Radiation Control, X-ray Unit
625 North Robert Street
PO Box 64497
St. Paul, Minnesota 55164-0497
651-201-4545
www.health.state.mn.us/xray
[email protected]
SELF-REFERRAL SCREENING
2013 CT ANNUAL REPORT
Registrants approved by Minnesota Department of Health (MDH) to perform Computed
Tomography (CT) Cardiac, Lung, and/or Colon self-referral screening annually provide the
following data within this report. Individuals are encouraged to use this data for developing
new self-referral screening programs or reviewing current screening practices relative to
patient exposures and ALARA principles.
SELF-REFERRAL
SCREENING PROGRAM
BACKGROUND INFORMATION
ANNUALLY
REQUESTED
DATA:
● Number of CT self-referred
patients screened for each
If an individual wishes to have an examination not ordered by a
licensed practitioner of the healing arts, MDH regulates the program
designed and equipment used to detect or evaluate specific health
conditions. An application and approval from the Commissioner is
required before these examinations can be performed. The regulations
governing self-referral screening are contained in the Ionizing Radiation
Rules, Chapter 4732.
type of examination per
When a patient chooses to be screened without consulting a licensed
practitioner of the healing arts, it is particularly important to protect
individuals from unnecessary radiation exposure resulting from CT selfreferral screening examinations. The registrant must provide MDH with
nationally recognized standards or copy of site specific guidelines and
criteria the organization follows for each area performing CT selfreferral screening. MDH reviews the determinants used for selection of
patients to be screened.
examination
Every reasonable effort should be made to maintain radiation
exposures as low as is reasonably achievable (ALARA). The registrant
should consider the ALARA philosophy in the development of work
plans involving the procedure and protocol used for CT self-referral
screening examinations.
Registrants must provide assurance that the operator, patient, and
member of the public are not receiving unnecessary radiation exposure
by testing equipment at regular intervals. Equipment Performance
Evaluations (EPE) are required at intervals not to exceed 12 months
because of the complexity and higher output of these units. The only
individuals authorized to assess the performance measurements on CT
scanners performing CT self-referral screening are diagnostic
radiologic physicists.
The registrant must submit as part of the screening application, the
calculation of each screening study using the CTDI-vol output value
from each CT unit performing self-referral screening examinations. The
CTDI-vol output values are based on the factors programmed within the
scanner.
calendar year
● Number of positive results
for each type of screening
● Type of scanner used in
performing these
examinations by detector
configuration (slice)
● Average total dose length
product given to the patient in
mGy-cm for each detector
configuration (slice)
2013 ANNUAL SCREENING QUESTIONAIRE
Registrants approved by MDH to perform CT self-referral screening receive an annual questionnaire in
January to collect data regarding self-referral screenings performed the previous year. The major
components of this questionnaire include the number of CT self-referred patients screened for each
type of examination, number of positive results for each type of screening examination, type of scanner
used in performing these examinations by detector configuration (slice), actual CTDI-vol in mGy
calculated from factors programmed in CT scanner, and average total dose length product given to the
patient in mGy-cm for each detector configuration (slice).
Number of CT self-referred patients screened for each type of examination
Minnesota had a total of 42 approved screening locations in 2013. Of the 42 self-referral screening
locations; 33 were approved for Cardiac, 28 were approved for Lung, and 14 were approved for Colon.
Data collected from all approved self-referred screening locations indicated a combined total of 1,856
examinations for all screening areas.
Cardiac CT self-referred screening was identified as the predominant examination in Minnesota. Total
CT self-referral screening examinations performed in 2013 was 1,856; 1,824 of the exams were
Cardiac, 23 of the exams were Lung, and 9 of the exams were Colon. The data is represented in the
graph below.
MDH CT Self-Referral Screening
Lung
1%
Colon
1%
Cardiac
98%
Number of positive results for each type of screening examination
The annual questionnaire requests the number of examinations that were interpreted with a positive
finding for each area approved, i.e. Cardiac, Lung, and Colon. The registrant determines the extent to
which an examination is considered positive.
Data analysis of the 1,824 Cardiac self-referral
examinations indicated 985 with a positive
finding. The chart to the right is a graphical
representation of the data.
Cardiac Self-Referral
Screening
Postive
results
54%
Lung Self-Referral
Screening
Negative
results
46%
Data analysis of the 23 Lung self-referral
examinations indicated 9 with a positive finding.
The chart to the left is a graphical
representation of the data.
Positive
results Negative
39%
results
61%
Data analysis reported of the 9 Colon selfreferral examinations indicated 4 with a positive
finding. The chart to the right is a graphical
representation of the data.
Colon Self-Referral
Screening
Positive
results
44%
Negative
results
56%
Scanner, CTDI-vol (mGy), & Dose Length Product
The annual questionnaire requests the manufacturer of the primary unit performing CT self-referral
screening by detector configuration (slice). The registrant will also indicate if the primary unit uses dose
reduction software for the programmed self-referral screening protocol and/or gating capabilities.
The survey requests the average dose length product given to the patient in mGy-cm for each detector
configuration (slice). As a part of the annual application, self-referral screening applicants are required to
submit an actual CTDI-vol in mGy calculated from factors programmed in CT scanner. All data
represented below are averaged.
CARDIAC
Of 42 approved screening locations, 30 scanners actively performing Cardiac self-referral screening.
•
12 Siemen scanners – 12 use dose reduction software
- 2 Siemens 16 include gating
- 2 Siemens 64 include gating
- 4 Siemens 128 include gating
- 1 Siemens 320 include gating
•
16 GE scanners – 11 use dose reduction software
- 4 GE 16 include gating
- 2 GE 64 include gating
•
1 Philip scanner – 1 use dose reduction software and gating
•
1 Toshiba scanner – 1 use dose reduction software and gating
Cardiac Siemens CTDI-vol
8
7
6
5
4
3
2
1
0
Cardiac Siemens DLP
120
100
80
60
40
20
Siemens 16 Siemens 64
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
2.52
4.67
7.6
Siemens
128
1.2
2.9
4.6
Siemens
320
1.26
3.39
7.15
3.42
3.42
3.42
0
Siemens
16
● Min DLP
● Average DLP
● Max DLP
Siemens
64
38
66.8
106.4
Siemens
128
85.9
97.2
108.5
Siemens
320
5.81
37.37
100.35
43
43
43
Cardiac GE CTDI-vol
Cardiac GE DLP
300
25
250
20
200
15
150
10
100
5
50
0
0
GE 16
GE 16
GE 64
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
2.1
14.26
22.13
8.6
9.5
10.4
● Min DLP
● Average DLP
● Max DLP
GE 64
21.99
215.97
271
112
141.83
171.66
Cardiac Philips DLP
Cardiac Philips CTDI-vol
120
6
100
80
4
60
40
2
20
0
0
Philips 64
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
5.8
5.8
5.8
● Min DLP
● Average DLP
● Max DLP
6
120
5
100
4
80
3
60
2
40
1
20
Toshiba 160
101
101
101
Cardiac Toshiba DLP
Cardiac Toshiba CTDI-vol
0
Philips 64
0
Toshiba 160
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
7.14
7.14
7.14
● Min DLP
● Average DLP
● Max DLP
90.3
90.3
90.3
LUNG
Of 42 approved screening locations, 16 scanners actively performing Lung self-referral screening.
•
•
5 Siemen scanners – 5 use dose reduction software
11 GE scanners – 7 use dose reduction software
Lung Siemens CTDI-vol
Lung Siemens DLP
20
300
250
15
200
10
150
100
5
0
50
Siemens 16
Siemens 64
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
5.85
10.58
15.32
Siemens 128
4.79
4.79
4.79
7.42
8.16
8.91
0
Siemens 16
● Min DLP
● Average DLP
● Max DLP
Lung GE CTDI-vol
Siemens 128
158
216.88
275.76
77
77
77
247.5
247.5
247.5
Lung GE DLP
400
12
10
300
8
200
6
4
100
2
0
Siemens 64
GE 4
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
GE 8
3.4
3.75
4.17
GE 16
3.23
3.23
3.23
0
GE 64
1.87
4.46
11
2.67
3.3
3.94
GE 4
● Min DLP
● Average DLP
● Max DLP
GE 8
102
112.35
125
GE 16
113.25
113.25
113.25
GE 64
64.01
149.69
377.6
113
115.5
118
COLON
Of 42 approved screening locations, 4 scanners actively performing Colon self-referral screening.
•
•
1 Siemen scanner – 1 use dose reduction software
3 GE scanners – 2 use dose reduction software
Colon Siemens CTDI-vol
Colon Siemens DLP
10
500
8
400
6
300
4
200
2
100
0
0
Siemens 16
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
8.87
8.87
8.87
Siemens 16
● Min DLP
● Average DLP
● Max DLP
Colon GE CTDI-vol
5.6
Colon GE DLP
1000
5.4
5.2
800
5
600
4.8
400
4.6
200
4.4
4.2
478.98
478.98
478.98
0
GE 4
GE 16
GE 64
GE 4
● Min DLP
● Average DLP
● Max DLP
*The Colon DLP is reported combining both supine and prone imaging.
GE 16
768
768
768
GE 64
427.29
427.29
427.29
880
880
880