Updated Australian diagnostic reference levels for adult CT

Area of Science:

• Medical Imaging
• Radiology
• Radiation Protection

Background:

• The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) updated national Diagnostic Reference Levels (DRLs) for adult computed tomography (CT) in 2018.
• The previous DRLs were established in 2012, necessitating an update to reflect current practices and augment DRL categories.

Purpose of the Study:

• To present the updated national DRLs for adult CT procedures in Australia.
• To describe the methodology used in revising and producing these updated DRLs.

Main Methods:

• Analysis of patient survey data submitted to ARPANSA's National Diagnostic Reference Level Service (NDRLS).
• Determination of dose metric quartiles categorized by procedure type.
• Engagement with a radiology professions liaison panel to review categories and recommend revised DRLs.

Main Results:

• Eight revised procedure categories were established for adult CT DRLs.
• Updated Australian national DRLs were recommended, with values ranging from 10 mGy/390 mGycm (chest) to 52 mGy/880 mGycm (head).
• The revised DRLs represent a 12–26% reduction in dose-length product and a 13–63% reduction in volume computed tomography dose index compared to previous DRLs.

Conclusions:

• Australian national DRLs for adult CT have been successfully reviewed and revised.
• The updated DRLs are lower than previous ones, better aligning with current Australian imaging practices.
• The revised Australian DRLs are comparable to those observed in other developed nations.