Megavoltage Photon Beam Attenuation by Carbon Fiber Couch Tops and its Prediction Using Correction Factors
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- HAYASHI Naoki
- Faculty of Radiological Technology, School of Health Science, Fujita Health University Department of Radiology, Nagoya City University Graduate School of Medical Sciences
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- SHIBAMOTO Yuta
- Department of Radiology, Nagoya City University Graduate School of Medical Sciences
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- OBATA Yasunori
- Graduate school of Medicine, Nagoya University
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- KIMURA Takashi
- Nagoya Radiosurgery Center, Nagoya Kyoritsu Hospital
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- NAKAZAWA Hisato
- Nagoya Radiosurgery Center, Nagoya Kyoritsu Hospital
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- HAGIWARA Masahiro
- Nagoya Radiosurgery Center, Nagoya Kyoritsu Hospital
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- HASHIZUME Chisa I.
- Nagoya Radiosurgery Center, Nagoya Kyoritsu Hospital
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- MORI Yoshimasa
- Nagoya Radiosurgery Center, Nagoya Kyoritsu Hospital
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- KOBAYASHI Tatsuya
- Nagoya Radiosurgery Center, Nagoya Kyoritsu Hospital
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抄録
The purpose of this study was to evaluate the effect of megavoltage photon beam attenuation (PBA) by couch tops and to propose a method for correction of PBA. Four series of phantom measurements were carried out. First, PBA by the exact couch top (ECT, Varian) and Imaging Couch Top (ICT, BrainLAB) was evaluated using a water-equivalent phantom. Second, PBA by Type-S system (Med-Tec), ECT and ICT was compared with a spherical phantom. Third, percentage depth dose (PDD) after passing through ICT was measured to compare with control data of PDD. Forth, the gantry angle dependency of PBA by ICT was evaluated. Then, an equation for PBA correction was elaborated and correction factors for PBA at isocenter were obtained. Finally, this method was applied to a patient with hepatoma. PBA of perpendicular beams by ICT was 4.7% on average. With the increase in field size, the measured values became higher. PBA by ICT was greater than that by Type-S system and ECT. PBA increased significantly as the angle of incidence increased, ranging from 4.3% at 180° to 11.2% at 120°. Calculated doses obtained by the equation and correction factors agreed quite well with the measured doses between 120° and 180° of angles of incidence. Also in the patient, PBA by ICT was corrected quite well by the equation and correction factors. In conclusion, PBA and its gantry angle dependency by ICT were observed. This simple method using the equation and correction factors appeared useful to correct the isocenter dose when the PBA effect cannot be corrected by a treatment planning system.
収録刊行物
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- Journal of Radiation Research
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Journal of Radiation Research 51 (4), 455-463, 2010
Journal of Radiation Research 編集委員会
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詳細情報 詳細情報について
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- CRID
- 1390001205215860480
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- NII論文ID
- 10026564021
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- NII書誌ID
- AA00705792
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- ISSN
- 13499157
- 04493060
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- NDL書誌ID
- 10766151
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- 本文言語コード
- en
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- データソース種別
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- JaLC
- NDL
- Crossref
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可