Monte Carlo N-particle (MCNP) simulation of prostate cancer brachytherapy with edema and I-125 seed displacement

• Main Author: Almanza, Dustin Lorenz V.
• Format: text
• Language: English
• Published: Animo Repository 2018
• Subjects: Prostate; Prostate > Cancer; Edema
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5540
• Institution: De La Salle University

In prostate cancer brachytherapy, edema and source displacement are not accounted for in treatment planning. Edema or swelling of the prostate, results from trauma due to source implantation. The increase in prostate volume due to trauma results to source displacement that can affect the delivered dose in the prostate. Deviation from the prescribed dose might not only affect the target volume but also the surrounding healthy tissues and organs. The actual dose delivered and the deviations are difficult to quantify in prostate brachytherapy. Thus, MCNP is a useful tool in quantifying these variations. This paper aims to determine the dose variation due to edema and source displacement in Iodine-125 prostate brachytherapy via MCNP simulation. The prostate volume (33.5cc), percent edema (31%, 21%, 15% and 5%), and source displacement (0.2cm) used in the study were based on actual clinical data from various references. In general, decrease in the deposited dose with increasing prostate edema were observed. Result shows that considering edema and seed displacement, the largest edema (31%) has 23.92% and smallest edema (5%) has 5.4% difference compared when edema and seed displacement were not considered. Comparing simulations with and without seed displacement in all percent edema, lower dose was received by the prostate when seed displacement was considered. Result shows that considering edema with displacement, the largest edema (31%) and smallest edema (5%) have 1.00 Gy and 1.56 Gy maximum difference when compared with no seed displacement. Almost all the statistical tests included in the MCNP simulation output passed with deviations within the range of acceptable values. This study was able to show the difference in the dose received by the prostate when various percent edema and seed displacement were considered.