Comparison of measured and Monte Carlo calculated dose distributions from indigenously developed 6 MV flattening filter free medical linear accelerator

AbstractAn Elekta Synergy LINAC was used to investigate the beam quality index Q and the beam quality correction factor kQ, which is used for absolute dosimetry, in off-axis photon fields. It was found that the beam quality index Q of the photon energies with flattening filter decreases with increasing distance to the central axis, at 6 MV by 4.27% and at 15 MV by 3.98% inside a range of 15 cm off-axis. The beam quality index for flattening filter free photon fields also decreases with increasing distance to the central axis. In this case Q changed only by 1.01% inside the above range.

Download Full-text

Analysis of physical parameters and determination of inflection point for Flattening Filter Free beams in medical linear accelerator

Reports of Practical Oncology & Radiotherapy ◽

10.1016/j.rpor.2014.01.004 ◽

2014 ◽

Vol 19 (5) ◽

pp. 322-331 ◽

Cited By ~ 7

Author(s):

A. Pichandi ◽

Kadirampatti Mani Ganesh ◽

Amalraj Jerin ◽

Karunakaran Balaji ◽

Gurunath Kilara

Keyword(s):

Linear Accelerator ◽

Inflection Point ◽

Physical Parameters ◽

Medical Linear Accelerator ◽

Flattening Filter Free ◽

Flattening Filter

Download Full-text

Treatment vault shielding for a flattening filter-free medical linear accelerator

Physics in Medicine and Biology ◽

10.1088/0031-9155/54/5/011 ◽

2009 ◽

Vol 54 (5) ◽

pp. 1265-1273 ◽

Cited By ~ 18

Author(s):

Stephen F Kry ◽

Rebecca M Howell ◽

Jerimy Polf ◽

Radhe Mohan ◽

Oleg N Vassiliev

Keyword(s):

Linear Accelerator ◽

Medical Linear Accelerator ◽

Flattening Filter Free ◽

Flattening Filter

Download Full-text

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.

Download Full-text

Open beam dosimetric characteristics of True Beam medical linear accelerator with flattening filter (WFF) and flattening filter free (FFF) beam

Polish Journal of Medical Physics and Engineering ◽

10.2478/pjmpe-2018-0011 ◽

2018 ◽

Vol 24 (2) ◽

pp. 79-89 ◽

Cited By ~ 1

Author(s):

Karthick Raj Mani ◽

Md Anisuzzaman Bhuiyan ◽

Md. Shakilur Rahman ◽

S. M. Azharur Islam

Keyword(s):

Dose Rate ◽

Linear Accelerator ◽

Maximum Dose ◽

Published Data ◽

Depth Dose ◽

Medical Linear Accelerator ◽

Flattening Filter Free ◽

Dosimetric Data ◽

Flattening Filter ◽

Maximum Dose Rate

Abstract True Beam medical linear accelerator is capable of delivering flattening filter free (FFF) and with flattening filter (WFF) photon beams. True Beam linear accelerator is equipped with five photon beam energies (6 FFF, 6 WFF, 10 FFF, 10 WFF and 15 WFF) as well as six electron beam energies (6 MeV, 9 MeV, 12 MeV, 15 MeV and 18 MeV). The maximum dose rate for the 6 WFF, 10 WFF and 15 WFF is 600 MU/min, whereas 6 FFF has a maximum dose rate of 1400 MU/min and 10 FFF with a maximum dose rate of 2400 MU/min. In this report we discussed the open beam dosimetric characteristics of True Beam medical linear accelerator with FFF and WFF beam. All the dosimetric data (i.e. depth dose, cross-line profiles, diagonal profiles, output factors, MLC transmission, etc.) for 6 MV, 6 FFF, 10 MV, 10 FFF and 15 MV were measured and compared with the published data of the True Beam. Multiple detectors were used in order to obtain a consistent dataset. The measured data has a good consistency with the reference golden beam data. The measured beam quality index for all the beams are in good agreement with the published data. The percentage depth dose at 10 cm depth of all the available photon beams was within the tolerance of the Varian acceptance specification. The dosimetric data shows consistent and comparable results with the published data of other True Beam linear accelerators. The dosimetric data provide us an appreciated perception and consistent among the published data and may be used for future references.

Download Full-text