中华放射医学与防护杂志
中華放射醫學與防護雜誌
중화방사의학여방호잡지
Chinese Journal of Radiological Medicine and Protection
2012年
4期
412-415
,共4页
指形电离室%光子束%吸收剂量%TRS-277%TRS-398
指形電離室%光子束%吸收劑量%TRS-277%TRS-398
지형전리실%광자속%흡수제량%TRS-277%TRS-398
Cylindrical chambers%Photon beam%Absorbed dose%TRS-277%TRS-398
目的 比较不同指形电离室依据国际原子能机构(IAEA) TRS-277和TRS-398号报告测量高能光子束吸收剂量的差异.方法 针对6种不同型号的指形电离室,依据照射量校准因子Nx分别计算其60Co水吸收剂量校准因子ND,W,Q0,与欧洲标准实验室的测定值比较；依据TRS-277号报告分别计算其水中测量6 MV光子束吸收剂量的射线质修正因子KQ.Q0,与TRS-398号报告给出的值比较；比较其依据TRS-277和TRS-398号报告测量6 MV光子束的吸收剂量实际测量数据.结果 对上述6种指形电离室,依据Nx计算出的ND,W,Q0与欧洲标准实验室直接测定的ND,W.Q0的差异在0.13％～1.30％之间；依据TRS-277号报告计算的kQ.Q0与TRS-398号报告给出的kQ,Q0的差异在0.09％ ～0.45％之间；依据两个报告在水中测量的吸收剂量差异在0.27％～1.40％之间.吸收剂量的主要差异来源于两个报告校准因子Nx和ND,W,Q0的不同.结论 不同指形电离室依据两个报告测量水吸收剂量的差异属于临床可接受的范围,使用TRS-398号报告摆位更方便,计算更简单,测量不确定度降低.
目的 比較不同指形電離室依據國際原子能機構(IAEA) TRS-277和TRS-398號報告測量高能光子束吸收劑量的差異.方法 針對6種不同型號的指形電離室,依據照射量校準因子Nx分彆計算其60Co水吸收劑量校準因子ND,W,Q0,與歐洲標準實驗室的測定值比較；依據TRS-277號報告分彆計算其水中測量6 MV光子束吸收劑量的射線質脩正因子KQ.Q0,與TRS-398號報告給齣的值比較；比較其依據TRS-277和TRS-398號報告測量6 MV光子束的吸收劑量實際測量數據.結果 對上述6種指形電離室,依據Nx計算齣的ND,W,Q0與歐洲標準實驗室直接測定的ND,W.Q0的差異在0.13％～1.30％之間；依據TRS-277號報告計算的kQ.Q0與TRS-398號報告給齣的kQ,Q0的差異在0.09％ ～0.45％之間；依據兩箇報告在水中測量的吸收劑量差異在0.27％～1.40％之間.吸收劑量的主要差異來源于兩箇報告校準因子Nx和ND,W,Q0的不同.結論 不同指形電離室依據兩箇報告測量水吸收劑量的差異屬于臨床可接受的範圍,使用TRS-398號報告襬位更方便,計算更簡單,測量不確定度降低.
목적 비교불동지형전리실의거국제원자능궤구(IAEA) TRS-277화TRS-398호보고측량고능광자속흡수제량적차이.방법 침대6충불동형호적지형전리실,의거조사량교준인자Nx분별계산기60Co수흡수제량교준인자ND,W,Q0,여구주표준실험실적측정치비교；의거TRS-277호보고분별계산기수중측량6 MV광자속흡수제량적사선질수정인자KQ.Q0,여TRS-398호보고급출적치비교；비교기의거TRS-277화TRS-398호보고측량6 MV광자속적흡수제량실제측량수거.결과 대상술6충지형전리실,의거Nx계산출적ND,W,Q0여구주표준실험실직접측정적ND,W.Q0적차이재0.13％～1.30％지간；의거TRS-277호보고계산적kQ.Q0여TRS-398호보고급출적kQ,Q0적차이재0.09％ ～0.45％지간；의거량개보고재수중측량적흡수제량차이재0.27％～1.40％지간.흡수제량적주요차이래원우량개보고교준인자Nx화ND,W,Q0적불동.결론 불동지형전리실의거량개보고측량수흡수제량적차이속우림상가접수적범위,사용TRS-398호보고파위경방편,계산경간단,측량불학정도강저.
Objective To study the difgerence between the IAEA code of practice TRS-Z77 and TRS-398 in the determination of the absorbed dose to water for high-energy photon beams using several cylindrical chambers. Methods For 6 different types of cylindrical chambers,the calibration factors ND,W,Q0 in terms of absorbed dose to water were calculated from the air exposure calibration factors N,,and were compared with the ND,W,Q0 measured in European standard laboratory. Accurate measurements were performed in Varian 6 MV photon beam using 6 cylindrical chambers according to TRS-277 and TRS-398.The beam quality correction factors kQ.Q0 as well as the water absorbed doses were compared.Results For the set of chambers,the difference between ND,W,Q0 computed from Nx and ND.-.Q0 obtained in European standard laboratory was 0.13％ ～ 1.30％.The difference of beam quality correction factors for TRS-277 and TRS-398 was 0.09％ ～0.45％.The distinction of the water absorbed doses obtained according to the two different protocols was 0.27％ ～ 1.40％,and was primarily due to their different calibration factors.Conclusions The discrepancy in absorbed doses determined according to two protocols using different cylindrical chambers is clinically acceptable.However,TRS-398 allows a more convenient localization of chambers,provides a more simple formulation,and offers the reduced uncertainty in the dosimetry of radiotherapy beams.
