Comparison of AAPM TG282 and Dance breast dosimetry models: Impact on estimates of average MGD for the United Kingdom breast screening programmes.

Abstract

Background: The American Association of Physicists in Medicine (AAPM) Task group 282 (TG282) in collaboration with the European Federation for Organisations of Medical Physics (EFOMP) have developed a novel breast dosimetry model intended as a single international standard.

Purpose: To explore the impact of TG282 dosimetry on estimates of average Mean Glandular Dose (MGD) in the United Kingdom (UK) National Health Service (NHS) Breast Screening Programmes (BSP).

Methods: MGDs were estimated, using the TG282 dosimetry model, for the most recent UK NHSBSP dose survey. This dataset included MGDs estimated using the Dance dosimetry model for 439,916 Full Field Digital Mammography (FFDM) exposures of 111,132 women and 10,831 Digital Breast Tomosynthesis (DBT) exposures of 5,113 women. Direct comparisons of the two models were made and differences explored using this large-scale real world dataset.

Results: TG282 model MGDs were on average approximately 20 % and 15 % lower than Dance model values for FFDM and DBT respectively. For the UK National Diagnostic Reference Level (NDRL) breast thickness range of 50 mm to 60 mm inclusive differences were smaller at approximately 13 % and 10 % respectively. The difference between dosimetry models was shown to depend on the properties of the imaged population and X-ray equipment used. Average differences of up to 63.1 % were observed at higher CBT values for FFDM.

Conclusion: On average, the TG282 dosimetry model resulted in lower estimates for MGD in UK mammography. The differences were more pronounced for women with larger than average compressed breast thickness.