Congress:
EuroSafe Imaging 2020
Keywords:
Performed at one institution, Experimental, Not applicable, Trauma, Foetus, Biological effects, Radiation safety, Radiation effects, Diagnostic procedure, CT, Radioprotection / Radiation dose, Foetal imaging, Emergency, Action 7 - Radiation protection of children
Authors:
E. House, B. Tuohy, S. Cleary
DOI:
10.26044/esi2020/ESI-06848
Background/introduction
On occasion CT is required for the proper clinical management of a pregnant patient. It is internationally recognised that CT irradiation of a pregnant patient presents increased challenges when addressing the risk benefit relationship in diagnostic radiology. An accurate estimate of the radiation dose to the fetus is important when CT examination of the abdominal area is required. Knowledge of the fetal dose allows the Clinician to reach a considered mature decision on the level of risk the CT examination presents to the fetus. This paper presents the findings of work performed to measure radiation dose to a simulated ‘fetus’ during computed tomography (CT) scans of various anatomical sites in a pregnant patient. Radiation dose to the fetus during CT examinations is determined by the field of view irradiated, CT protocol used, and the gestational time that the irradiation occurred.
At University Hospital Galway the most common exam carried out on pregnant patients is CT pulmonary angiography (CTPA) which is used to diagnose or exclude pulmonary emboli. CT abdomen-pelvis scans can also frequently be performed when there is suspected appendicitis or major trauma1. In this study fetal doses arising from CT brain examinations will also be investigated to determine if results are in agreement with the published scientific literature which reports negligible doses are delivered to the fetus during such scans2.
The majority of published data on fetal dose estimations arising from diagnostic imaging practices have used either Monte Carlo simulations4 or direct measurement using thermoluminescent dosimeters5. This study presents a more practical reproducible simulation technique that replicates all three trimesters of pregnancy. Fetal doses delivered by the aforementioned CT scans will be measured using an ionisation chamber based radiation dosemeter. Ionisation chamber based dosemeters are commonly available in most Radiology departments in which there is onsite presence of medical physicists.