A Mathematical Head Phantom for Dosimetry Measurements by Monte Carlo Method

In diagnostic and therapeutic procedures, dosimetric studies are performed on the dosimetric systems in order to comply the radiation safety standards. Monte Carlo methods are used due to the high complexity and cost of patient-specific phantom construction. The high complexity of the digitized phantoms greatly increases the time and computational task of the Monte Carlo calculation. In many studies, all of the defined components and high precision of the voxelized phantom are not necessary and the study objectives could be achieved by a simple digital phantom modeling. In this study, an anatomic-based human head phantom was modeled considering the importance of the digitized phantoms for Monte Carlo dosimetry measurements.
Methods and Materials: In this study, the anthropomorphic head phantom was simulated using MCNPx (version 2.4.0). The proposed head phantom consist of the skull, brain, eyes, eye lens, facial bones, neck and skin that are modeled based on the atomic compositions and density magnitudes reported by ICRU report No. 44 and the national institute of standards and technology (NIST) reports.
The visual and structural characteristics of the modeled head phantom in different cross-sectional views were evaluated by two scientific experts. For modeled phantom, integrity and compliance of the structural features with the actual human head were confirmed by the experts.Simulated phantom is flexible and upgradeable. According to study objectives, other tissues including tumors, the specific tissue of interest, and etc. could be added to the model.
Discussion and Pre-clinical dosimetric studies including the determination of dose to organ at risks in the diagnostic and therapeutic situations as well as the effect of shielding methods and imaging geometries in the image quality could be evaluated using the modeled phantom.