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Title: SU-E-T-597: Parameterization of the Photon Beam Dosimetry for a Commercial Linear Accelerator

Abstract

Purpose: In radiation therapy, accurate data acquisition of photon beam dosimetric quantities is important for (1) beam modeling data input into a treatment planning system (TPS), (2) comparing measured and TPS modelled data, (3) a linear accelerator’s (linac) beam characteristics quality assurance process, and (4) establishing a standard data set for data comparison, etcetera. Parameterization of the photon beam dosimetry creates a portable data set that is easy to implement for different applications such as those previously mentioned. The aim of this study is to develop methods to parameterize photon percentage depth doses(PDD), profiles, and total scatter output factors(Scp). Methods: Scp, PDDs and profiles for different field sizes (from 2×2 to 40×40cm{sup 2}), depths and energies were measured in a linac using a three-dimensional water tank. All data were smoothed and profile data were also centered, symmetrized and geometrically scaled. The Scp and PDD data were analyzed using exponential functions. For modelling of open and wedge field profiles, each side was divided into three regions described by exponential, sigmoid and Gaussian equations. The model’s equations were chosen based on the physical principles described by these dosimetric quantities. The equations’ parameters were determined using a least square optimization method with themore » minimal amount of measured data necessary. The model’s accuracy was then evaluated via the calculation of absolute differences and distance–to–agreement analysis in low gradient and high gradient regions, respectively. Results: All differences in the PDDs’ buildup and the profiles’ penumbra regions were less than 2 mm and 0.5 mm, respectively. Differences in the low gradient regions were 0.20 ± 0.20% and 0.50 ± 0.35% for PDDs and profiles, respectively. For Scp data, all differences were less than 0.5%. Conclusion: This novel analytical model with minimum measurement requirements proved to accurately calculate PDDs, profiles, and Scp for different field sizes, depths and energies.« less

Authors:
; ; ; ; ; ;  [1]
  1. Univ Florida, Gainesville, FL (United States)
Publication Date:
OSTI Identifier:
22496310
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
61 RADIATION PROTECTION AND DOSIMETRY; 62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; DATA ACQUISITION; DATA ANALYSIS; DATASETS; DEPTH DOSE DISTRIBUTIONS; DOSIMETRY; EQUATIONS; LINEAR ACCELERATORS; PHOTON BEAMS; QUALITY ASSURANCE; RADIOTHERAPY; SIMULATION

Citation Formats

Lebron, S, Lu, B, Yan, G, Kahler, D, Li, J, Barraclough, B, and Liu, C. SU-E-T-597: Parameterization of the Photon Beam Dosimetry for a Commercial Linear Accelerator. United States: N. p., 2015. Web. doi:10.1118/1.4924960.
Lebron, S, Lu, B, Yan, G, Kahler, D, Li, J, Barraclough, B, & Liu, C. SU-E-T-597: Parameterization of the Photon Beam Dosimetry for a Commercial Linear Accelerator. United States. doi:10.1118/1.4924960.
Lebron, S, Lu, B, Yan, G, Kahler, D, Li, J, Barraclough, B, and Liu, C. Mon . "SU-E-T-597: Parameterization of the Photon Beam Dosimetry for a Commercial Linear Accelerator". United States. doi:10.1118/1.4924960.
@article{osti_22496310,
title = {SU-E-T-597: Parameterization of the Photon Beam Dosimetry for a Commercial Linear Accelerator},
author = {Lebron, S and Lu, B and Yan, G and Kahler, D and Li, J and Barraclough, B and Liu, C},
abstractNote = {Purpose: In radiation therapy, accurate data acquisition of photon beam dosimetric quantities is important for (1) beam modeling data input into a treatment planning system (TPS), (2) comparing measured and TPS modelled data, (3) a linear accelerator’s (linac) beam characteristics quality assurance process, and (4) establishing a standard data set for data comparison, etcetera. Parameterization of the photon beam dosimetry creates a portable data set that is easy to implement for different applications such as those previously mentioned. The aim of this study is to develop methods to parameterize photon percentage depth doses(PDD), profiles, and total scatter output factors(Scp). Methods: Scp, PDDs and profiles for different field sizes (from 2×2 to 40×40cm{sup 2}), depths and energies were measured in a linac using a three-dimensional water tank. All data were smoothed and profile data were also centered, symmetrized and geometrically scaled. The Scp and PDD data were analyzed using exponential functions. For modelling of open and wedge field profiles, each side was divided into three regions described by exponential, sigmoid and Gaussian equations. The model’s equations were chosen based on the physical principles described by these dosimetric quantities. The equations’ parameters were determined using a least square optimization method with the minimal amount of measured data necessary. The model’s accuracy was then evaluated via the calculation of absolute differences and distance–to–agreement analysis in low gradient and high gradient regions, respectively. Results: All differences in the PDDs’ buildup and the profiles’ penumbra regions were less than 2 mm and 0.5 mm, respectively. Differences in the low gradient regions were 0.20 ± 0.20% and 0.50 ± 0.35% for PDDs and profiles, respectively. For Scp data, all differences were less than 0.5%. Conclusion: This novel analytical model with minimum measurement requirements proved to accurately calculate PDDs, profiles, and Scp for different field sizes, depths and energies.},
doi = {10.1118/1.4924960},
journal = {Medical Physics},
number = 6,
volume = 42,
place = {United States},
year = {Mon Jun 15 00:00:00 EDT 2015},
month = {Mon Jun 15 00:00:00 EDT 2015}
}