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Experimental verification of dose calculation using the simplified Monte Carlo method with an improved initial beam model for a beam-wobbling system
https://repo.qst.go.jp/records/46902
https://repo.qst.go.jp/records/469020d7a49d8-0d4a-43ae-a766-9225d6e51e70
| Item type | 学術雑誌論文 / Journal Article(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2014-11-06 | |||||
| タイトル | ||||||
| タイトル | Experimental verification of dose calculation using the simplified Monte Carlo method with an improved initial beam model for a beam-wobbling system | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||
| 資源タイプ | journal article | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Tansho, Ryohei
× Tansho, Ryohei× Takada, Yoshihisa× Kohno, Ryosuke× Hotta, Kenji× Hara, Yousuke× et.al× 丹正 亮平× 高田 義久× 原 洋介 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | A beam delivery system using a single-radius-beam-wobbling method has been used to form a conformal irradiation field for proton radiotherapy in Japan. A proton beam broadened by the beam-wobbling system provides a non-Gaussian distribution of projection angle different in two mutually orthogonal planes with a common beam central axis, at a certain position. However, the conventional initial beam model for dose calculations has been using an approximation of symmetric Gaussian angular distribution with the same variance in both planes (called here a Gaussian model with symmetric variance (GMSV)), instead of the accurate one. We have developed a more accurate initial beam model defined as a non-Gaussian model with asymmetric variance (NonGMAV), and applied it to dose calculations using the simplified Monte Carlo (SMC) method. The initial beam model takes into account the different distances of two beam-wobbling magnets from the iso-center and also the different amplitudes of kick angle given by each magnet. We have confirmed that the calculation using the SMC with NonGMAV reproduced the measured dose distribution formed in air by a mono-energetic proton beam passing through a square aperture collimator better than with the GMSV and with a Gaussian model with asymmetric variance (GMAV) in which different variances of angular distributions are used in the two mutually orthogonal planes. Measured dose distributions in a homogeneous phantom formed by a modulated proton beam passing through a range shifter and an L-shaped range compensator, were consistent with calculations using the SMC with GMAV and NonGMAV, but in disagreement with calculations using the SMC with GMSV. Measured lateral penumbrae in a lateral direction were reproduced better by calculations using the SMC with NonGMAV than by those with GMAV, when an aperture collimator with a smaller opening was used. We found that such a difference can be attributed to the non-Gaussian angular distribution of the initial beam at a lateral position for the beam-wobbling system. Calculations using the SMC with NonGMAV are effective to reproduce dose distributions formed by a beam-wobbling system more accurately than that with GMSV or that with GMAV. |
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| 書誌情報 |
PHYSICS IN MEDICINE AND BIOLOGY 巻 58, 号 17, p. 6047-6064, 発行日 2013-09 |
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| 出版者 | ||||||
| 出版者 | IOP Publishing | |||||
| ISSN | ||||||
| 収録物識別子タイプ | ISSN | |||||
| 収録物識別子 | 0031-9155 | |||||
| DOI | ||||||
| 識別子タイプ | DOI | |||||
| 関連識別子 | 10.1088/0031-9155/58/17/6047 | |||||
| 関連サイト | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | http://iopscience.iop.org/0031-9155/58/17/6047/article | |||||
| 関連名称 | http://iopscience.iop.org/0031-9155/58/17/6047/article | |||||
