Eye lens dose estimations in chest computed tomography examinations using Monte Carlo simulations in a Siemens SOMATOM perspective scanner

Background:The radiation dose received by the eye lens when a chest computed tomography (CT) scan is performed, is generally not recorded in clinical practice, particularly due to the distance of this organ from the X-ray beam.Material and Methods: The absorbed dose in the eye lens was determined by Monte Carlo N-Particle version 5 (MCNP5) calculations and thermoluminescence dosimetry (TLD).Two models of the CT scanner and patient were constructed using the MCNP5 code.The first model was the Bottle Manikin Absorber (BOMAB), which includes the main structures of the eye, and the second was the computational voxelized phantom MAX06.In addition, measurements were carried out in 21 adult patients, which underwent a chest CT study in a Siemens SOMATOM Perspective scanner.Results: Average Monte Carlo values for the absorbed dose of 16.4 0.4 mGy and 1.97 0.04 mSv for the effective dose were obtained when the BOMAB model was used.Mean values of 13.3 0.3 mGy and 1.59 0.04 mSv, respectively, were obtained for the absorbed dose and effective dose for the MAX06 phantom.TLD measurements gave average values of 12.66 1.33 mGy and 1.52 0.16 mSv for absorbed dose and effective dose, respectively, in simple chest scans, and 7.60 0.63 mGy and 0.91 0.07 mSv, respectively, for simple contrast-enhanced studies.Conclusions: The results of the Monte Carlo simulations with BOMAB and voxelized phantoms in our study agree relatively well with each other.