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Title: SU-E-T-650: Quantification and Modeling of the Dosimetric Impact of the IBEAM Evo Treatment Couchtop EP (Elekta) in VMAT

Abstract

Purpose: quantification and modelling of the dosimetric impact of the treatment couch in Monaco Treatment Planning System. Methods: The attenuation characteristics of couchtop EP was evaluated for two different photon acceleration potentials (6MV and 10MV) for a field size of (10×10) cm2. Phantom positions in A-B direction: on the left half, in the center and on the right half of the couch. Dose measurements of couch attenuation were performed at gantry angles from 180° to 122°, using a 0.125cc semiflex ionization chamber isocentrically placed in the center of a homogeneous cylindric sliced RW3 phantom. Each experimental setup was first measured on the LINAC and then reproduced in the TPS. By adjusting the relative-to-water electron density (ED) values of the couch, the measured attenuation was replicated. The simulated results were evaluated by comparing the measurements and simulations. Results: Without the couch model included the maximum difference between measured and calculated dose was 5.5% (5.1%) and 6.6% (6.1%) for 2 mm and 5 mm voxel size, when the phantom was positioned on the left (center). The couch model was included in the TPS with a uniform ED of 0.18 or a 2 component model with a fiber ED= 0.6 and foam coremore » ED= 0.1. After including the treatment couch, the mean dose attenuation was reduced from 2.8% without couch included to (0.0, 0.8, −0.2, 0.6)%. The 4 different values represent the 1 and 2 components model and 2 and 5 mm voxel grid size. Conclusion: For a uniform relative-to-water couch electron density of 0.18 a good agreement between measured and calculated dose distributions was obtained for all different energies, voxel grid spacings and gantry angles. Therefore, we conclude that the Monaco couch model accurately describes the dose perturbations due to the presence of the patient couch and should therefore be used during treatment planning. This project is supported by Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Hebei Personnel of China.« less

Authors:
 [1];  [2];  [1];  [3]
  1. The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei (China)
  2. (Germany)
  3. Mannheim Medical Center, Mannheim, Baden-Wurttemberg (Germany)
Publication Date:
OSTI Identifier:
22538159
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:
62 RADIOLOGY AND NUCLEAR MEDICINE; 61 RADIATION PROTECTION AND DOSIMETRY; ATTENUATION; ELECTRON DENSITY; IONIZATION CHAMBERS; LINEAR ACCELERATORS; PHANTOMS; RADIATION DOSE DISTRIBUTIONS; RADIOTHERAPY; SIMULATION

Citation Formats

Zhang, R, Mannheim Medical Center, Mannheim, Baden-Wurttemberg, Bai, W, and Fleckenstein, J. SU-E-T-650: Quantification and Modeling of the Dosimetric Impact of the IBEAM Evo Treatment Couchtop EP (Elekta) in VMAT. United States: N. p., 2015. Web. doi:10.1118/1.4925013.
Zhang, R, Mannheim Medical Center, Mannheim, Baden-Wurttemberg, Bai, W, & Fleckenstein, J. SU-E-T-650: Quantification and Modeling of the Dosimetric Impact of the IBEAM Evo Treatment Couchtop EP (Elekta) in VMAT. United States. doi:10.1118/1.4925013.
Zhang, R, Mannheim Medical Center, Mannheim, Baden-Wurttemberg, Bai, W, and Fleckenstein, J. Mon . "SU-E-T-650: Quantification and Modeling of the Dosimetric Impact of the IBEAM Evo Treatment Couchtop EP (Elekta) in VMAT". United States. doi:10.1118/1.4925013.
@article{osti_22538159,
title = {SU-E-T-650: Quantification and Modeling of the Dosimetric Impact of the IBEAM Evo Treatment Couchtop EP (Elekta) in VMAT},
author = {Zhang, R and Mannheim Medical Center, Mannheim, Baden-Wurttemberg and Bai, W and Fleckenstein, J},
abstractNote = {Purpose: quantification and modelling of the dosimetric impact of the treatment couch in Monaco Treatment Planning System. Methods: The attenuation characteristics of couchtop EP was evaluated for two different photon acceleration potentials (6MV and 10MV) for a field size of (10×10) cm2. Phantom positions in A-B direction: on the left half, in the center and on the right half of the couch. Dose measurements of couch attenuation were performed at gantry angles from 180° to 122°, using a 0.125cc semiflex ionization chamber isocentrically placed in the center of a homogeneous cylindric sliced RW3 phantom. Each experimental setup was first measured on the LINAC and then reproduced in the TPS. By adjusting the relative-to-water electron density (ED) values of the couch, the measured attenuation was replicated. The simulated results were evaluated by comparing the measurements and simulations. Results: Without the couch model included the maximum difference between measured and calculated dose was 5.5% (5.1%) and 6.6% (6.1%) for 2 mm and 5 mm voxel size, when the phantom was positioned on the left (center). The couch model was included in the TPS with a uniform ED of 0.18 or a 2 component model with a fiber ED= 0.6 and foam core ED= 0.1. After including the treatment couch, the mean dose attenuation was reduced from 2.8% without couch included to (0.0, 0.8, −0.2, 0.6)%. The 4 different values represent the 1 and 2 components model and 2 and 5 mm voxel grid size. Conclusion: For a uniform relative-to-water couch electron density of 0.18 a good agreement between measured and calculated dose distributions was obtained for all different energies, voxel grid spacings and gantry angles. Therefore, we conclude that the Monaco couch model accurately describes the dose perturbations due to the presence of the patient couch and should therefore be used during treatment planning. This project is supported by Technology Foundation for Selected Overseas Chinese Scholar, Ministry of Hebei Personnel of China.},
doi = {10.1118/1.4925013},
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}
}