy*cm]
12.0
9.4
6.7
18.8
3.1
43%
10.1
8.8
6.5
4.5
16.5
1.5
49%
6.7
6.1
4.0
2.7
13.3
0.0
67%
4.8
4.9
3.3
2.5
9.0
0.9
49%
3.8
3.1
2.7
2.2
5.1
0.7
41%
2.9
[mGy]
10.1
8.0
6.5
17.5
2.9
38%
8.3
7.4
5.0
3.2
12.2
1.1
50%
5.6
4.7
3.4
2.5
13.6
0.0
71%
4.1
3.9
2.5
2.3
11.2
0.6
68%
3.3
2.5
2.3
1.8
4.5
0.9
38%
2.3
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
402
336
204
694
101
44%
328
227
157
117
410
25
52%
180
147
89
58
388
0
73%
115
82
57
47
342
19
87%
79
45
36
28
94
18
49%
39
[mGy*cm]
DLP32
6.5
5.5
3.6
11.7
1.6
44%
5.4
5.9
4.3
3.0
10.8
0.7
55%
4.7
4.6
3.8
1.8
15.8
0.0
89%
4.4
4.0
2.8
1.9
20.4
1.1
104%
3.9
3.7
2.5
1.9
6.8
1.0
57%
2.9
[mSv]
E (m.)
DLP32
9.4
7.9
5.2
16.9
2.4
44%
7.9
8.5
6.2
4.3
15.6
1.0
55%
6.8
6.6
5.5
2.6
22.8
0.0
89%
6.4
5.8
4.0
2.8
29.5
1.6
104%
5.6
5.4
3.6
2.7
9.9
1.4
57%
4.2
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
489
309
227
1512
99
78%
407
274
184
105
1553
1
112%
260
191
118
100
705
39
93%
177
105
64
49
162
31
50%
77
546
339
215
1388
101
71%
433
227
164
124
756
49
75%
214
155
95
58
777
0
106%
136
111
62
52
342
19
86%
94
50
36
28
94
18
52%
43
8.5
5.6
3.8
22.5
1.6
70%
7.2
7.5
4.3
3.1
20.6
1.3
77%
5.6
4.8
4.1
1.9
30.7
0.0
116%
5.2
4.3
3.1
2.4
20.4
1.1
101%
4.6
3.7
2.9
1.9
6.8
1.0
54%
3.1
[mSv]
E (m.)
12.3
8.1
5.5
32.5
2.4
70%
10.3
10.8
6.2
4.5
29.7
1.9
77%
8.1
6.9
5.9
2.8
44.4
0.0
116%
7.5
6.2
4.5
3.4
29.5
1.6
101%
6.7
5.4
4.2
2.7
9.9
1.4
54%
4.4
[mSv]
E (f.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Tab. A13 Results from the German survey on paediatric CT for abdomen (incl. pelvis) examinations (for explanations of the terms and abbreviations see tab. A.7).
11 to 15 years
German Survey on Paediatric CT 2005/06
Type of Examination: Entire Abdomen (incl. Pelvis)
Statistics
33
32
27
22
13
pants
254
213
140
61
27
2.5%
2.1%
1.4%
0.6%
0.3%
Partici- Exams Fraction
XII
Age group
Newborn
Up to 1 year
2 to 5 years
6 to 10 years
Qel
1.3
2.5
[mm]
C
W
575 2000
0.9
0.8
0.8
0.8
1.0
0.8
1.0
11.7
16.0
16.0
12.3
16.0
1.4
1.9
1.1
0.8
3.0
0.8
1.1
1.5
1.5
1.3
1.5
0.8
2.1
3.0
2.5
2.0
3.0
2.0
300 1500
434 1563
775 2250
500 1750
300 1500
1000 3000
55
1.1
1.0
0.8
0.8
1.0
0.8
1.0
9.9
16.0
16.0
4.0
16.0
1.6
1.5
1.3
1.0
3.0
0.8
1.2
1.5
0.9
0.8
1.5
0.8
2.0
3.0
2.0
1.3
3.0
1.0
50
270
437 1740
500 2000
500 1500
300 1500
1000 3000
120
120
120
3rd quartile
Standard deviation
Median
5%
Average
1st quartile
121
3rd quartile
110
120
Median
140
120
1st quartile
Maximum
120
Maximum
Minimum
90
140
Minimum
0.9
1.0
1.0
0.8
2.0
0.5
1.0
1.0
11.8
16.0
4.0
1.5
32.0
1.0
8.5
16.0
4.0
1.5
32.0
1.4
2.3
1.3
0.9
3.0
0.5
1.5
2.0
1.3
1.0
3.0
0.6
1.0
1.5
1.0
0.8
2.0
0.7
1.1
1.5
1.1
0.8
2.0
0.5
1.8
3.0
2.0
1.3
5.0
0.5
2.2
3.0
2.0
1.3
3.2
0.6
40
270
270
386 1638
550 2000
500 2000
400 1500
1500 4000
40
482 1804
500 2000
475 1600
325 1500
1000 4000
200
140
90
500
17
1.0
0.9
0.8
1.5
0.5
16.0
11.0
2.5
64.0
1.0
1.9
1.0
0.8
3.0
0.5
1.4
0.8
0.7
2.0
0.5
2.0
2.0
1.1
3.2
0.5
270
500 2000
425 2000
213 1500
1000 4000
40
66% 27% 113% 61% 40% 47% 63% 54%
149
200
167
97
400
53
167
1.3
1.0
0.8
2.0
0.5
119
200
100
74
400
26
70% 34% 97% 53% 32% 44% 59% 51%
133
150
90
60
225
10% 53% 36% 98% 59% 35% 49% 66% 54%
120
3rd quartile
1.5
[mm]
Window
15% 61% 71% 29% 23% 59% 35%
12.3
hcol Pitch hrec
Examination parameters
Standard deviation
120
Median
[s]
0.8
N
56% 15% 56% 49% 34% 39% 69% 55%
118
62
60
59
68
55
9%
61
tR
Average
120
1st quartile
9%
Standard deviation
90
118
Average
140
120
3rd quartile
Maximum
120
Minimum
120
Median
9%
Standard deviation
1st quartile
116
Average
90
120
3rd quartile
120
120
Median
Maximum
118
1st quartile
Minimum
110
120
Maximum
4%
Standard deviation
Minimum
118
[kV] [mAs]
U
Average
Statistical quantity
16.8
16.0
12.3
49.0
6.0
51%
15.9
12.0
12.0
10.0
20.0
6.0
31%
11.7
12.5
11.0
10.0
20.0
5.0
31%
11.1
10.0
10.0
9.0
12.0
6.9
14%
9.7
9.3
8.0
7.0
10.3
7.0
19%
8.3
[cm]
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
1.0
1.0
1.0
1.0
1.0
0%
1.0
(Phases)
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
47.3
31.3
12.9
71.5
7.3
65%
31.5
38.6
14.9
9.3
70.5
3.4
88%
24.8
39.2
9.8
8.7
47.8
5.7
77%
21.9
9.1
8.8
8.7
9.8
8.7
6%
9.0
[mGy]
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
37.3
23.8
11.7
69.8
6.5
65%
28.3
33.4
11.8
8.7
69.8
4.6
91%
21.9
39.2
11.8
6.3
52.3
5.8
86%
23.7
7.8
6.2
5.8
11.8
5.8
39%
7.5
[mGy]
Length Series CTDIw16 CTDIvol16
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
524
259
147
969
84
72%
383
483
160
105
821
52
88%
279
564
195
71
570
68
82%
297
92
62
59
175
59
63%
90
[mGy*cm]
20.4
11.1
7.3
69.1
1.8
90%
15.4
26.2
17.1
6.9
44.8
3.8
70%
17.2
21.6
7.6
5.3
44.8
2.0
94%
13.6
19.6
5.4
5.1
26.3
2.9
74%
11.8
5.2
5.1
5.1
5.4
5.1
3%
5.2
[mGy]
17.9
10.8
7.4
100.5
3.2
114%
16.7
22.6
13.5
6.4
34.9
3.6
64%
15.2
20.3
6.1
5.1
34.9
2.7
90%
11.7
22.8
6.8
3.4
26.2
3.3
83%
12.7
4.4
3.5
3.4
6.8
3.4
39%
4.3
[mGy]
CTDIw32 CTDIvol32
Dose values per scan series
DLP16
294
207
120
1979
24
127%
294
306
143
80
563
47
73%
208
278
76
54
411
27
87%
151
282
113
41
332
35
80%
160
52
35
35
102
35
64%
52
[mGy*cm]
DLP32
6.8
4.3
2.6
42.7
0.5
125%
6.4
10.6
5.3
2.8
17.1
1.6
70%
7.1
12.6
4.0
2.6
21.7
1.5
90%
7.5
20.7
5.8
2.6
22.7
2.1
87%
10.7
4.8
3.2
2.5
7.4
2.5
56%
4.1
[mSv]
E (m.)
DLP32
7.7
4.9
3.0
48.1
0.6
125%
7.3
11.9
6.0
3.2
19.2
1.8
70%
8.0
14.2
4.5
3.0
24.4
1.6
90%
8.4
23.2
6.5
2.9
25.5
2.4
87%
12.0
5.4
3.6
2.8
8.4
2.8
56%
4.6
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
n.a.
524
259
147
969
84
72%
383
483
160
105
821
52
88%
279
564
195
71
570
68
82%
297
92
62
59
175
59
63%
90
294
207
120
1979
24
127%
294
306
143
80
563
47
73%
208
278
76
54
411
27
87%
151
282
113
41
332
35
80%
160
52
35
35
102
35
64%
52
6.8
4.3
2.6
42.7
0.5
125%
6.4
10.6
5.3
2.8
17.1
1.6
70%
7.1
12.6
4.0
2.6
21.7
1.5
90%
7.5
20.7
5.8
2.6
22.7
2.1
87%
10.7
4.8
3.2
2.5
7.4
2.5
56%
4.1
[mSv]
E (m.)
7.7
4.9
3.0
48.1
0.6
125%
7.3
11.9
6.0
3.2
19.2
1.8
70%
8.0
14.2
4.5
3.0
24.4
1.6
90%
8.4
23.2
6.5
2.9
25.5
2.4
87%
12.0
5.4
3.6
2.8
8.4
2.8
56%
4.6
[mSv]
E (f.)
Dose values per examination
DLP16
[mSv] [mGy*cm] [mGy*cm]
E (f.)
Tab. A14 Results from the German survey on paediatric CT for lumbar spine examinations (for explanations of the terms and abbreviations see tab. A.7).
11 to 15 years
German Survey on Paediatric CT 2005/06
Type of Examination: Lumbar Spine
Statistics
26
23
23
9
4
pants
149
99
85
10
1
1.5%
1.0%
0.8%
0.1%
0.0%
Partici- Exams Fraction
XIII
XIV
Type of
Age group
CTDIvol16
DLP16
CTDIvol32
DLP32
(mGy)
(mGy x cm)
(mGy)
(mGy x cm)
Newborn
27
290
n.a.
n.a.
Up to 1 year
33
390
n.a.
n.a.
1 to 5 years
40
520
n.a.
n.a.
6 to 10 years
50
710
n.a.
n.a.
11 to 15 years
60
920
n.a.
n.a.
Above 15 years
60
1100
n.a.
n.a.
Newborn
9
70
n.a.
n.a.
Up to 1 year
11
95
n.a.
n.a.
1 to 5 years
13
125
n.a.
n.a.
6 to 10 years
17
180
n.a.
n.a.
11 to 15 years
20
230
n.a.
n.a.
Above 15 years
20
230
n.a.
n.a.
Facial bone/
sinuses
Brain
examination
Lumbar spine
Entire abdomen
(incl. Pelvis)
Chest
Newborn
2
25
1
12
Up to 1 year
3.5
55
1.7
28
1 to 5 years
5.5
110
2.7
55
6 to 10 years
8.5
210
4.3
105
11 to 15 years
n.a.
n.a.
6.8
205
Above 15 years
n.a.
n.a.
10
345
27
Newborn
3
55
1.5
Up to 1 year
5
145
2.5
70
1 to 5 years
8
255
4
125
6 to 10 years
13
475
6.5
240
11 to 15 years
n.a.
n.a.
10
500
Above 15 years
n.a.
n.a.
15
980
Newborn
7.5
85
3.7
42
Up to 1 year
13
165
6.5
85
1 to 5 years
20
270
10
135
6 to 10 years
32
430
16
215
11 to 15 years
n.a.
n.a.
26
380
Above 15 years
n.a.
n.a.
37
530
Tab. A15 Proposal for diagnostic reference values for paediatric CT examinations;
DLP values apply to complete examinations.
XV
Type of
examination
Age group
CTDIw16
CTDIvol16 *
CTDIvol16
DLP16
DLP16
Shrimpton
2000
Shrimpton
2000
Survey
D2005/06
Ratio
Shrimpton
2000
Survey
D2005/06
(mGy)
(mGy)
(mGy)
(mGy x cm)
(mGy x cm)
Ratio
Brain
Up to 1y
40
40
33
0.83
300
390
1.30
(BRN)
2 to 5y
60
60
40
0.67
600
520
0.87
6 to 10y
70
70
50
0.71
750
710
0.95
Chest
Up to 1y
20
13
3,5
0.27
200
55
0.28
(CHE)
2 to 5y
30
20
5,5
0.28
400
110
0.28
6 to 10y
30
20
8,5
0,43
600
210
0.35
Up to 1y
20
13
5
0.38
500
145
0.29
2 to 5y
25
17
8
0.47
610
255
0.42
6 to 10y
30
20
13
0.65
1300
475
0.37
Entire abdomen **
(ABDPE)
* Assumption: Pitch 1 with BRN and 1.5 with CHE and ABDPE
** DLP values for entire abdomen Shrimpton2000 = sum of abdomen and pelvis
Tab. A16 Comparison of the reference values proposed by us (survey D2005/06) with those given in the publication by
Shrimpton et al. (Shrimpton2000). ‘Ratio’ shows the D2005/06 values relative to the Shrimpton2000 data.
Number of examinations per year in age group
10 years
Premature Newborn 10 months
5 years
5 years =
> 2 years
to 7 years
!
10 years =
> 7 years
to 12 years
Fig. A1 Questionnaire used in phase I of the survey for the registration of examination frequencies (translated).
Please return this questionnaire at allevents (even if you don't operate a CT scanner or if
you don't perform paediatric CT examinations).
If you should dispose paediatric CT examinations at another institution: please tell us the
corresponding name and address.
(please specify)
10 months =
>3 months
to 2 years
0
Pelvis
Newborn =
appr. 3000 g
to 3 months
0
Entire abdomen (incl. pelvis)
Premature =
appr. 1000 g
0
Upper abdomen
(4)
0
Others
0
300
(3)
Chest
2500
(2)
Head
CT examinations per year
(total number)
Paediatric CT examinations per year
(total number for patients up to 12 years)
Examination range
0
0
0
0
2
2005
08
Set-up
Month/year
Lightspeed VCT
CT scanner: type
0
0
0
3
5
5
5
10
15
60
Dr. G. Stamm
[email protected]
GE
(1)
Example:
MHH
Diagn. Radiologie
30625 Hannover
Contact person for queries?
Name:
Tel. or e-mail:
CT scanner: manufacturer
Institution: address
10
10
20
20
130
Please return to:
Prof. Dr. M. Galanski
Diagnostische Radiologie
Medizinische Hochschule Hannover
Carl-Neuberg-Str. 1
30625 Hannover
Fax: 0511/532-3885
(4) Please specify all other paediatric CT
examinations frequently performed in your institution
(comprising more than 5% of all paediatric CT
examinations)
(3) Total number of paediatric CT examinations per
year for children up to 12 years
(approximate value or average of previous year))
(2) Total number of CT examinations per year
(approximate value or average of previous year))
(1) Please specify a contact person for queries
(mandatory)!
Remarks
XVI
Others: (3)
NNH
Spine
Entire abdomen
Chest
Brain
Type of examination
Others: (3)
NNH
Spine
Entire abdomen
Chest
Brain
Type of examination
Others: (3)
Facial bone / sinuses
Spine
Entire abdomen
Chest
Brain
Type of examination
(3)
(4)
Mode
[Seq/Spi]
[cm]
(4)
Appr. length
(3)
Mode
[Seq/Spi]
[cm]
(4)
Appr. length
(3)
Appr. length Mode
[cm]
[Seq/Spi]
[kV]
U
[kV]
U
U
[kV]
0
I or Q
I or Q
(5)
[mA/mAs]
(5)
[mA/mAs]
(5)
I or Q
[mA/mAs]
CT scanner
[Notation]
ADC
[Notation]
ADC
ADC
[Notation]
Manufacturer
(5)
(5)
(5)
(6)
[s]
tR
(6)
[s]
tR
(6)
tR
[s]
N
N
N
(7)
(7)
(7)
(8)
[mm]
hcol
(8)
[mm]
hcol
(8)
hcol
[mm]
(9)
[mm]
TV
(9)
[mm]
TV
(9)
TV
[mm]
Scanner type
(9)
Pitch
(9)
Pitch
(9)
Pitch
(10)
[mm]
hrec
(10)
[mm]
hrec
(10)
hrec
[mm]
(10)
[mm]
RI
(10)
[mm]
RI
(10)
RI
[mm]
(11)
Filter
Recon.-
(11)
Filter
Recon.-
(11)
Recon.Filter
(12)
C/W
(12)
Window
C/W
Window
(12)
Window
C/W
Year:
Set-up
Month:
Fig. A2a Page 1 of the questionnaire for the registration of scan protocols and examination frequencies in phase II of the survey (translated).
2 to 5 years
Age group
Up to 1 year
Age group
Newborn
Age group
Contact person for queries?
Tel. or e-mail (1)
Institution
[mGy]
CTDIvol
[mGy*cm]
DLP
CTDIvol
(13) [mGy]
series
DLP
[mGy*cm]
No. of Dose displayed (14)
(13)
series
No. of Dose displayed (14)
No. of Dose displayed (14)
series CTDIvol
DLP
(13) [mGy]
[mGy*cm]
(2)
[%] (2)
fraction
Appr.
[%] (2)
fraction
Appr.
Appr.
fraction
[%] (2)
Exams per year
XVII
Page 1
Others: (3)
NNH
Spine
Entire abdomen
Chest
Brain
Type of examination
Others: (3)
Facial bone / sinuses
Spine
Entire abdomen
Chest
Brain
Type of examination
(4)
[cm]
(3)
Mode
[Seq/Spi]
Appr. length
(4)
[cm]
(3)
Mode
[Seq/Spi]
Appr. length
U
[kV]
U
[kV]
0
I or Q
I or Q
(5)
[mA/mAs]
(5)
[mA/mAs]
ADC
[Notation]
ADC
[Notation]
(5)
(5)
tR
(6)
[s]
tR
(6)
[s]
N
N
(7)
(7)
hcol
(8)
[mm]
hcol
(8)
[mm]
TV
(9)
[mm]
TV
(9)
[mm]
(9)
Pitch
(9)
Pitch
(10)
[mm]
hrec
(10)
[mm]
hrec
(10)
[mm]
RI
(10)
[mm]
RI
Page 2
(11)
Filter
Recon.-
(11)
Filter
Recon.(12)
C/W
(12)
Window
C/W
Window
Fig. A2b Page 2 of the questionnaire for the registration of scan protocols and examination frequencies in phase II of the survey (translated).
11 to 15 years
Age group
6 to 10 years
Age group
Institution
DLP
[mGy*cm]
(13)
series
[mGy]
CTDIvol
[mGy*cm]
DLP
No. of Dose displayed (14)
CTDIvol
(13) [mGy]
series
No. of Dose displayed (14)
Appr.
[%] (2)
fraction
Appr.
fraction
[%] (2)
XVIII
Page 2
___________________________________________________________________________ XIX
Instructions for Use of the Questionnaire ’Paediatric CT’
General remarks:
-
Please fill in separate questionnaires for each scanner if you should operate
more than one scanner.
-
Please specify data to the category ’Others’ only for those types of examinations that comprise at least 10 % of all paediatric CT examinations performed at your
institution.
Typical anatomical landmarks of scan ranges:
Region
Brain
Chest
Entire abdomen
Upper limit
Vertex
C7/T1
Diaphragm
Lower limit
Scull base
Sinus
Pubic symphysis
In order to ensure a high quality of the submitted data and to minimize the number of queries
we kindly ask you to carefully read the following explanations and to observe them when filling in the questionnaires.
1) Please specify a contact person to whom queries can be addressed.
2) Please make reliable specifications of the number of paediatric CT examinations per year
(example: 350) and of the percentage fraction of the corresponding types of examination
and age groups (referring to the total number of all paediatric CT examinations).
3) In field ’Appr. length’ the approximate typical length of the scan range (not that of the
scan projection radiograph (topogram etc.)) in [cm] must be stated. Below ’Others’ only
those examinations that comprise at least 10% of all paediatric CT examinations should be
taken into account. Please specify separately for each type of examination and age group.
Example: 17 (cm).
4) Please specify in field ‘Mode’ whether the examination is carried out in sequential (’Seq.’)
or in spiral scanning mode (’Spi.’). Example: Spi.
5) In field ’I or Q [mA/mAs]’ please take care
a) that either tube current (mA) or tube current-time product values are stated as displayed on your scanner. Example: 125 (mAs).
b) The conversion from mA to mAs and to electrical or effective mAs will be mode by us.
c) If your scanner is equipped with an automatic dose control device (e.g. ‘DoseRight‘ etc.),
the dose-saving feature applied by you should be specified in the field ’ADC [notation]’.
Example: DoseRight DOM.
d) Warning: When using ADC devices, typical mA or mAs values must be stated that
result on average for the pertaining age group and type of examination!
Fig. A3a Instructions for use of the questionnaire in phase II of the survey (p.1, translated)
FILENAME
1
XX ____________________________________________________________________________
6) Field ’tR’ requires the applied rotation time, not the total can time. Example: 0,75s.
7) Please specify in field ’N’ the number of slices that are simultaneously acquired per
rotation. Example: 16.
8) For the slice collimation ’hcol’ the thickness of the smallest single collimation used for
scanning must be entered (e.g. 2.5 mm for a scan made with a 4 x 2.5 mm beam width). Example: 2,5 (mm).
9) Please enter to fields ’TF’ or ’Pitch’ – depending on which parameter is displayed at the
scanner’s console – either the table feed (or increment) in [mm] per rotation (not the table
speed (in [mm/sec])) or the pitch factor. Example: 7 (mm) or 1.5.
10) Please specify in field ’hrec’ the thickness of the slices that are reconstructed from the
acquired data (i.e. whether data acquired with a beam width setting of 4 x 1.25 mm are used
as 1.25 mm thick slices or are reconstructed as 2.5 mm thick slices). Reconstruction increment (field ’RI’) denotes the spacing between the reconstructed slices (which can be
smaller than the slice thickness). Example: 5 (mm) and 2.5 (mm).
11) Field ’Recon.-Filter’ requires the notation of the reconstruction filter (= reconstruction
algorithm, filter kernel etc.) that is used for image reconstruction from the raw data. Example: AH40.
12) Please specify in field ’Window’ the settings for window centre (C) and window width
(W) that are routinely used for diagnosis. Example: 40/100.
13) The number of ’Series’ refers to the number of times a scan region (or a part of it) is
scanned more than once (e.g. liver without and with administration of contrast = 2 series). An
examination that is performed in several consecutive steps (e.g. entire trunk = chest + upper
abdomen + pelvis) is counted as 1 series only. A series that covers only a portion of the scan
region contributes a fraction only (e.g. entire abdomen with 1st series = entire abdomen, 2nd
series = upper abdomen results in a total of 1.5 series).
14) All modern scanners should be equipped with a dose display (indicating at least volume
CTDI (CTDIvol = weighted CTDI / pitch), occasionally also dose-length product (DLP)). Please
specify in field ’Dose display’ the values indicated at your scanner in terms of the units required in the questionnaire for a complete scan series. Example: 10.5 (mGy) und 211
(mGy*cm).
Please don’t hesitate to contact either Dr. Stamm (phone: 0511/532-2690) or Dr. Nagel
(phone: 040/ 5078-2742) if there should be any questions left.
Fig. A3b Instructions for use of the questionnaire in phase II of the survey (p. 2, translated)
FILENAME
1
Qeff
CCC
DDD
BRN5
FBS5
CHE5
ABD5
LSP5
BRN10
FBS10
CHE10
ABD10
LSP10
BRN15
FBS15
CHE15
ABD15
LSP15
Relative values (in %) refer to the reference values for the corresponding type of examination, age group and dose quantity as proposed by us;
the labels "16" und "32" added to CTDIvol and DLP specify the diameter (in cm) of the underlying dosimetry phantom.
Brain
Fac. Bone/Sin.
Chest
ent. Abdomen
Lumbar Spine
Brain
Fac. Bone/Sin.
Chest
ent. Abdomen
Lumbar Spine
Brain
Fac. Bone/Sin.
Chest
ent. Abdomen
Lumbar Spine
Remarks:
120
55
60
330
80
38
50
280
50
23
40
210
4
16
16
16
4
16
16
16
4
16
16
16
1.5
1.5
0.8
4.5
1.5
1.5
0.8
4.5
1.5
1.5
0.8
4.5
1.5
1.0
0.9
0.8
1.0
1.0
0.9
0.8
1.0
1.0
0.9
0.8
1.0
1.0
2.0
1.0
1.0
4.5
2.0
1.0
1.0
4.5
2.0
1.0
1.0
4.5
2.0
1.0
30.0
21.0
9.0
14.4
27.0
19.0
7.6
12.6
21.0
14.0
6.0
10.8
20.0
12.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
n.a.
n.a.
8.7
44.5
10.4
4.9
7.2
37.7
6.5
3.0
5.8
28.3
4.6
2.2
4.3
18.9
n.a.
n.a.
94
661
322
113
68
493
162
53
45
319
109
36
23
178
8.0
3.7
n.a.
n.a.
5.4
2.5
n.a.
n.a.
3.4
1.5
n.a.
n.a.
2.3
1.1
n.a.
n.a.
273
91
n.a.
n.a.
166
58
n.a.
n.a.
84
27
n.a.
n.a.
56
19
n.a.
n.a.
42
4.4
1.4
0.3
1.8
4.6
1.5
0.2
1.6
3.3
1.0
0.2
1.3
3.1
0.9
0.2
1.2
3.8
E (m.)
6.4
1.8
0.3
2.0
6.6
1.9
0.2
1.8
4.8
1.3
0.2
1.4
4.5
1.2
0.2
1.4
5.4
1.5
n.a.
n.a.
94
661
322
113
68
493
162
53
45
319
109
36
23
178
82
31
273
91
n.a.
n.a.
166
58
n.a.
n.a.
84
27
n.a.
n.a.
56
19
n.a.
n.a.
42
16
n.a.
n.a.
4.4
1.4
0.3
1.8
4.6
1.5
0.2
1.6
3.3
1.0
0.2
1.3
3.1
0.9
0.2
1.2
3.8
1.2
0.2
1.7
6.4
1.8
0.3
2.0
6.6
1.9
0.2
1.8
4.8
1.3
0.2
1.4
4.5
1.2
0.2
1.4
5.4
1.5
0.2
1.8
[mSv]
E (f.)
E
80%
54%
43%
74%
80%
58%
42%
75%
81%
54%
44%
71%
91%
63%
39%
57%
152%
111%
48%
70%
55%
45%
41%
72%
68%
54%
38%
69%
64%
48%
36%
61%
75%
65%
24%
46%
148%
126%
30%
62%
57%
46%
41%
69%
58%
55%
39%
70%
85%
49%
35%
62%
112%
73%
24%
47%
188%
142%
31%
63%
[mGy] [mGy*cm] [mSv]
DLP
Relative Values
CTDIvol
Fig. A4 Example of feedback given to a participant in the survey, comprising examination parameters, and absolute and relative dose values (for terms and abbreviations see tab. A7).
120
120
120
120
120
120
120
120
120
120
120
120
16
1.2
3.5
9.0
2.3
1.2
21
178
LSP1
35
1.5
1.0
4.5
82
16
0.2
1.8
Lumbar Spine
120
16
0.8
1.0
4.6
1.1
0.2
1.7
ABD1
17
0.8
4.5
1.0
31
n.a.
n.a.
ent. Abdomen
120
4
16
14.0
2.2
n.a.
n.a.
CHE1
30
140
2.0
1.0
21
178
Chest
120
120
1.0
10.0
4.3
18.9
FBS1
1.5
1.0
1.0
1.0
BRN1
16
1.2
3.0
9.0
Fac. Bone/Sin.
35
1.5
1.0
4.5
Brain
120
16
0.8
LSP0
17
0.8
DLP32
[mSv] [mGy*cm] [mGy*cm] [mSv]
ABD0
1.0
[mGy*cm] [mSv]
9000
149
Dose Values per Examination
DLP16
Lumbar Spine
120
16
4.5
[mGy]
E (f.)
ent. Abdomen
4
[mGy*cm]
E (m.)
CHE0
30
140
[mGy]
DLP32
Exams p.a. tot.:
Exams p.a. paed.:
Chest
120
120
(Phases)
CTDIvol32
Dose Values per Scan Series
DLP16
Y
OCC
FBS0
[cm]
CTDIvol16
Dose Display:
ADC:
BRN0
[mm]
Series
2002
12
Fac. Bone/Sin.
[mm]
L
Inst. Year
Month:
Brain
[kV] [mAs]
hcol Pitch hrec
N
U
Manufact.:
Type:
Examination Parameters
Type of Examination
AAA
BBB
Age
11 to 15 years
6 to 10 years
2 to 5 years
Up to 1 year
Newborn
group
Institution:
City:
German Survey on Paediatric CT 2005/2006
XXI
0%
20%
40%
60%
80%
100%
120%
140%
BRN10
LSP5
ABD5
CHE5
FBS5
BRN5
Type of examination / age group
LSP15
ABD15
CHE15
FBS15
BRN15
LSP10
ABD10
CHE10
FBS10
LSP1
ABD1
CHE1
FBS1
BRN1
LSP0
ABD0
CHE0
FBS0
BRN0
Fig. A5 Relative dose values in terms of volume CTDI (CTDIvol) and dose-length product examination (DLP) for the example presented in fig. A4. For each type of
examination and age group, the100% level refers to the corresponding reference values for paediatric CT examinations proposed by us.
Relative dose
160%
CTDIvol
DLP
XXII
LSP0
LSP0
ABD15
ABD15
ABD10
ABD10
Type of examination / age group
Type of examination / age group
(c)
act.
ref.
(a)
Pitch factor
Reconstructed slice thickness [mm]
LSP5
LSP1
LSP1
BRN15
BRN15
BRN5
BRN10
BRN10
BRN1
BRN1
BRN0
BRN0
0
1
2
3
4
5
6
7
0
0.2
Type of examination / age group
Type of examination / age group
(d)
act.
ref.
(b)
act.
ref.
Fig. A6 Comparison of the parameters applied by the particular participant from fig. A4 and the corresponding average values from the survey for scan length (a), pitch factor
(b), number of scan series (c) and reconstructed slice thickness (d). If necessary, these data can help to identify the origin of above-average dose values.
0
0.5
1
1.5
2
0
LSP5
LSP10
LSP10
5
LSP15
LSP15
0.4
BRN0
BRN0
10
BRN1
BRN1
0.6
BRN5
BRN5
0.8
BRN10
BRN10
1
BRN15
BRN15
Scan length [cm]
Number of scan series
act.
ref.
SIN0
SIN0
15
SIN0
SIN0
BRN5
SIN1
SIN1
SIN1
SIN1
SIN5
SIN5
SIN5
SIN5
SIN10
SIN10
SIN10
SIN10
SIN15
SIN15
SIN15
SIN15
CHE0
CHE0
CHE0
CHE0
CHE1
CHE1
CHE1
CHE1
CHE5
CHE5
20
CHE5
CHE10
CHE10
CHE5
CHE10
CHE10
CHE15
CHE15
CHE15
CHE15
ABD0
ABD0
ABD0
ABD0
ABD1
ABD1
ABD1
ABD1
ABD5
ABD5
ABD5
ABD5
ABD10
ABD10
25
ABD15
ABD15
1.2
LSP0
LSP0
30
LSP1
LSP1
1.4
LSP5
LSP5
35
LSP10
LSP10
1.6
LSP15
LSP15
40
XXIII
XXIV