Fetal radiation dose for pregnant patients undergoing CTPA examinations: comparative calculations in a case series with two Monte Carlo-based software products

BACKGROUND: Pregnancy constitutes a common risk factor for maternal pulmonary embolism (PE). This study determines the fetal dose, maternal effective dose (ED), and organs’ doses (ODs) for computed tomography pulmonary angiography (CTPA) examinations.METHODS: Patient and dosimetric data, exposure and technical parameters from CTPAs in six pregnant women with suspected PE were inserted into Conceptus Dose Estimation (CODE) and VirtualDoseCT Monte Carlo-based software to calculate the fetal doses and ODs. The maternal ED was calculated by multiplying the dose length product with an appropriate conversion coefficient.RESULTS: Fetal doses ranged from 0.10 to 0.33 mGy for CODE with over-ranging and 0.06 to 0.18 mGy and 0.08 to 0.25 mGy for VirtualDoseCT without and with over-ranging, respectively. The gestational age and scanning length were the main factors affecting the fetal absorbed doses. Patient EDs ranged from 1.4 to 2.1 mSv, while the highest mean ODs received by the maternal breast (8.41 mGy), lung (6.29 mGy), heart (6.25 mGy), and thymus (5.76 mGy), all inside the scanning range. This study’s results are comparable to or lower than most of the literature’s corresponding values. CONCLUSIONS: From a radiation protection perspective, presumed that adequate justification for the necessity of the examination is provided by the referring physician, patient-tailored CTPAs are considered a safe imaging method for pregnant women with suspected PE.