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

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

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.

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), 608-619. doi:10.1093/rpd/ncu365

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

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

Data 52,000 Mammograms 12,000 Women

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

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

MGD distribution

Breast thickness distribution 110 mm 20 mm

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

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 1.39 100-110 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

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

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

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%

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