scholarly journals A Monte Carlo Study of the Photon Spectrum due to the Different Materials Used in the Construction of Flattening Filters of LINAC

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
J. S. Estepa Jiménez ◽  
M. Díaz Lagos ◽  
S. A. Martinez-Ovalle
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Photon Spectrum ◽  
Original Material ◽  
Advantages And Disadvantages ◽  
Mcnpx Code ◽  
Different Types ◽  
Flattening Filter ◽  
Materials Used ◽  
Photon Spectra

Different types the spectrum of photons were studied; they were emitted from the flattening filter of a LINAC Varian 2100 C/D that operates at 15 MV. The simplified geometry of the LINAC head was calculated using the MCNPX code based on the studies of the materials of the flattening filter, namely, SST, W, Pb, Fe, Ta, Al, and Cu. These materials were replaced in the flattening filter to calculate the photon spectra at the output of this device to obtain the spectrum that makes an impact with the patient. The different spectra obtained were analyzed and compared to the emission from the original spectra configuration of the LINAC, which uses material W. In the study, different combinations of materials were considered in order to establish differences between the use of different materials and the original material, with the objective of establishing advantages and disadvantages from a clinical standpoint.

Dose evaluation of Grid Therapy using a 6 MV flattening filter-free (FFF) photon beam: A Monte Carlo study

2017 ◽  
Vol 44 (10) ◽  
pp. 5378-5383 ◽  
Author(s):  
Immaculada Martínez-Rovira ◽  
Josep Puxeu-Vaqué ◽  
Yolanda Prezado
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Photon Beam ◽  
Dose Evaluation ◽  
Flattening Filter Free ◽  
Flattening Filter

PHOTON BEAM CHARACTERISTICS AT MONITOR CHAMBER LEVEL IN A FLATTENING FILTER FREE LINAC: A MONTE CARLO STUDY

2009 ◽  
Vol 92 ◽  
pp. S57 ◽  
Author(s):  
M. Lind ◽  
T. Knöös ◽  
C. Ceberg ◽  
E. Wieslander ◽  
B. McClean ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Photon Beam ◽  
Flattening Filter Free ◽  
Flattening Filter ◽  
Beam Characteristics

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.

INFLUENCE OF INITIAL STATES ON TWO-TIME DEPENDENCE OF MAGNETORESISANCE IN MULTILAYER STRUCTURES WITH DIFFERENT TYPES OF ANISOTROPY

2020 ◽  
Vol 25 (2) ◽  
pp. 24-33
Author(s):  
Marina Mamonova ◽  
Vladimir Prudnikov ◽  
Pavel Prudnikov ◽  
Anna Samoshilova
Keyword(s):  
Monte Carlo ◽  
Time Dependence ◽  
Monte Carlo Study ◽  
Multilayer Structures ◽  
Aging Effects ◽  
Slow Dynamics ◽  
Magnetic Structures ◽  
Different Types ◽  
Initial States ◽  
Non Equilibrium

The Monte Carlo study of initial states influence on non-equilibrium slow dynamics and two-time dependence of magnetoresistance in multilayer magnetic structures Co/Cu(100)/Co и Pt/Co/Cu(100)/Co/Pt with different types of anisotropy is presented. It was revealed nontrivial aging effects in the magnetoresistance and essential influence of initial states on the magnetoresistance.

scholarly journals Depth Dose Enhancement on Flattening-Filter-Free Photon Beam: A Monte Carlo Study in Nanoparticle-Enhanced Radiotherapy

2020 ◽  
Vol 10 (20) ◽  
pp. 7052
Author(s):  
James C. L. Chow
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Photon Beam ◽  
Depth Range ◽  
Photon Beams ◽  
Dose Enhancement ◽  
Au Nps ◽  
Depth Dose ◽  
Flattening Filter Free ◽  
Flattening Filter

The aim of this study is to investigate the variations of depth dose enhancement (DDE) on different nanoparticle (NP) variables, when using the flattening-filter-free (FFF) photon beam in nanoparticle-enhanced radiotherapy. Monte Carlo simulation under a macroscopic approach was used to determine the DDE ratio (DDER) with variables of NP material (gold (Au) and iron (III) oxide (Fe2O3)), NP concentration (3–40 mg/mL) and photon beam (10 MV flattening-filter (FF) and 10 MV FFF). It is found that Au NPs had a higher DDER than Fe2O3 NPs, when the depths were shallower than 6 and 8 cm for the 10 MV FF and 10 MV FFF photon beams, respectively. However, in a deeper depth range of 10–20 cm, DDER for the Au NPs was lower than Fe2O3 NPs mainly due to the beam attenuation and photon energy distribution. It is concluded that DDER for the Au NPs and Fe2O3 NPs decreased with an increase of depth in the range of 10–20 cm, with rate of decrease depending on the NP material, NP concentration and the use of FF in the photon beam.

Sign in / Sign up

Export Citation Format

Share Document