A guide to foetal dose minimisation in computed tomography pulmonary angiography of the pregnant patient

Abstract

AbstractPurpose: For pregnant patients the imaging choice between computed tomography pulmonary angiography (CTPA) and ventilation‐perfusion scintigraphy (VQ) in the investigation of pulmonary emboli (PE) is clouded by perceptions of radiation dose levels reaching the foetus. There is also uncertainty amongst medical professionals regarding the subsequent need to implement measures directed at reducing this dose. The aim of this article is to clarify the various theories surrounding CTPA of the pregnant patient and provide radiographers and medical professionals with a clear, concise understanding of how to reduce the radiation dose to the foetus during CTPA scanning. Methods: In a review of the current data surrounding foetal doses in relation to CTPA this paper is able to compare CTPA and VQ foetal doses. By collating information from the limited number of studies performed on foetal dose reduction techniques for CTPA a number of conclusions were drawn in order to formulate a scanning guide for radiographers. Results: Current opinion suggests that the benefits of CTPA outweigh those of VQ with respect to foetal radiation dose. Survey evidence suggests that often no foetal dose reduction strategies are implemented when scanning a pregnant woman for CTPA. Recently published studies have shown that simply by altering the CTPA scanning parameters, such as kVp, mAs, and scan length, using lead protection on the abdomen, and even ingesting barium sulphate solution the dose received by the foetus can be reduced by at least half. Conclusion: Since the stochastic effects of radiation are relatively unknown it is prudent to use any practical techniques aimed at reducing the foetal dose during a CTPA study. Since most of the measures investigated are practical and cause little patient discomfort the authors suggest that consideration should be given to integrating these modifications into current routine scanning protocols.