scholarly journals Monte Carlo Study of Unflattened Photon Beams Shaped by Multileaf Collimator

2019 ◽  
Vol 9 (2Apr) ◽  
Author(s):  
A Kajaria ◽  
N Sharma ◽  
Sh Sharma ◽  
S Pradhan ◽  
A Mandal ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Beam Line ◽  
Photon Beam ◽  
Multileaf Collimator ◽  
Photon Beams ◽  
Peripheral Dose ◽  
Depth Dose ◽  
Field Edge ◽  
Flattening Filter

Introduction: This study investigates basic dosimetric properties of unflattened 6 MV photon beam shaped by multileaf collimator and compares them with those of flattened beams.Materials and Methods: Monte Carlo simulation model using BEAM code was developed for a 6MV photon beam based on Varian Clinic 600 unique performance linac operated with and without a flattening filter in beam line. Dosimetric features including lateral profiles, central axis depth dose, photon and electron spectra were calculated for flattened and unflattened cases, separately.Results: An increase in absolute depth dose with a factor of more than 2.4 was observed for unflattened beam which was dependent on depth. PDDs values were found to be lower for unflattened beam for all field sizes. Significant decrease in calculated mlc leakage was observed when the flattening filter was removed from the beam line. The total scatter factor, SCP was found to show less variation with field sizes for unflattened beam indicating a decrease in head scatter. The beam profiles for unflattened case are found to have lower relative dose value in comparison with flattened beam near the field edge, and it falls off faster with distance.Conclusion: Our study showed that increase in the dose rate and lower peripheral dose could be considered as realistic advantages for unflattened 6MV photon beams.

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.

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.

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.

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 Contrast Enhancement for Portal Imaging in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Evaluation Using Flattening-Filter-Free Photon Beams

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 920 ◽  
Author(s):  
Aniza Abdulle ◽  
James C. L. Chow
Keyword(s):  
Monte Carlo ◽  
Contrast Enhancement ◽  
Beam Energy ◽  
Photon Beam ◽  
Nanoparticle Concentration ◽  
Photon Beams ◽  
Portal Imaging ◽  
Flattening Filter Free ◽  
Rate Of Increase ◽  
Flattening Filter

Our team evaluated contrast enhancement for portal imaging using Monte Carlo simulation in nanoparticle-enhanced radiotherapy. Dependencies of percentage contrast enhancement on flattening-filter (FF) and flattening-filter-free (FFF) photon beams were determined by varying the nanoparticle material (gold, platinum, iodine, silver, iron oxide), nanoparticle concentration (3–40 mg/mL) and photon beam energy (6 and 10 MV). Phase-space files and energy spectra of the 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF photon beams were generated based on a Varian TrueBeam linear accelerator. We found that gold and platinum nanoparticles (NP) produced the highest contrast enhancement for portal imaging, compared to other NP with lower atomic numbers. The maximum percentage contrast enhancements for the gold and platinum NP were 18.9% and 18.5% with a concentration equal to 40 mg/mL. The contrast enhancement was also found to increase with the nanoparticle concentration. The maximum rate of increase of contrast enhancement for the gold NP was equal to 0.29%/mg/mL. Using the 6 MV photon beams, the maximum contrast enhancements for the gold NP were 79% (FF) and 78% (FFF) higher than those using the 10 MV beams. For the FFF beams, the maximum contrast enhancements for the gold NP were 53.6% (6 MV) and 53.8% (10 MV) higher than those using the FF beams. It is concluded that contrast enhancement for portal imaging can be increased when a higher atomic number of NP, higher nanoparticle concentration, lower photon beam energy and no flattening filter of photon beam are used in nanoparticle-enhanced radiotherapy.

scholarly journals Dose Enhancement for the Flattening-Filter-Free and Flattening-Filter Photon Beams in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Study

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 637 ◽  
Author(s):  
Stefano Martelli ◽  
James C L Chow
Keyword(s):  
Monte Carlo ◽  
Photon Beam ◽  
Nanoparticle Concentration ◽  
Photon Beams ◽  
Target Dose ◽  
Flattening Filter Free ◽  
Prostate Size ◽  
Flattening Filter ◽  
Pelvic Size ◽  
Nanoparticle Material

Monte Carlo simulations were used to predict the dose enhancement ratio (DER) using the flattening-filter-free (FFF) and flattening-filter (FF) photon beams in prostate nanoparticle-enhanced radiotherapy, with multiple variables such as nanoparticle material, nanoparticle concentration, prostate size, pelvic size, and photon beam energy. A phantom mimicking the patient’s pelvis with various prostate and pelvic sizes was used. Macroscopic Monte Carlo simulation using the EGSnrc code was used to predict the dose at the prostate or target using the 6 MV FFF, 6 MV FF, 10 MV FFF, and 10 MV FF photon beams produced by a Varian TrueBeam linear accelerator (Varian Medical System, Palo Alto, CA, USA). Nanoparticle materials of gold, platinum, iodine, silver, and iron oxide with concentration varying in the range of 3–40 mg/ml were used in simulations. Moreover, the prostate and pelvic size were varied from 2.5 to 5.5 cm and 20 to 30 cm, respectively. The DER was defined as the ratio of the target dose with nanoparticle addition to the target dose without nanoparticle addition in the simulation. From the Monte Carlo results of DER, the best nanoparticle material with the highest DER was gold, based on all the nanoparticle concentrations and photon beams. Smaller prostate size, smaller pelvic size, and a higher nanoparticle concentration showed better DER results. When comparing energies, the 6 MV beams always had the greater enhancement ratio. In addition, the FFF photon beams always had a better DER when compared to the FF beams. It is concluded that gold nanoparticles were the most effective material in nanoparticle-enhanced radiotherapy. Moreover, lower photon beam energy (6 MV), FFF photon beam, higher nanoparticle concentration, smaller pelvic size, and smaller prostate size would all increase the DER in prostate nanoparticle-enhanced radiotherapy.

Dosimetric properties of a flattening filter-free 6-MV photon beam: a Monte Carlo study

2007 ◽  
Vol 25 (7) ◽  
pp. 315-324 ◽  
Author(s):  
Asghar Mesbahi ◽  
Parinaz Mehnati ◽  
Ahmad Keshtkar ◽  
Alireza Farajollahi
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Photon Beam ◽  
Flattening Filter Free ◽  
Flattening Filter
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