The most common imaging examinations for diagnosing pulmonary embolism are CTPA and VQ. However, a previous lack of high-quality data and analysis made it challenging to provide an accurate comparison of maternal and foetal risk of radiation-induced cancer between each imaging technique.

 

To estimate the cancer risk from maternal and foetal radiation doses associated with CTPA or VQ examinations.

 Methods

Dosimetric data was determined for 274 pregnant patients who received CTPA and/or VQ examinations at CHS between 2015 and 2022. The maternal incident and mortality radiation risks were estimated using models provided by the Biologic Effects of Ionizing Radiation (BEIR) VII report. The BEIR models account for age at exposure, time following exposure, and organ dose. Input data included median and quartile values of determined critical organ dose estimates and patient age. Risk to the foetus was determined using standard methods.

 Results

Estimated total maternal cancer incidence was 27 and 26 cases per 100,000 persons for CTPA and VQ examinations respectively, with mortality estimates of 11 and 15 deaths respectively. Cancer incidence was evenly divided between lung and breast cancer for CTPA with 80% of cancer cases for VQ being in the lung. The median foetal doses were 0.03 mSv for CTPA, and 0.29 mSv for VQ, yielding 0.5 cases of radiation-induced childhood cancers from CTPA and 4.4 cases per 100,000 persons for VQ.
 
 

Maternal cancer incidence is remarkably similar for each examination.
 
 

Knowledge of the potential long-term risks following radiation exposure from diagnostic imaging procedures is essential in the practices of justification and optimisation.

Donald McLean1, Olivia Delfino1, Marie Vozzo1
 
 

1.     Medical Physics and Radiation Engineering, Canberra Health Services, Garran, ACT, 2605