Research And Development Of Pencil Beam Dose Calculation System Based On Monto Carlo For IMRT

More than 70% cancer patients need radiation therapy, and Intensity Modulated Radiation Therapy(IMRT) is the most effective means in radiation therapy. Dose calculation Method is the key of designing radiation therapy plans system, and the accuracy and rapidity of the calculation direct directly affects the efficacy and efficiency of the treatment delivery. In order to break the monopoly of European-American countries on the high-end radiotherapy system and improve the level of domestic radiotherapy equipment, we have done a series of studies on dose calculation of IMRT planning system as follows:l)Research on Monto Carlo simulation of radiation therapy base on Gate. We have built Gate simulation platform for Radiation therapy in linux systems, and simulated Elekta Precise series medical linear accelerator for 6MV photon IMRT. We have conducted the radiation therapy simulation studies of HNC, and built the 6MV photon source phase space model by simulating the accelerator head. We have obtained the dose deposit kernel which including spectrum information for Pencil Beam algorithm based on Monto Carlo by fitting the experimental result of irradiating water tank using Gate platform to the dose deposit.2) Research on Monto Carlo based Pencil Beam Algorithm. The irregular radiation field was divided into numbers of finite-size pencil beams, and the beams is convoluted with the dose deposit kernel, then we obtain the 3D dose distribution of the patient. This method is point oriented and thus faster than a full 3-D convolution algorithm. For heterogeneous media, a radiation depth is derived along the ray path. We have compared calculation result with clinical dose data, and demonstrated that this method may meet the requirements of an 3-D treatment planning system.3) Research on dose calculation software for IMRT. We have designed and developed dose calculation software, IMDC, based on Monto Carlo Pencil Beam, and integrated into the software, MBIG-IRT. The main function that we have developed in this study include:?Open and Close radiotherapy files, browse and display patient radiotherapy planning information and image information;?Dose calculation for IMRT and saved the resulting dose as a DICOM RD file;?Assess visually the results by DVH evaluation and isodose.