51 Estimation of the organ and effective dose during CT chest examination: A Monte Carlo study

Abstract

Introduction Computed tomography represents actually the most important key in medical imaging. It helps practitioner to give good diagnostic. For this reason a high quality image with low dose must be provided during CT examinations. Many methods were used to estimate organ and effective dose. In this work we aimed to estimate the organ and effective dose during chest CT examinations using the Monte Carlo code GATE (Geant4 Application for Tomographic Emission) and voxelized phantoms. Methods Two methods were used to estimate the effective dose. The first one was the conversion factors method based on the dose length product (DLP) and the conversion factor from AAPM report N°96. The second one based on the organ dose from Monte Carlo simulation and tissue weighting factors from ICRP 103 report. A CT Siemens Somatom Emotion 16 slices was modeled using GATE, a voxelized phantom ZUBAL was used in this study. Results Organ doses during CT chest examination were 0.62 mGy, 0.21 mGy, 0.76 mGy, and 0.11 mGy, 0.61 mGy for heart, lung, arm bone, trunk tissue, and ribs respectively. The effective doses were 1.85 mSv for conversion factor method and 1.17 mSv for the other method. Conclusion The Monte Carlo method with voxelized phantoms can be a good way to estimate the organ dose and the effective dose precisely.