Grid Monte Carlo Simulation of a Medical Linear Accelerator

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.

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Benchmarking of Siemens Linac in Electron Modes: 8-14 MeV Electron Beams

Journal of Biomedical Physics and Engineering ◽

10.31661/jbpe.v8i2.806 ◽

2018 ◽

Vol 8 (2) ◽

Cited By ~ 1

Author(s):

H Dowlatabadi ◽

A A Mowlavi ◽

M Ghorbani ◽

S Mohammadi ◽

F Akbari

Keyword(s):

Monte Carlo ◽

Radiation Treatment ◽

Electron Beams ◽

Dose Profile ◽

Depth Dose ◽

Mcnpx Code ◽

Gamma Index ◽

Simulation Results ◽

Mc Simulation ◽

Good Agreement

Introduction: Radiation therapy using electron beams is a promising method due to its physical dose distribution. Monte Carlo (MC) code is the best and most accurate technique for forespeaking the distribution of dose in radiation treatment of patients.Materials and Methods: We report an MC simulation of a linac head and depth dose on central axis, along with profile calculations. The purpose of the present research is to carefully analyze the application of MC methods for the calculation of dosimetric parameters for electron beams with energies of 8–14 MeV at a Siemens Primus linac. The principal components of the linac head were simulated using MCNPX code for different applicators. Results: The consequences of measurements and simulations revealed a good agreement. Gamma index values were below 1 for most points, for all energy values and all applicators in percent depth dose and dose profile computations. A number of states exhibited rather large gamma indices; these points were located at the tail of the percent depth dose graph; these points were less used in in radiotherapy. In the dose profile graph, gamma indices of most parts were below 1. The discrepancies between the simulation results and measurements in terms of Zmax, R90, R80 and R50 were insignificant. The results of Monte Carlo simulations showed a good agreement with the measurements. Conclusion: The software can be used for simulating electron modes of a Siemens Primus linac when direct experimental measurements are not feasible.

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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

Journal of Biomedical Physics and Engineering ◽

10.31661/jbpe.v8i3sep.918 ◽

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.

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FLUKA Monte Carlo for Basic Dosimetric Studies of Dual Energy Medical Linear Accelerator

Journal of Radiotherapy ◽

10.1155/2014/343979 ◽

2014 ◽

Vol 2014 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

K. Abdul Haneefa ◽

T. Siji Cyriac ◽

M. M. Musthafa ◽

R. Ganapathi Raman ◽

V. T. Hridya ◽

...

Keyword(s):

Monte Carlo ◽

Linear Accelerator ◽

Dual Energy ◽

General Purpose ◽

Experimental Measurements ◽

Monte Carlo Code ◽

Percentage Depth Dose ◽

Depth Dose ◽

Medical Linear Accelerator ◽

Cylindrical Ionization Chamber

General purpose Monte Carlo code for simulation of particle transport is used to study the basic dosimetric parameters like percentage depth dose and dose profiles and compared with the experimental measurements from commercial dual energy medical linear accelerator. Varian Clinac iX medical linear accelerator with dual energy photon beams (6 and 15 MV) is simulated using FLUKA. FLAIR is used to visualize and edit the geometry. Experimental measurements are taken for 100 cm source-to-surface (SSD) in 50 × 50 × 50 cm3 PTW water phantom using 0.12 cc cylindrical ionization chamber. Percentage depth dose for standard square field sizes and dose profiles for various depths are studied in detail. The analysis was carried out using ROOT (a DATA analysis frame work developed at CERN) system. Simulation result shows good agreement in percentage depth dose and beam profiles with the experimental measurements for Varian Clinac iX dual energy medical linear accelerator.

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Method for calculation the absolute dose in the Monte Carlo simulation

Science and Technology Development Journal - Natural Sciences ◽

10.32508/stdjns.v2i5.783 ◽

2019 ◽

Vol 2 (5) ◽

pp. 90-96

Author(s):

Oanh Thi Luong ◽

Luong Thanh Dang ◽

Tai Thanh Duong

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

General Hospital ◽

Dose Distribution ◽

Linear Accelerator ◽

Photon Beams ◽

Ion Chamber ◽

Measured Dose ◽

The Absolute ◽

Good Agreement

In this study, we presented the method for calculation the absolute dose in the Monte Carlo simulation following the prescription of Popescu et al for the 6 MV photon energy. The BEAMnrc was used to simulate 6 MV photon beams from a Siemens Primus M5497 linear accelerator at DongNai general hospital. The DOSXYZnrc was then used to calculate the dose distribution in a homogeneous phantom (in form of CT images). The absolute dose obtained from the MC and TPS were compared with measured ones using an ion chamber (Farmer Type Chamber FC65-P, IBA). The average doses discrepancy between the simulated and measured dose was 0.53±0.37% and between the simulated and TPS was 1.00±0.51%. Results showed good agreement between simulated, measured and calculated dosed on a homogeneous phantom.

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Dosimetric characterization of medical linear accelerator Photon and Electron beams for the treatment accuracy of cancer patients

World Journal of Advanced Engineering Technology and Sciences ◽

10.30574/wjaets.2021.3.1.0046 ◽

2021 ◽

Vol 3 (1) ◽

pp. 041-059

Author(s):

Motiur Rahman ◽

M Shamsuzzaman ◽

Manoshi Sarker ◽

Abdul Jobber ◽

Mohsin Mia ◽

...

Keyword(s):

Linear Accelerator ◽

Planning Process ◽

Electron Beams ◽

Small Deviation ◽

Beam Profile ◽

Field Size ◽

Photon Beams ◽

Depth Dose ◽

Medical Linear Accelerator

In radiotherapy treatment planning process, quality assessment (QA) is indispensable for achieving accuracy and avoidance of treatment errors. In this perspective, present study focused on the Photon and Electron beams characterization of a medical linear accelerator (LINAC) to ascertain dosimetric QA in Absolute and Reference dosimetry. In this connection, the beam outputs were investigated in terms of Dmax and Dw,max (dose at depth dmax) in absolute dosimetry for Photon and Electron beams, respectively. In accordance with the measured Dmax and Dw,max parameters, Photon and Electron beam outputs were standardized to ensure standard output of 1 cGy/MU. In reference dosimetry, the parametric evaluation was performed for dosimetric QA in terms of percent depth dose (PDD), beam profile flatness and symmetry, output factors: Scp, Sc, Sp with varying field size (FS) ranging from 4´4 cm2 to 40´40 cm2 normalized at FS 10´10 cm2 for the 6 MV and 10 MV Photon beams. The measured PDDs at 10 cm depth (D10) were found to be 66.8% and 73.6% for 6 MV and 10 MV Photon beams, respectively, with significantly small deviation of 1% and 0.8% in comparison with an international PDD protocol of British Journal of Radiology-25 (BJR -25). In the case of Electron beams characterization, PDD was verified with 10´10 cm2 cone/applicator, beam profile flatness and symmetry were analyzed at the field sizes ranging from 6´6 cm2 to 25´25 cm2 normalized at 10´10 cm2 cone/applicator, and Electron cone ratios were investigated for a given cone/applicator relative to the 15´15 cm2 one for the 6, 9, 12, 15 MeV Electron energies. The PDDs of all the Electron beams revealed reasonable consistency with manufacturer’s estimations of 90%, 80%, and 50% PDDs at various depths of ionization.

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