机载千伏级锥形束CT影像引导下危及器官剂量测定方法研究  

Study on measured method of the OAR dose under the guidance of kV-CBCT images

作　　者：高李欣 岳海振 姜晓燕[1] 张震 丁库克[3] GAO Li-xin;YUE Haizhen;JIANG Xiao-yan(Department of Radioecology,National Institute for Radiological Protection,China CDC,Beijing 100088,China;不详)

机构地区：[1]中国疾病预防控制中心辐射防护与核安全医学所放射生态学研究室,北京100032 [2]国家卫生健康委职业安全卫生研究中心职业卫生(放射卫生)监测与评价室,北京102308 [3]中国疾病预防控制中心公共卫生管理处,北京102200

出　　处：《中国医学装备》2023年第3期11-15,共5页China Medical Equipment

基　　金：北京市自然科学基金资助课题(1202009)“非匀速运动机架到位精度对容积调强放疗的剂量学影响评价及临床决策研究”。

摘　　要：目的:采用瓦里安加速器机载千伏级锥形束CT(kV-CBCT)对模体进行标准胸部扫描,测量不同次数影像引导下的胸部肿瘤周围危及器官(OAR)的吸收剂量,从而评估患者在整个放射治疗期间影像引导所致的OAR吸收剂量。方法:选用一致性≤±2%的热释光剂量计(TLD)并在标准剂量实验室刻度,将其放置在Anderson Rando模体的预留插孔内,在kVCBCT标准胸部扫描条件下,测量OAR在单次和5次影像引导下的吸收剂量,并以此计算器官当量剂量。结果:单次kVCBCT扫描条件下照射野内器官的吸收剂量范围在0.519~3.915 mGy,5次kV-CBCT扫描条件下照射野内器官的吸收剂量范围在1.436~17.971 mGy。其中心脏的吸收剂量最高,单次kV-CBCT扫描下的吸收剂量为3.915 mGy,5次kV-CBCT扫描下的吸收剂量为17.971 mGy;甲状腺右侧叶的吸收剂量最低,单次kV-CBCT扫描下的吸收剂量为0.519 mGy,5次kVCBCT扫描下的吸收剂量为1.436 mGy。感兴趣器官中左肺、右肺、心脏、甲状腺左侧、甲状腺右侧、左乳腺和右乳腺在不同辐照次数之间,TLD信号值的差异有统计学意义(Z=-12.120,Z=-10.574,Z=-39.202,Z=-5.716,Z=-13.483,Z=-20.838,Z=-42.698;P<0.05)。结论:多次影像引导条件下,OAR的累积吸收剂量不可采用单次剂量与影像引导次数的乘积计算,kV-CBCT影像引导下OAR剂量测定方法可为放射治疗患者在影像引导期间OAR累积吸收剂量的计算提供理论依据。Objective:To measure the absorbed dose of organ at risk(OAR)around thoracic cancer under the guidance of images of different times by using the kilovoltage cone-beam CT(kV-CBCT)on the Varian linear accelerator to conduct standard scan on chest of phantom,so as to assess the OAR absorbed dose caused by guidance of image of patients during the whole radiotherapy.Methods:The thermoluminescence dosimeters(TLDs)which consistencies were within±2%were selected,and they were calibrated in the standard dose laboratory.And then,under the kV–CBCT scan condition of chest,they were placed in the reserved jack of the Anderson Rando phantom to measure the absorbed dose of OAR under the guidance of the single time and 5 times of images,and the equivalent dose of the organ was calculated.Results:The range of absorbed dose of the organ within exposure field was 0.519-3.915 under single kV-CBCT scan condition,and that was 1.436-17.971 under 5 times of kV-CBCT scan condition.Among of them,the absorbed dose of heart was highest,which absorbed dose was 3.915mGy under single time of kV-CBCT scan,and which absorbed dose was 17.971mGy under 5 times of kV-CBCT scan.The absorbed dose of right side of the leaf of thyroid was the lowest,which absorbed dose was 0.519mGy under single time of kV-CBCT scan,and which absorbed dose was 1.436mGy under 5 times of kV-CBCT scan.The differences of TLD signal values of the interesting organs,which included left lung,right lung,heart,the left and right sides of thyroid,and the left and right sides of mammary gland,among different times of radiation were significant(Z=-12.120,Z=-10.574,Z=-39.202,Z=-5.716,Z=-13.483,Z=-20.838,Z=-42.698,P<0.05),respectively.Conclusion:Under the guided condition with multiple-times image,the OAR absorbed dose of accumulation cannot adopt the product calculation of single time of dose and the guided times of image.The measured method of OAR dose under the guidance of kV-CBCT image can provide theoretical basis for the calculation of OAR absorbed dose of accumulation of pati

关 键 词：热释光剂量计(TLD) 千伏级锥形束CT(kV-CBCT) 影像引导放射治疗 危及器官(OAR) 

分 类 号：R814.2[医药卫生—影像医学与核医学]