Monte Carlo study of the influence of energy spectra, mesh size, high Z element on dose and PVDR based on 1-D and 3-D heterogeneous mouse head phantom for Microbeam Radiation Therapy

Abstract Purpose To evaluate the influence of energy spectra, mesh sizes, high Z element on dose and PVDR in Microbeam Radiation Therapy (MRT) based on 1-D analogy-mouse-head-model (1-D MHM) and 3-D voxel-mouse-head-phantom (3-D VMHP) by Monte Carlo simulation. Methods A Microbeam-Array-Source-Model was implemented into EGSnrc/DOSXYZnrc. The microbeam size is assumed to be 25 μm, 50 μm or 75 μm in thickness and fixed 1 mm in height with 200 μm c-t-c. The influence of the energy spectra of ID17@ESRF and BMIT@CLS were investigated. The mesh size was optimized. PVDR in 1-D MHM and 3-D VMHP was compared with the homogeneous water phantom. The arc influence of 3-D VMHP filled with water (3-D VMHWP) was compared with the rectangle phantom. Results PVDR of the lower BMIT@CLS spectrum is 2.4 times that of ID17@ESRF for lower valley dose. The optimized mesh is 5 µm for 25 µm, and 10 µm for 50 µm and 75 µm microbeams with 200 µm c-t-c. A 500 μm skull layer could make PVDR difference up to 62.5% for 1-D MHM. However this influence is limited ( Conclusion An accurate MRT dose calculation algorithm should include the influence of 3-D heterogeneous media.