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Title: Study on surface dose generated in prostate intensity-modulated radiation therapy treatment

Abstract

The surface doses of 6- and 15-MV prostate intensity-modulated radiation therapy (IMRT) irradiations were measured and compared to those from a 15-MV prostate 4-beam box (FBB). IMRT plans (step-and-shoot technique) using 5, 7, and 9 beams with 6- and 15-MV photon beams were generated from a Pinnacle treatment planning system (version 6) using computed tomography (CT) scans from a Rando Phantom (ICRU Report 48). Metal oxide semiconductor field effect transistor detectors were used and placed on a transverse contour line along the Phantom surface at the central beam axis in the measurement. Our objectives were to investigate: (1) the contribution of the dynamic multileaf collimator (MLC) to the surface dose during the IMRT irradiation; (2) the effects of photon beam energy and number of beams used in the IMRT plan on the surface dose. The results showed that with the same number of beams used in the IMRT plan, the 6-MV irradiation gave more surface dose than that of 15 MV to the phantom. However, when the number of beams in the plan was increased, the surface dose difference between the above 2 photon energies became less. The average surface dose of the 15-MV IMRT irradiation increased with the numbermore » of beams in the plan, from 0.86% to 1.19%. Conversely, for 6 MV, the surface dose decreased from 1.33% to 1.24% as the beam number increased from 7 to 9. Comparing the 15-MV FBB and 6-MV IMRT plans with 2 Gy/fraction, the IMRT irradiations gave generally more surface dose, from 15% to 30%, depending on the number of beams in the plan. It was found that the increase in surface dose for the IMRT technique compared to the FBB plan was predominantly due to the number of beams and the calculated monitor units required to deliver the same dose at the isocenter in the plans. The head variation due to the dynamic MLC movement changing the surface dose distribution on the patient was reflected by the IMRT dose-intensity map. Although prostate IMRT in this study had an average higher surface dose than that of FBB, the more even distribution of relatively lower surface dose in IMRT field could avoid the big dose peaks at the surface positions directly under the FBB fields. Such an even and low surface dose distribution surrounding the patient in IMRT is believed to give less skin complication than that of FBB with the same prescribed dose.« less

Authors:
 [1];  [2];  [3];  [2];  [3]
  1. Medical Physics Department, Grand River Regional Cancer Center, Grand River Hospital, Kitchener, Ontario (Canada) and Department of Physics, University of Waterloo, Waterloo, Ontario (Canada). E-mail: james.chow@rmp.uhn.on.ca
  2. Medical Physics Department, Grand River Regional Cancer Center, Grand River Hospital, Kitchener, Ontario (Canada)
  3. (Canada)
Publication Date:
OSTI Identifier:
20858080
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Dosimetry; Journal Volume: 31; Journal Issue: 4; Other Information: DOI: 10.1016/j.meddos.2005.07.002; PII: S0958-3947(06)00049-5; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; COLLIMATORS; COMPUTERIZED TOMOGRAPHY; IRRADIATION; MOSFET; PHANTOMS; PHOTON BEAMS; PHOTONS; PROSTATE; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY; SEMICONDUCTOR MATERIALS; SKIN

Citation Formats

Chow, James, Grigorov, Grigor N., Department of Physics, University of Waterloo, Waterloo, Ontario, Barnett, Rob, and Department of Physics, University of Waterloo, Waterloo, Ontario. Study on surface dose generated in prostate intensity-modulated radiation therapy treatment. United States: N. p., 2006. Web. doi:10.1016/j.meddos.2005.07.002.
Chow, James, Grigorov, Grigor N., Department of Physics, University of Waterloo, Waterloo, Ontario, Barnett, Rob, & Department of Physics, University of Waterloo, Waterloo, Ontario. Study on surface dose generated in prostate intensity-modulated radiation therapy treatment. United States. doi:10.1016/j.meddos.2005.07.002.
Chow, James, Grigorov, Grigor N., Department of Physics, University of Waterloo, Waterloo, Ontario, Barnett, Rob, and Department of Physics, University of Waterloo, Waterloo, Ontario. Sun . "Study on surface dose generated in prostate intensity-modulated radiation therapy treatment". United States. doi:10.1016/j.meddos.2005.07.002.
@article{osti_20858080,
title = {Study on surface dose generated in prostate intensity-modulated radiation therapy treatment},
author = {Chow, James and Grigorov, Grigor N. and Department of Physics, University of Waterloo, Waterloo, Ontario and Barnett, Rob and Department of Physics, University of Waterloo, Waterloo, Ontario},
abstractNote = {The surface doses of 6- and 15-MV prostate intensity-modulated radiation therapy (IMRT) irradiations were measured and compared to those from a 15-MV prostate 4-beam box (FBB). IMRT plans (step-and-shoot technique) using 5, 7, and 9 beams with 6- and 15-MV photon beams were generated from a Pinnacle treatment planning system (version 6) using computed tomography (CT) scans from a Rando Phantom (ICRU Report 48). Metal oxide semiconductor field effect transistor detectors were used and placed on a transverse contour line along the Phantom surface at the central beam axis in the measurement. Our objectives were to investigate: (1) the contribution of the dynamic multileaf collimator (MLC) to the surface dose during the IMRT irradiation; (2) the effects of photon beam energy and number of beams used in the IMRT plan on the surface dose. The results showed that with the same number of beams used in the IMRT plan, the 6-MV irradiation gave more surface dose than that of 15 MV to the phantom. However, when the number of beams in the plan was increased, the surface dose difference between the above 2 photon energies became less. The average surface dose of the 15-MV IMRT irradiation increased with the number of beams in the plan, from 0.86% to 1.19%. Conversely, for 6 MV, the surface dose decreased from 1.33% to 1.24% as the beam number increased from 7 to 9. Comparing the 15-MV FBB and 6-MV IMRT plans with 2 Gy/fraction, the IMRT irradiations gave generally more surface dose, from 15% to 30%, depending on the number of beams in the plan. It was found that the increase in surface dose for the IMRT technique compared to the FBB plan was predominantly due to the number of beams and the calculated monitor units required to deliver the same dose at the isocenter in the plans. The head variation due to the dynamic MLC movement changing the surface dose distribution on the patient was reflected by the IMRT dose-intensity map. Although prostate IMRT in this study had an average higher surface dose than that of FBB, the more even distribution of relatively lower surface dose in IMRT field could avoid the big dose peaks at the surface positions directly under the FBB fields. Such an even and low surface dose distribution surrounding the patient in IMRT is believed to give less skin complication than that of FBB with the same prescribed dose.},
doi = {10.1016/j.meddos.2005.07.002},
journal = {Medical Dosimetry},
number = 4,
volume = 31,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}