scholarly journals The Influence of Brass Compensator Thickness and Field Size on Neutron Contamination Spectrum in 18MV Elekta SL 75/25 Medical Linear Accelerator with and without Flattening Filter: A Monte Carlo Study

2018 ◽  
Vol 8 (3Sep) ◽  
Author(s):  
A S Talebi ◽  
M Maleki ◽  
P Hejazi ◽  
M Jadidi ◽  
R Ghorbani
Keyword(s):  
Monte Carlo ◽  
Linear Accelerator ◽  
Monte Carlo Study ◽  
High Energy ◽  
Nonparametric Tests ◽  
Primary Electron ◽  
Field Size ◽  
Dose Ratio ◽  
Medical Linear Accelerator ◽  
Flattening Filter

BackgroundOne of the most significant Intensity Modulated Radiation Therapy treatment benefits is a high target to normal tissue dose ratio. To improve this advantage, an additional accessory such as a compensator is used to delivering doses. Compensator-based IMRT treatment is usually operated with an energy higher than 10 MV. Photoneutrons, which have high linear energy transfer and radiobiological effectiveness, are produced by colliding high-energy photon beams with linear accelerator structures, then they deliver the unwanted doses to patients and staff. Therefore, the neutron energy spectra should be determined in order to calculate and reduce the photoneutron risk.Objective: We have conducted a comprehensive and precise study on the influence of brass compensator thickness and field size on neutron contamination spectrum in an Elekta SL 75/25 medical linear accelerator with and without the flattening filter by Monte Carlo method.Materials and Methods: MCNPX MC Code version 2.6.0 was utilized to simulate the detailed geometry of Elekta SL 75/25 head components based on Linac’s manual. This code includes an important feature to simulate the photo-neutron interactions. Photoneutrons spectrum was calculated after the Linac output benchmarking based on tuning the primary electron beam.Results and Conclusion: Based on the Friedman and Wilcoxon nonparametric tests results (P<0.05), photoneutron fluence directly depends on the field size and compensator thickness. Moreover, the unflattened beam provides lower photoneutron fluence than the flattened beam. Photoneutrons fluence is not negligible in compensator-based IMRT treatment. However, in order to optimize treatment plans, this additional and unwanted dose must be accounted for patients.

scholarly journals [P268] Monte Carlo study of photoneutrons from flattened filter free medical linear accelerator for BNCT applications

2018 ◽  
Vol 52 ◽  
pp. 176-177
Author(s):  
Mohammed Halato ◽  
Gianrossano Giannini ◽  
Francesco Longo ◽  
A. Artoli ◽  
Abdulaziz Alaamer ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Linear Accelerator ◽  
Monte Carlo Study ◽  
Medical Linear Accelerator

scholarly journals Grid Monte Carlo Simulation of a Medical Linear Accelerator

2018 ◽  
Vol 3 (12) ◽  
pp. 40-43 ◽  
Author(s):  
Didi Samir ◽  
Mustapha Zerfaoui ◽  
Abdelilah Moussa ◽  
Yassine Benkhouya ◽  
Mehdi El Ouartiti
Keyword(s):  
Monte Carlo ◽  
Linear Accelerator ◽  
Field Size ◽  
Dose Profile ◽  
Depth Dose ◽  
Grid Simulation ◽  
Medical Linear Accelerator ◽  
Measured Dose ◽  
Better Than ◽  
Good Agreement

A full grid simulation of the head of an Elekta Synergy Platform medical linear accelerator is performed using the Geant4 Monte Carlo platform. The simulation includes all components of the accelerator head and a homogeneous water phantom. Results in terms of depth doses and lateral dose profiles are presented for 6 MV photon beam with the 10x10 cm2 reference field size at 100 cm distance from the source. Overall, a good agreement with the measured dose data is achieved with a precision better than 0.93% and 2.63% for the depth dose profile and lateral dose profiles respectively.

scholarly journals [P263] Monte Carlo study of unflattened versus flattened 18 MV photon beam from medical linear accelerator as photoneutron source for BNCT applications

2018 ◽  
Vol 52 ◽  
pp. 175
Author(s):  
Mohammed Halato ◽  
Ibrahim Suliman ◽  
A. Artoli ◽  
Mohammed Al-Rajhi ◽  
Francesco Longo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Linear Accelerator ◽  
Monte Carlo Study ◽  
Photon Beam ◽  
Medical Linear Accelerator ◽  
Photoneutron Source

scholarly journals Enhancement of the Dose on 12 MV Linac with Free Flattening Filter Mode

2019 ◽  
Author(s):  
A Zeghari ◽  
R Saaidi ◽  
R Cherkaoui El Moursli
Keyword(s):  
Monte Carlo ◽  
Dose Rate ◽  
Monte Carlo Study ◽  
Fold Increase ◽  
Field Size ◽  
Peripheral Dose ◽  
Maximum Increase ◽  
Depth Dose ◽  
Radiotherapy Field ◽  
Flattening Filter

Purpose: In the last years, some studies investigated dosimetric benefits of a free flattening filter for the photon mode in the radiotherapy field. This study aims to provide a theoretical study published and analysis of basic dosimetric properties for a Saturne 43 Linac head to implement free flattening filter beams clinically.Material and Methods: This is the first Monte Carlo study for the head of Saturne 43 with replacement flattening filter mode investigating beam dosimetric characteristics, including central axis absorbed doses, beam profiles and photon energy spectra. The later ones were analyzed for flattening filter and replacement flattening filter beams using BEAMnrc and DOSXYZnrc Monte Carlo codes for 10 × 10 cm2, 5 × 5 cm2 and 2 × 2 cm2 square field sizes.Results: A 3.94-fold increase of dose rate and electron contaminating increased by 246.4 % with the replacement flattening filter mode for field size of 10 × 10 cm2. Reduction was made by replacement flattening filter beam in the peripheral dose up to 30%, and the time was reduced more than 50 %.Conclusion: Results obtained from our study revealed that some characteristic dosimetries such as the maximum increase in depth dose rate, decrease in out-of-depth dose, and reducing time can be beneficial for the unflattened beam to be used in the radiotherapy for the advanced techniques.

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