Establishing mammography diagnostic reference levels in Mexico: A step towards improving patient radiation protection

A quality assurance programme (QAP) must be implemented and monitored to ensure patient radiological safety in mammography units. A QAP should incorporate dosimetric patient quantities, including the mean glandular dose (MGD). The establishment of Diagnostic Reference Levels (DRLs) could promote the standardisation of radiological practices. In Mexico, QAP and DRLs are not widely used and their implementation status has not been reported.

In this work, 64 mammography units were evaluated in terms of QAP-dosimetric indicators implementation. From the 26,364 mammography views gathered during the study, local DRLs (LDRLs) were estimated based on MGD for craniocaudal (CC) and mediolateral oblique (MLO) views. Non-parametric tests were used to analyse the relationship between exposure parameters (kV, mAs, exposure time) and MGD, categorised by compressed breast thickness (CBT) and patient age.

Almost 25 % of mammography units were found to comply with the QAP dosimetric indicators evaluated. The calculated MGD values show a significant positive correlation between CBT and exposure parameters across all age groups. MGD values significantly differed between age groups, with lower values observed in the elderly group. The LDRLs for craniocaudal (CC), mediolateral oblique (MLO), and all mammography views were 1.92, 2.27, and 2.09 mGy, respectively. The LDRLs regarding CBT (<20-110 cm) ranged from 0.80 to 3.05 mGy for CC and from 0.88 to 3.20 mGy for MLO.

This study establishes the first mammography LDRL in Mexico. Given the limited compliance of QAP dosimetric indicators, the legal framework for monitoring radiological patient safety should be strengthened.

The study results could be used as tools to supervise, promote, and optimise the radiological safety and protection of patients during mammography.