[Verification of the accuracy of Monte Carlo-based dose calculation algorithm, DPM, in homogeneous and inhomogeneous...

The present paper is to verify the accuracy of DPM, a Monte Carlo-based dose calculation algorithm, in homogeneous and inhomogeneous tissues. DPM was applied to calculate (1) depth dose curves and off-axis ratios at a depth of 10 cm in water using a 6 MeV photon beam with a 3 cm x 3 cm field and phase space file simulated Varian 60 degrees C medical linear accelerator with a 10 cm x 10 cm field at SSD = 100 (cm); (2) depth dose curves using 6 MeV photon beam in inhomogeneous tissues, such as water (6 cm)/lung (6 cm)/water (8 cm) with a 3 cm x 3 cm field and water (6 cm)/ bone (2 cm)/water (12 cm) with a 10 cm x 10 cm field; (3) depth dose curves using 6 MeV photon beam based on the CT data of a patient's head and abdomen. The doses based on DPM are compared to the doses calculated by DOSXYZnrc under the same condition. The error was within 3% in water phantom while the error was within 3% in inhomogeneous tissues, except a few points. It has been concluded that the DPM can accurately predict the dose to homogeneous and inhomogeneous tissues.