A multicentre study to compare previous and new breast dosimetry for Digital Mammography, Digital Breast Tomosynthesis and Contrast Enhanced Mammography

Abstract

Purpose

The most widely used method in Europe to estimate breast dosimetry in mammography is based on Dance’s publications. Recently, AAPM and EFOMP joint Task Group 282 (TG282) has published a new breast dosimetry model, which improves the accuracy in Average Glandular Dose (AGD) estimation. This multicentre study aims to evaluate variations in AGD between conventional and new dosimetry across different modalities and mammography systems.

Methods

Measurements were conducted on 74 mammography systems from six vendors, installed in hospitals across Italy. Each facility used its own equipment while adhering to the same protocol and spreadsheets. Tube output and Half-Value Layer (HVL) were measured in the two configurations for Digital Mammography (DM), Digital Breast Tomosynthesis (DBT), and Contrast-Enhanced Mammography (CEM). Exposures were performed using a breast-shaped PMMA phantom of different thicknesses. Data were centrally collected to compute AGD using appropriate correction factors for conventional dosimetry and the BreastAGD282 software for TG282 dosimetry, using EU legacy model.

Results

The sample allows for the identification of typical AGD values for both methodologies. The study highlights a reduction in median AGD with the new dosimetry model compared to Dance method across all modalities and vendors. Furthermore, the reduction magnitude depends on x-ray beam quality, modality and compressed breast thickness, ranging from 6.1–8.4 % at 21 mm to 27.3–38.3 % at 90 mm.

Conclusions

The new TG282 dosimetry model showed a reduction in the estimated median AGD. Notably, the magnitude of this reduction depended on x-ray beam quality, modality and compressed breast thickness.