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
2014 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 selfreferral 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 self-referral
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 CTDIvol 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)
2014 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 44 approved screening locations in 2014. Of the 44 self-referral screening
locations; 34 were approved for Cardiac, 29 were approved for Lung, and 7 were approved for Colon.
Data collected from all approved self-referred screening locations indicated a combined total of 3,215
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 2014 was 3,215; 2,892 of the exams were
Cardiac, 310 of the exams were Lung, and 13 of the exams were Colon. The data is represented in the
graph below.
MDH CT Self-Referral Screening
Lung
10%
Colon
0%
Cardiac
90%
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 2,892 Cardiac self-referral
examinations indicated 1,483 with a positive
finding. The chart to the right is a graphical
representation of the data.
Cardiac Self-Referral
Screening
Postive
results
51%
Lung Self-Referral
Screening
Positive
results
39%
Negative
results
46%
Data analysis of the 310 Lung self-referral
examinations indicated 121 with a positive
finding. The chart to the left is a graphical
representation of the data.
Negative
results
61%
Data analysis reported of the 13 Colon selfreferral examinations indicated 6 with a positive
finding. The chart to the right is a graphical
representation of the data.
Colon Self-Referral
Screening
Positive
results
46%
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 44 approved screening locations, 30 scanners actively performing Cardiac self-referral screening.
• 13 Siemen scanners – 12 use dose reduction software
- 3 Siemens 16 include gating
- 4 Siemens 64 include gating
- 2 Siemens 128 include gating
- 1 Siemens 256 include gating
- 1 Siemens 320 include gating
• 14 GE scanners – 11 use dose reduction software
- 2 GE 16 include gating
- 1 GE 64 include gating
• 2 Philip scanners – 1 use dose reduction software and gating
• 1 Toshiba scanner – 1 use dose reduction software and gating
Cardiac Siemens CTDI-vol
9
8
7
6
5
4
3
2
1
0
Cardiac Siemens DLP
140
120
100
80
60
40
20
Siemens Siemens Siemens Siemens Siemens
16
64
128
256
320
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
3.91
6.48
8.33
5.3
6.51
8.11
1.02
1.82
2.16
1.54
1.54
1.54
3.42
3.42
3.42
0
Siemens Siemens Siemens Siemens Siemens
16
64
128
256
320
● Min DLP
● Average DLP
● Max DLP
56
100.33
135
94.38
107.16
124
21
65.22
100
28.52
28.52
28.52
43
58.5
74
Cardiac GE CTDI-vol
25
20
15
10
5
0
GE 16
GE 64
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
2.14
12.51
21.17
Cardiac GE DLP
450
400
350
300
250
200
150
100
50
0
8.99
8.99
8.99
25.64
213.21
402.24
143.77
143.77
143.77
Cardiac Philips DLP
120
8
115
6
110
105
4
100
2
95
90
Philips 64
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
5.8
6.58
7.37
Toshiba 320
Philips 64
● Min DLP
● Average DLP
● Max DLP
101
108.66
116.33
Cardiac Toshiba DLP
Cardiac Toshiba CTDI-vol
7
6
5
4
3
2
1
0
GE 64
● Min DLP
● Average DLP
● Max DLP
Cardiac Philips CTDI-vol
0
GE 16
80
70
60
50
40
30
20
10
0
Toshiba 320
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
6.2
6.2
6.2
● Min DLP
● Average DLP
● Max DLP
74
74
74
LUNG
Of 44 approved screening locations, 18 scanners actively performing Lung self-referral screening.
•
•
•
4 Siemen scanners – 4 use dose reduction software
13 GE scanners – 11 use dose reduction software
1 Philip scanner
Lung Siemens CTDI-vol
8
7
6
5
4
3
2
1
0
Lung Siemens DLP
250
200
150
100
50
Siemens 16
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
0
Siemens 128
4.18
5.2
6.23
7.42
7.42
7.42
Siemens 16
● Min DLP
● Average DLP
● Max DLP
Lung GE CTDI-vol
250
4
200
3
150
2
100
1
50
0
0
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
GE 8
3.4
3.95
4.2
GE 16
2.48
2.48
2.48
GE 64
1.77
2.59
4.98
145
158.5
172
247.5
247.5
247.5
Lung GE DLP
5
GE 4
Siemens 128
2.8
3.24
3.68
GE 4
● Min DLP
● Average DLP
● Max DLP
GE 8
142
147
152
GE 16
86
86
86
GE 64
61.68
104.48
249.15
84
106.5
129
Lung Philips CTDI-vol
140
120
100
80
60
40
20
0
3
2.5
2
1.5
1
0.5
0
Lung Philips DLP
Philips 256
Philips 256
COLON
Of 44 approved screening locations, 4 scanners actively performing Colon self-referral screening.
•
•
•
1 Siemen scanner
2 GE scanners
1 Toshiba scanner – 1 use dose reduction software
Colon Siemens CTDI-vol
8
7
6
5
4
3
2
1
0
Colon Siemens DLP
600
500
400
300
200
100
0
Siemens 16
● Min CTDI-vol
● Average CTDI-vol
● Max CTDI-vol
7.48
7.48
7.48
Siemens 16
Colon GE CTDI-vol
10
8
6
4
2
0
GE 4
GE 16
Colon GE DLP
1000
980
960
940
920
900
880
860
840
Colon Toshiba CTDI-vol
7
6
5
4
3
2
1
0
GE 4
GE 16
Colon Toshiba DLP
600
500
400
300
200
100
Toshiba 320
0
*The Colon DLP is reported combining both supine and prone imaging.
Toshiba 320