Assessment of The Relation Between Energy Of Primary Protons And Undesired Neutron Dose During Proton Therapy By Monte Carlo Method
author
Abstract:
Introduction: High-energy beams of protons offer significant advantages for the treatment of deepseated local tumors. Their physical depth-dose distribution in tissue is characterized by a small entrance dose and a distinct maximum -Bragg peak- near the end of range with a sharp fall-off at the distal edge. Alongside its advantages there are some point that they need to meticulous attention. Producing dose due to secondary particles is one of the important challenges in proton therapy. Materials and Methods: In the first stage the head was simulated by a cylindrical water phantom with length of 19cm and diameter of 19cm with 0.5 cm thickness of plexiglass. Then proton characteristics such as depth-dose distribution were investigated. In the next stage to evaluate the effect of variation of target density on depth-dose distribution, density of phantom materials varied. Increasing tissue density by 5% proton dose was decreased. Then a spherical tumor with diameter of 1cm in the phantom was considered and calculation of dose performed in the tumor and phantom. We have applied the MCNPX version of 2.6.0 code for proton beam energies ranging from 150 to 160 MeV, with steps of 1MeV, to obtain the ionization values, which are related to the cell damage or dose, in the target. MCNPX code is a general purpose radiation transport simulation code which is capable to simulate proton beams. This code requires an input file data that defines the geometry, the physical parameters and the tallies of the simulated problem. Results: results have good agreement with results of TRIM package. Protons with 160 MeV energy have bragg peak in 17.1 cm and it has value of 1.237e-11 Gy/ source particles . we found that, for each 5 MeV increase for energy of protons, dose increase about 4.28%. after calculating dose for 11 steps between 150 and 160 MeV, proton by 153 MeV energy have the best dose distribution because it has maximum dose in tumor area and minimum dose for healthy tissue. Again simulation with TRIM code confirm this result. And also we found secondary neutron dose was found to be 100 orders lower than primary proton dose. Further providing evidence that secondary dose is relatively small in proton therapy. Conclusion: Energy of entranced protons has significant effect on production of neutrons so it is helpful to use optimum energy for proton therapy especially for sensitive part of the body like brain, because neutron dose during proton therapy may increase the risk of metastases cancer.
similar resources
Dose Assessment of Eye and Its Components in Proton Therapy by Monte Carlo Method
Introduction Proton therapy is used to treat malignant tumors such as melanoma inside the eye. Proton particles are adjusted according to various parameters such as tumor size and position and patient’s distance from the proton source. The purpose of this study was to assess absorbed doses in eyes and various tumors found in the area of sclera and choroid and the adjacent tissues in radiotherap...
full textdose assessment of eye and its components in proton therapy by monte carlo method
introduction proton therapy is used to treat malignant tumors such as melanoma inside the eye. proton particles are adjusted according to various parameters such as tumor size and position and patient’s distance from the proton source. the purpose of this study was to assess absorbed doses in eyes and various tumors found in the area of sclera and choroid and the adjacent tissues in radiotherap...
full textDose Assessment of Eye and Its Components in Proton Therapy by Monte Carlo Method
Introduction Proton therapy is used to treat malignant tumors such as melanoma inside the eye. Proton particles are adjusted according to various parameters such as tumor size and position and patient’s distance from the proton source. The purpose of this study was to assess absorbed doses in eyes and various tumors found in the area of sclera and choroid and the adjacent tissues in radiotherap...
full textMonte Carlo calculations of dose distribution for the treatment of gastric cancer with proton therapy
Proton therapy is a common form of external radiation therapy based on the manipulation of Bragg peak of this beam, it can treat the tumor by delivering high levels of doses to it, while protecting surrounding healthy tissues against radiation. In this work, the dose distribution of proton and secondary particles such as neutrons, photons, electrons and positrons in gastric cancer proton therap...
full textAssessment of secondary particles in breast proton therapy by Monte Carlo simulation code using MCNPX
Background: The present study aimed to investigate the equivalent dose in vital organs, including heart and lung, due to secondary particles produced during breast proton therapy. Materials and Methods: The numerical ORNL female-phantom was improved and simulated using the Monte Carlo MCNPX code. The depth-dose profile of proton beams with different energies was simulated. The proper energy ran...
full textCalculating Reaction Rate of Positron Emitters During Proton Therapy Which Are Used In Online PET Scan by Monte Carlo Method
Introduction: Nowadays, cancer is one of the most important concerns in human being's societies, more than one-third of people in around the world will get cancer during their lives. Physical dose depth distribution characteristic of protons in a tissue is determined with a low dose in the entrance region, maximum dose in the Bragg region, and rapid decline takes place near the...
full textMy Resources
Journal title
volume 15 issue Special Issue-12th. Iranian Congress of Medical Physics
pages 64- 64
publication date 2018-12-01
By following a journal you will be notified via email when a new issue of this journal is published.
Hosted on Doprax cloud platform doprax.com
copyright © 2015-2023