医用电子直线加速器的性能测量及不同指形电离室对其剂量率的响应特性分析
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摘要
目的:分析医用电子直线加速器的性能测量及不同指形电离室对其剂量率的响应特性分析。方法:选取宝鸡市5家医疗机构正常运行的9台医用加速器(3台国产、6台进口),依照国家标准和职业卫生标准,检测医用电子直线加速器的性能,进行剂量精度及机械性能抽样检测;并选择IBA 0.01 cm3、PTW 0.125 cm3和0.6 cm3的3种不同指形电离室,以100～600 cGy/min剂量范围加速器,在同等机器跳数(MU)与测量条件下,分析不同指形电离室剂量率的响应特性。结果:检测的9台医用加速器检测率为100%;电子线检测中9台医用加速器的穿透特性范畴为-6.54%～5.75%、吸收剂量指示值相对偏差为-9.96%～-2.80%,其合格率分别为66.67%和44.44%,相对较低。X射线检查中,国产医用直线加速器1台灯光野与照射野偏差为3.1 mm,1台吸收剂量指示值相对偏差为4.05%;进口设备1台穿透特性为-9.11%,经调试后3台仪器检测合格率均为100%。在相同能量前提下3种指形电离室中剂量率响应下降幅度最大为IBA 0.01 cm3电离室,6 MV时下降1.60%,15 MV时下降1.40%;PTW 0.125 cm3电离室6 MV时下降0.50%,15 MV时下降0.40%;PTW 0.6 cm3电离室6 MV时下降0.70%,15 MV时下降0.30%。结论:对医用电子直线加速器进行性能测量有助于及时修正剂量偏差;医用电子直线加速器的剂量采集效率会受到剂量仪、不同指形电离室的剂量率与工作电压影响,在剂量测量时应分析、测试设备剂量率,提高仪器精度、检测率及合格率。
Objective: To analyze the performance measurement of medical electron linear accelerator and the response characteristics of different thimble ionization chambers to its dose rate. Methods: 9 medical accelerators of 5 hospitals that included 3 domestics and 6 imports were selected, and their performances were detected and the sampling inspections of precision of dosage and mechanical property were implemented according to national standard and occupational health standards. And three kinds of thimble ionization chambers that included IBA 0.01 cm3, PTW0.125 cm3 and 0.6 cm3 were selected, and the accelerators, which dosage range was from 100 cGy/min to 600 cGy/min, under same MU and measurement conditions were used to analyze the response characteristics of different thimble ionization chambers. Results: The detection rate of 9 medical accelerators was 100%. In electronic line test,the penetration characteristic range of 9 medical accelerators was from-6.54 to 5.75%, and the relative deviation of indication values of absorbed dose was from-9.96% to-2.80%, and the pass rate of them were 66.67% and 44.44%,respectively, which were relatively lower. In the X-ray examination, the deviation of lamplight field and radiation field of 1 domestic accelerator was 1 mm, and the relative deviation of indication value of absorb dose of 1 accelerator was4.05%. The penetration characteristics of one imported equipment was-9.11%, and the test pass rate of 3 equipments was 100% after they were debugged. Under the premise of same energy, the maximum descend range of dosage rate response of 3 thimble ionization chambers was 0.01 cm3 IBA ionization chambers, which decreased 1.60% at 6 MV and decreased 1.40% at 15 MV. The ionization chamber of PTT 0.125 cm3 decreased by 0.50% at 6 MV and decreased by0.40% at 15 MV. The ionization chamber of PTW 0.6 cm3 decreased by 0.70% at 6 MV and decreased by 0.30% at 15 MV. Conclusion: The performance measurement of medical electron linear accelerator is helpful for timely correction of dosage deviation. The collection efficiency of the dosage of medical electron linear accelerator will be affected by the dose rate and working voltage of the dosimeter and different thimble ionization chambers. The dosage rate of equipment should be analyzed and tested when dosage measurement is implemented to improve the accuracy, detection rate and pass rate of equipment.
Objective: To analyze the performance measurement of medical electron linear accelerator and the response characteristics of different thimble ionization chambers to its dose rate. Methods: 9 medical accelerators of 5 hospitals that included 3 domestics and 6 imports were selected, and their performances were detected and the sampling inspections of precision of dosage and mechanical property were implemented according to national standard and occupational health standards. And three kinds of thimble ionization chambers that included IBA 0.01 cm3, PTW0.125 cm3 and 0.6 cm3 were selected, and the accelerators, which dosage range was from 100 cGy/min to 600 cGy/min, under same MU and measurement conditions were used to analyze the response characteristics of different thimble ionization chambers. Results: The detection rate of 9 medical accelerators was 100%. In electronic line test,the penetration characteristic range of 9 medical accelerators was from-6.54 to 5.75%, and the relative deviation of indication values of absorbed dose was from-9.96% to-2.80%, and the pass rate of them were 66.67% and 44.44%,respectively, which were relatively lower. In the X-ray examination, the deviation of lamplight field and radiation field of 1 domestic accelerator was 1 mm, and the relative deviation of indication value of absorb dose of 1 accelerator was4.05%. The penetration characteristics of one imported equipment was-9.11%, and the test pass rate of 3 equipments was 100% after they were debugged. Under the premise of same energy, the maximum descend range of dosage rate response of 3 thimble ionization chambers was 0.01 cm3 IBA ionization chambers, which decreased 1.60% at 6 MV and decreased 1.40% at 15 MV. The ionization chamber of PTT 0.125 cm3 decreased by 0.50% at 6 MV and decreased by0.40% at 15 MV. The ionization chamber of PTW 0.6 cm3 decreased by 0.70% at 6 MV and decreased by 0.30% at 15 MV. Conclusion: The performance measurement of medical electron linear accelerator is helpful for timely correction of dosage deviation. The collection efficiency of the dosage of medical electron linear accelerator will be affected by the dose rate and working voltage of the dosimeter and different thimble ionization chambers. The dosage rate of equipment should be analyzed and tested when dosage measurement is implemented to improve the accuracy, detection rate and pass rate of equipment.
引文
[1]李军,张西志,陈雪梅,等.三种指型电离室对医用直线加速器剂量率的响应特性分析[J].中国医学物理学杂志,2013,30(5):4345-4348.
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[4]翟贺争,程金生,丁艳秋,等.二维电离室矩阵探测器的光子剂量学性能测试[J].中华放射医学与防护杂志,2015,35(2):144-148.
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[11]Nguyen N,Knutson N,Schmidt M,et al.SU-F-P-36:Automation of Linear Accelerator Star Shot Measurement with Advanced XML Scripting and Electronic Portal Imaging Device[J].Med Phys,2016,43(6):3366-3366.
[12]李雪琴,陈栋梁,彭建亮,等.电子直线加速器机房中子辐射屏蔽估算与评价[J].中国职业医学,2014,41(5):518-521.
[13]廖浪,宋瑞英,程鹏.6 Me V医用电子直线加速器中束斑尺寸的计算与测量[J].核技术,2016,39(6):40-45.
[14]康盛伟,黎杰,肖明勇,等.四川省基层放疗单位医用直线加速器剂量和机械性能抽样分析[J].中华放射肿瘤学杂志,2016,25(7):748-751.
[15]Carlone M,Lamey M,Anderson R,et al.MO-F-16A-02:Simulation of a Medical Linear Accelerator for Teaching Purposes[J].Med Phys,2014,41(6Part25):429.
[16]马桥,刘明哲,刘德明,等.某医用加速器性能及放射治疗质量保证系统验证[J].中国辐射卫生,2017,26(1):16-18.
[17]亢锐,张峻峰,肖玉琴.不同方法对医用加速器对称性检定方法的比较[J].中国测试,2015,3(s1):143-145.
[2]Poje M,Ivkovic A,Jurkovic S,et al.The neutron doseequivalentaroundhighenergymedical electron linear accelerators[J].Nuclear Technology and Radiation Protection,2014,29(3):207-212.
[3]韩军,李勤,曹婷,等.四种剂量探测器对放疗加速器常用剂量率的响应特性分析[J].中华放射医学与防护杂志,2012,32(5):527-529.
[4]翟贺争,程金生,丁艳秋,等.二维电离室矩阵探测器的光子剂量学性能测试[J].中华放射医学与防护杂志,2015,35(2):144-148.
[5]卫生部.电子加速器放射治疗放射防护要求:GBZ126-2011[S].卫生部,2011-11-30.
[6]国家质量监督检验检疫总局,中国国家标准化管理委员会.医用电子加速器验收试验和周期检验规程:GB/T 19046-2013[S].北京:中国标准出版社,2014.
[7]国家技术监督局.医用电子加速器性能和试验方法:GB15213-94[S].北京:中国标准出版社,2004.
[8]翁邓胡,徐海荣.高能电子线放射治疗的剂量学参数测量与分析[J].中国医学物理学杂志,2012,29(2):3250-3253.
[9]Tartaglione A,Galván V,Dawidowski J,et al.Design and performance of a compact subthermal neutron source for an Electron Linear Accelerator[J].J Instrumenta,2013,8(11):283-288.
[10]朱卫国,张奇,侯长松,等.医用电子直线加速器治疗室辐射屏蔽计算软件的设计[J].中国医学装备,2014,11(9):34-37.
[11]Nguyen N,Knutson N,Schmidt M,et al.SU-F-P-36:Automation of Linear Accelerator Star Shot Measurement with Advanced XML Scripting and Electronic Portal Imaging Device[J].Med Phys,2016,43(6):3366-3366.
[12]李雪琴,陈栋梁,彭建亮,等.电子直线加速器机房中子辐射屏蔽估算与评价[J].中国职业医学,2014,41(5):518-521.
[13]廖浪,宋瑞英,程鹏.6 Me V医用电子直线加速器中束斑尺寸的计算与测量[J].核技术,2016,39(6):40-45.
[14]康盛伟,黎杰,肖明勇,等.四川省基层放疗单位医用直线加速器剂量和机械性能抽样分析[J].中华放射肿瘤学杂志,2016,25(7):748-751.
[15]Carlone M,Lamey M,Anderson R,et al.MO-F-16A-02:Simulation of a Medical Linear Accelerator for Teaching Purposes[J].Med Phys,2014,41(6Part25):429.
[16]马桥,刘明哲,刘德明,等.某医用加速器性能及放射治疗质量保证系统验证[J].中国辐射卫生,2017,26(1):16-18.
[17]亢锐,张峻峰,肖玉琴.不同方法对医用加速器对称性检定方法的比较[J].中国测试,2015,3(s1):143-145.