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Title: SU-E-T-517: Investigation of Factors Contributing to Extracranial Radiation Doses From Leksell Gamma Knife

Abstract

Purpose The purpose of this study is to investigate dominant factors for doses to extracranial sites in treatment with Leksell Gamma Knife (LGK). Methods Monte Carlo simulation was implemented using EGS5 version 1.4.401. The simulation was divided into two major steps for the purpose of efficiency. As the first step, phase-space files were obtained at a scoring plane located just below patient-side surface of the collimator helmet of LGK. Scored particles were classified into three groups, primary, leakage and scatter, using their history information until their arrival to the scoring plane. Then classification was used at the following second step simulation to investigate which type of particle is dominant in the deposited energy at extra-cranial sites. In the second stage, a cylindrical phantom with a semisphere shaped head was modeled such that the geometrical center of the phantom’s head corresponds to the unit center point (UCP) of LGK. Scoring regions were arranged at 10 cm intervals from the UCP to 70 cm away on the central axis of the phantom. Energy deposition from each type of particles and location of interaction were recorded. Results The dominant factor of deposited energy depended on the collimator size. In the case of smallermore » collimator size, leakage was dominant. However, contribution of leakage was relatively small in the case of larger collimator size. The contribution of internal scatter varied with the distance from the UCP. In the proximal areas, internal scatter was dominant, whereas in the distal areas, particles interacting with machine components became dominant factor. Conclusion The Result of this study indicates that the dominant factor to dose to an extracranial site can vary with the distance from UCP and with collimator size. This means that the variation of this contribution must be considered for modeling of the extracranial dose especially in the distal area. This work was partly supported by the JSPS Core-to-Core Program (No. 23003)« less

Authors:
 [1];  [2];  [1]; ; ;  [3]
  1. The University of Tokyo Graduate school of Medicine, Tokyo, JP (Japan)
  2. (Japan)
  3. University of Tokyo Hospital, Tokyo, JP (Japan)
Publication Date:
OSTI Identifier:
22548555
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 42; Journal Issue: 6; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; 61 RADIATION PROTECTION AND DOSIMETRY; COLLIMATORS; COMPUTERIZED SIMULATION; ENERGY ABSORPTION; ENERGY LOSSES; MONTE CARLO METHOD; PARTICLES; PATIENTS; PHANTOMS; PHASE SPACE; RADIATION DOSES; RADIOTHERAPY; SURGERY

Citation Formats

Kon, D, Kameda Medical Centre, Chiba, JP, Nakano, M, Nawa, K, Haga, A, and Nakagawa, K. SU-E-T-517: Investigation of Factors Contributing to Extracranial Radiation Doses From Leksell Gamma Knife. United States: N. p., 2015. Web. doi:10.1118/1.4924879.
Kon, D, Kameda Medical Centre, Chiba, JP, Nakano, M, Nawa, K, Haga, A, & Nakagawa, K. SU-E-T-517: Investigation of Factors Contributing to Extracranial Radiation Doses From Leksell Gamma Knife. United States. doi:10.1118/1.4924879.
Kon, D, Kameda Medical Centre, Chiba, JP, Nakano, M, Nawa, K, Haga, A, and Nakagawa, K. Mon . "SU-E-T-517: Investigation of Factors Contributing to Extracranial Radiation Doses From Leksell Gamma Knife". United States. doi:10.1118/1.4924879.
@article{osti_22548555,
title = {SU-E-T-517: Investigation of Factors Contributing to Extracranial Radiation Doses From Leksell Gamma Knife},
author = {Kon, D and Kameda Medical Centre, Chiba, JP and Nakano, M and Nawa, K and Haga, A and Nakagawa, K},
abstractNote = {Purpose The purpose of this study is to investigate dominant factors for doses to extracranial sites in treatment with Leksell Gamma Knife (LGK). Methods Monte Carlo simulation was implemented using EGS5 version 1.4.401. The simulation was divided into two major steps for the purpose of efficiency. As the first step, phase-space files were obtained at a scoring plane located just below patient-side surface of the collimator helmet of LGK. Scored particles were classified into three groups, primary, leakage and scatter, using their history information until their arrival to the scoring plane. Then classification was used at the following second step simulation to investigate which type of particle is dominant in the deposited energy at extra-cranial sites. In the second stage, a cylindrical phantom with a semisphere shaped head was modeled such that the geometrical center of the phantom’s head corresponds to the unit center point (UCP) of LGK. Scoring regions were arranged at 10 cm intervals from the UCP to 70 cm away on the central axis of the phantom. Energy deposition from each type of particles and location of interaction were recorded. Results The dominant factor of deposited energy depended on the collimator size. In the case of smaller collimator size, leakage was dominant. However, contribution of leakage was relatively small in the case of larger collimator size. The contribution of internal scatter varied with the distance from the UCP. In the proximal areas, internal scatter was dominant, whereas in the distal areas, particles interacting with machine components became dominant factor. Conclusion The Result of this study indicates that the dominant factor to dose to an extracranial site can vary with the distance from UCP and with collimator size. This means that the variation of this contribution must be considered for modeling of the extracranial dose especially in the distal area. This work was partly supported by the JSPS Core-to-Core Program (No. 23003)},
doi = {10.1118/1.4924879},
journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 42,
place = {United States},
year = {2015},
month = {6}
}