Monte Carlo simulation for assessment of occupational doses in pediatric cardiology procedures

Abstract

In this study, we evaluated the occupational doses during a pediatric cardiac interventional radiology procedure using Monte Carlo simulations. For this purpose, we employed virtual anthropomorphic phantoms, with 1-, 5- and 10-year-old, as well as two adult phantoms to represent the medical staff. Each scenario was composed of two phantoms, the physician and the patient, coupled with the MCNPX 2.7.0 Monte Carlo code. The exposures were evaluated for six projections and beam setups, normally employed in angiographic procedures, with tube voltages of 80, 100 and 120 kVp. The conversion coefficient (CC) values for radiation protection quantities were obtained to estimate the occupational exposure. These CC values were determined as the ratio between of the equivalent or effective dose to the dose-area product. The physician’s organs with the highest effective dose contributions were the breast (female), brain, thyroid, lungs, stomach and bone marrow. The lead apron may reduce the doses by up to 100%, and the use of face protection may reduce the eye lens equivalent dose by up to 89%. The brain equivalent dose can also be reduced by 16% with the use of a lead cap. The CC values were also influenced by the patient size, beam projection angle, and acquisition parameters. The dose distributions inside the room are also depicted in a 3D map, enabling the staff to choose safer positions without compromising the procedures.