26 June 2025
Researchers have developed Australia’s first set of local diagnostic reference levels (LDRLs) for digital breast tomosynthesis (DBT) based on human data, from more than 9,000 mammographic images. The research team say they intend these LDRLs to be used as a guide for monitoring radiation delivery levels, and as a quality assurance tool to assist in monitoring the performance of the mammography unit.
Published this week in the Journal of Medical Radiation Sciences (JMRS), the research offers a starting point for the development of future nation-wide diagnostic reference levels for DBT.
Australia has official diagnostic reference levels for CT scans, nuclear medicine, PET scans, and coronary angiography, but none, as yet, for mammography.
While breast cancer screening services predominantly use full-field digital mammography, DBT is the standard scan for people who have a high risk of breast cancer or are experiencing breast cancer symptoms. DBT takes multiple projections as the X-ray tube moves in an arc over the breast. This arc of projections enables the breast structures to be separated along the vertical axis for better tissue visualisation and creates a limited pseudo 3D breast image.
Mammographer and ASMIRT Board Director, Bianca Magill, regularly performs DBT scans on patients.
“We know breast tissue is particularly radiosensitive. Tracking the radiation dose patients receive during DBT scans is really important for quality assurance and patient safety,” Bianca says.
“This research represents the first step towards diagnostic reference levels. More studies contributing further data and analysis will lead to important standards in Australian mammography.”
Analysing the 9,000+ anonymised images, the research team found that variation in radiation dose was closely linked to how thick each patient’s breast was when compressed. Accordingly, their radiation dose benchmarks represent four different compressed breast thickness (CBT) measurements, shown in the table below.
| Compressed breast thickness | Radiation dose |
| 13-49mm | 1.5mGy |
| 50-74mm | 2.70mGy |
| 75-99mm | 3.90mGy |
| 100-118mm | 4.70mGy |
The researchers found significant differences between the LDRLs for each of the CBTs. This means setting a single LDRL for all CBTs may result in missing unacceptably high or low breast doses.
The study was undertaken by Michelle Kostidis, Peter Barnes, Julie Nguyen and Molly O’Donohue and is available in the JMRS.
Simone Costa
simone.costa@asmirt.org
0421 046 102
