Fetal organ dose assessment during pelvic CT examination using Monte Carlo/GATE simulation and pregnancy voxelized phantom Katja

In certain situations where there is a risk of fetal-pelvis disproportion (risk that the baby will not be able to pass through the pelvis), pelvic scan examination may be prescribed to the mother at the end of pregnancy. This examination assesses the dimensions of the pelvis by measuring various bone diameters. It also provides details information about pelvis morphology. Patients are routinely worried about the risk of unwanted effects on the fetus from radiation exposure. Accepting the possibility of adverse effects from fetal exposure and the inability to measure directly in vivo [1]. Medical physicists have developed several techniques to determine the amount of radiation that reaches the fetus. Physicians need to understand these methods and how the numbers they produce relate to possible biological effects on the fetus. In this study A 16 helical multi-slice CT scanner was simulated. Full technical specifications were obtained from the constructor and simulated in GATE to produce single x-ray beams. Katja voxelized patient phantom, pregnant in 24 weeks, was scanned with pelvis protocol. The code was used to estimate the absorbed and effective doses in the important organs of the fetus as a consequence of the scanning parameters. The purpose of this study was to use patient voxelized phantom Katja to assessed fetal organ dose, effective dose and evaluate the risk related to radiation due to pelvis CT examination using Monte Carlo/Gate platform. Fetal effective doses were 4.8, 6.3 and 8.2 mSv for 80, 110 and 130 kV respectively. Fetal dose in heart, eye lens, brain was 1.61, 1.6 and 0.8 mGy for 80 kV. Since the dose to the fetus from a pelvic scan is lower than 50 mGy, when exposed to a single scan teratogenic effects on the fetus are not significant concern [2]