| XIE Jiang,WANG Yun-lai,MA Lin.The effect of ion chamber sensitive volume on absorbed dose measurement accuracy in IMRT dosimetry[J].Chinese Journal of Radiological Medicine and Protection,2007,27(6):582-583 |
| The effect of ion chamber sensitive volume on absorbed dose measurement accuracy in IMRT dosimetry |
| Received:December 02, 2006 |
| DOI： |
| KeyWords:Intensity-modulated radiotherapy Absorbed dose Quality assurance Ion chambers |
| FundProject: |
| Author Name | Affiliation | E-mail | | XIE Jiang | Department of Radiotherapy, PLA General Hospital, Beijing 100853, China | | | WANG Yun-lai | Department of Radiotherapy, PLA General Hospital, Beijing 100853, China | nanyangwang@163.com | | MA Lin | Department of Radiotherapy, PLA General Hospital, Beijing 100853, China | | | 徐寿平 | Department of Radiotherapy, PLA General Hospital, Beijing 100853, China | | | 戴相昆 | Department of Radiotherapy, PLA General Hospital, Beijing 100853, China | |
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| Abstract:: |
| Objective To evaluate the effect of ion chamber sensitive volumes on absorbed dose measurement accuracy in IMRT. Methods A specific patient plan was transferred to digitally reconstructed solid water phantom. Dose points were chosen at isocenter, maximum dose point, uniform dose region and steep dose gradient region for a single field and all beams respectively. Absorbed doses were measured at each point of the phantom with 0.6 cc, 0.125 cc, 0.015 cc ion chambers, and compared with TPS calculated values. Results The measured doses at isocenter and in uniform dose region were less than 5% compared with calculated values for all ion chambers. Large dose errors were found to be 8% at maximum dose point and 12% at steeper dose gradient point for 0.6 cc ion chamber, and small errors were found for 0.015 cc ion chamber. Conclusions 0.6 cc and 0.125 cc ion chambers can be used for dose verifications at small dose gradient points, while at maximum dose point and steeper dose gradient points, 0.015 cc ion chamber is appropriate for absorbed dose verification. |
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