scholarly journals Study of Photoneutron Production for the 18 MV Photon Beam of the Siemens Medical linac by Monte Carlo Simulation

2019 ◽  
Author(s):  
H Dowlatabadi ◽  
A A Mowlavi ◽  
M Ghorbani ◽  
S Mohammadi ◽  
C Knaup
Keyword(s):  
Neutron Source ◽  
Photon Beam ◽  
Field Size ◽  
Source Strength ◽  
Linear Accelerators ◽  
Flattening Filter Free ◽  
Photon Fluence ◽  
Free Case ◽  
Flattening Filter ◽  
Main Components

Introduction: Considering the importance of photoneutron production in linear accelerators, it is necessary to describe and measure the photoneutrons produced around modern linear accelerators.Material and Methods: The main components of the head of Siemens Primus Plus linac were simulated using MCNPX 2.7.0 code. The contribution of different components of the linac in photoneutron production, neutron source strength, neutron source strength and photon and electron spectra were calculated for the flattening filter and flattening filter free cases for the 18 MV photon beam, and was scored for three fields of 5 × 5 cm2, 10 × 10 cm2 and 20 × 20 cm2 in size.Results: The results show that the primary collimator has the largest contribution to production of neutrons. Moreover, the photon fluence for the flattening filter free case is 8.62, 6.51 and 4.62 times higher than the flattening filter case for the three fields, respectively. The electron fluences for the flattening filter free case are 4.62, 2.93 and 2.79 times higher than with flattening filter case for the three fields under study, respectively. In addition to these cases, by increasing the field size, the contribution of neutron production related to the jaws is reduced, so that when the field size increases from 5 × 5 cm2 to 20 × 20 cm2, a 17.93% decrease in photoneutron production was observed.Conclusion: In all of the accelerators, the neutron strength also increases with increasing energy. The calculated neutron strength was equal to 0.83×1012 neutron Gy −1 at the isocenter.

Study of unflattened photon beams shaped by multileaf collimator using BEAMnrc code

2016 ◽  
Vol 15 (4) ◽  
pp. 392-401
Author(s):  
Ankit kajaria ◽  
Neeraj Sharma ◽  
Shiru Sharma ◽  
Satyajit Pradhan ◽  
Abhijit Mandal ◽  
...  
Keyword(s):  
Beam Line ◽  
Photon Beam ◽  
Field Size ◽  
Photon Beams ◽  
Multileaf Collimators ◽  
Depth Dose ◽  
Beamnrc Code ◽  
Flattening Filter Free ◽  
Flattening Filter ◽  
Beam Delivery

AbstractPurposeIn our study basic dosimetric properties of a flattening filter free 6 MV photon beam shaped by multileaf collimators (MLC) is examined using the Monte Carlo (MC) method.Methods and MaterialsBEAMnrc code was used to make a MC simulation model for 6 MV photon beam based on Varian Clinic 600 unique performance linac, operated with and without a flattening filter in beam line. Dosimetric features including central axis depth dose, beam profiles, photon and electron spectra were calculated and compared for flattened and unflattened cases.ResultsDosimetric field size and penumbra were found to be smaller for unflattened beam, and the decrease in field size was less for MLC shaped in comparison with jaw-shaped unflattened beam. Increase in dose rate of >2·4 times was observed for unflattened beam indicating a shorter beam delivery time for treatment. MLC leakage was found to decrease significantly when the flattening filter was removed from the beam line. The total scatter factor showed slower deviation with field sizes for unflattened beam indicating a reduced head scatter.ConclusionsOur study demonstrated that improved accelerator characteristics can be achieved by removing flattening filter from beam line.

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

scholarly journals Beam flatness modulation for a flattening filter free photon beam utilizing a novel direct leaf trajectory optimization model

2020 ◽  
Vol 21 (3) ◽  
pp. 142-152
Author(s):  
Nicholas J. Potter ◽  
Guanghua Yan ◽  
Hongcheng Liu ◽  
Haitham Alahmad ◽  
Darren L. Kahler ◽  
...  
Keyword(s):  
Optimization Model ◽  
Trajectory Optimization ◽  
Photon Beam ◽  
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 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.

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