A proton dose simulation system based on the pencil beam calculation algorithm.

• Main Authors: Fan Chang, 張帆
• Other Authors: C. C. Lee
• Format: Others
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/65124090971436442445

碩士 === 長庚大學 === 醫學影像暨放射科學系 === 101 === Dose simulation is a critical measure before a real treatment can be delivered for proton therapy. Monte Carlo simulations and/or analytical algorithms are used in dose simulation to predict dose distribution of proton beam irradiation. In this study, a pencil beam calculation algorithm was adopted to establish a proton dose simulation system. Our pencil beam calculation algorithm was based on the publication from Hong of Massachusetts General Hospital and implented using the MATLAB package. The primary simulation parameters of a basic pencil beam are its lateral distribution and percent depth dose (PDD). Proton dose distribution of a finite field in a medium can be calculated by integration of distributions of the beam fluence and the basic pencil beam using either the error function method or the convolution method. In this study, the lateral distribution was calculated by Hong’s equations and the PDDs were simulated by Genat4. We have successfully established a preliminary proton dose simulation system to calculate dose distributions of small uniform fields, broad uniform fields and broad non-uniform fields for 110 and 160 MeV proton beams. Due to numerical error caused by discrete sampling of the convolution method, dose difference can be found at the field edge. It can be reduced by increasing the sampling size. In the present work, all proton beams are parallelly irradiated into an uniform water phantom and we do not consider beam divergence.