Room: AAPM ePoster Library
Purpose: purpose of this study is to evaluate the feasibility of a mathematical model based on PSRAD model for organ dose estimation in CT examinations using anthropomorphic phantoms.
Methods: Planar Scan Range Average Dose model estimates the organ doses for scan length of 30 cm, and different patient sizes. First of all the accuracy of the model for scan lengths of 30 to 54 cm was verified. Second, the 10 male and female adult phantoms in Virtual Dose software were used for obtaining the real dose of fully-irradiated organs in body CT examinations with the same scan lengths. The real organ doses were compared to those obtained by the PSRAD model. The correction factors, CForgan, which is the ratio of real organ dose to PSRAD model, were then obtained and analyzed. Finally, the PSRAD model was modified by applying a correction factor - based equation to estimate the organ dose more accurately.
Results: results show that the underestimation of the model in dose prediction was less than 4% for scan lengths other than 30 cm. The correction factor, CForgan, was found to have an increasing trend with scan length, and differed in different organs. The differences between real organ doses and those obtained from PSRAD and modified models were found to be between 20 to 68% and 8 to 12% respectively. These differences decreased for higher scan lengths.
Conclusion: results shows the feasibility of the mathematical model for organ dose estimation in CT scan. The accuracy of the model depends on the organ type and scan length.