Monte Carlo Organ Dose Calculation Based On A Voxel-based Rat Phantom For External Irradiation

Recently, with the development of the tomograph imaging technologies and the computer technologies, a new anatomic voxel model of animal could be constructed to review and evaluated the old points made with the old mathmetic or simple models. Furthermore a framework for assessing the impact of ionising radiation on non-human spacies is advised to promoting radiation protection and utilization for human. For those reasons, the new anatomical models need be developed and be applied to acquire the new data in dosimety.In this paper, a Sprague Dawley (SD) rat anatomy atlas was acquired by a cryosection imaging system for small animal study. Through manual, self-automatic and automatic segmentation methods, an anatomically realistic rat model was developed based on the segmented images data of the rat.In this study, the procedures of the development of the voxel rat model for external photon and electron dosimetry and for broad range of incident energy (0.01~102 MeV ) under idealized irradiation geometries (DV,VD,LLAT,RLAT,ISO) have been detailed. A set of organ absorbed dose and effective dose results are computed and tabulated firstly.A simulated computation workstation is built, from which any animals organ dose distribution could be got.The results show that the organ dose distributions of the rat are distinctly influenced by the anatomical characteristics, including organ volume, shape, location, and orientation, and the radiation conditions, such as the particl type, the incident energy and the irradiation directions and so on.Research proves that the method combining the accurate anatomical model with the Monte Carlo code is an effective way to study the organs dose distributions and the reasons. The resulted data fill a data gas between exposure and dose and between dose and certain categories of effect for the no-human species. The data is also capable of offering exact quantitative references to animal experiments in clinic radiation therapy, radionuclide therapy and radiation protection. The experience and data concerning dose assessment from the rat model will be able to be deducted to small mammals, contribute to building the same framework for small mammals and improve the radiation therapy and protection for human ultimately.