1. Diagnostic Reference Levels for Digital Mammography, time for a new paradigm
Moayyad E Suleiman
Prof. Patrick C Brennan
Dr. Peter Kench
Dr. Jennifer Diffey
Ms. Lucy Cartwright
AProf. Mark F McEntee

2. To recommend DRLs for NSW digital mammography.
Aims
To recommend DRLs for NSW digital mammography.

3. DRLs
DRL: A dose investigation level that is not to be exceeded for a standard procedure on a standard size patient when good and normal practice is applied.

4. Methods used to establish DRLs
Suleiman, M. E., Brennan, P. C., & McEntee, M. F. (2015). Diagnostic reference levels in digital mammography: a systematic review. Radiation Protection Dosimetry, 167(4), doi: /rpd/ncu365

5. DRLs
Level
MGD
Standard breast
Patient
Phantom
95th %
Dance
Thickness
Density
ACR
75th %
Boone
Average thickness
50%
EUREF
Other Wu
40-60
28%
IAEA
45-55
Dance scale
IPEM
55-65

6. DRLs
Level
MGD
Standard breast
Patient
Dance
Thickness
Density
75th %
Average thickness
20-110
With 10 mm ranges
Dance scale

7. Data
52,000
Mammograms
12,000
Women

8. Criteria Inclusion Age Breast thickness Exclusion criteria
Breast implants
Missing DICOM info
Missing QA data

9. Final data set
BreastScreen centers 48
Units 61
Mammograms
45054
Cases
11030

11. MGD distribution

12. Breast thickness distribution
110 mm
20 mm

13. Tukey’s post-hoc test showed statistically significant differences between mean image MGDs for each 10mm thickness CBT range examined

14. Breast thickness range (mm)
Proposed DRLs
Breast thickness range (mm)
All Units CR DR
Photon counting
75th %
(mGy)
95th %
20-29
0.97
1.19
1.17
1.26
1.11
0.58
0.63
30-39
1.13
1.50
1.52
1.12
1.22
0.60
0.65
40-49
1.31
1.86
1.92
2.08
1.30
1.41
50-59
1.67
2.38
2.48
2.58
1.65
1.80
0.69
60-69
2.37
3.00
3.08
3.21
2.35
2.57
0.88
0.99
70-79
2.23
4.38
4.41
4.46
2.67
1.08
1.56
80-89
6.24
6.39
6.74
2.34
3.07
90-99
2.89
7.75
7.84
7.85
2.63
3.48
1.39
3.24
5.97
6.26
3.31
5.38
0.91
0.92
DRLs
60±5
2.06
2.22
2.04
0.79
CR: Computed Radiography, DR: Digital Radiography

15. In perspective DR 95th for UK 2016 1.46 Oblique, 1.32 CC
Vs 1.83 for us CR

16. DRLs are supposed to be simple, why complicate it?
International comparisons.
All MGDs are estimates
Mean Glandular dose uses an assumption if 50/50 density/fat
Technology makes it easier to establish DRLs.
Dose audits are used to estimate risk from exposure to x-ray.
DRLs should use the dose closest to the truth

17. Currently: Use LIBRA to find Mammographic Breast Density and calculate the Actual Glandular Dose
Original
Segmentation
Density
Intensity histogram
Breast area
Dense area
Density 10%

18. Thank you