用二维电离室矩阵验证宫颈癌腔内放疗剂量分布  

Dosimetric Verification of the Dose Distribution for a Cervix Intracavity Brachytherapy Using a Tow-dimension Ion Chamber Array

作　　者：刘浩[1,2] 王新[2] 李公平[1] 唐成琼 杜新香[2] 穆塔力普江 马栋辉[2] 王滢[2] 

机构地区：[1]兰州大学核科学与技术学院,甘肃兰州730000 [2]新疆医科大学附属肿瘤医院放疗中心,新疆乌鲁木齐830011

出　　处：《中国医学物理学杂志》2014年第4期4988-4992,共5页Chinese Journal of Medical Physics

基　　金：乌鲁木齐市科技计划项目(Y121310011)

摘　　要：目的:探讨用二维电离室矩阵验证宫颈癌腔内放疗剂量分布。方法:选择6个具有代表性宫颈癌腔内放疗计划,其中治疗长度是5 cm的计划3个,分别使用15°、30°和45°宫腔管,治疗长度是6 cm的计划3个,分别使用15°、30°和45°宫腔管。把15°、30°和45°宫腔管分别夹在固体水等效材料板(SP34)中,用CT(Philips Big Bore)机扫描,获得CT影像,传到后装治疗计划系统(Oncetrol Brachy4.1),在计划系统中标记出宫腔管,再安照病人的腔内治疗计划的设定参数(放射源的驻留位置和驻留时间)布源,计算出剂量分布,把计划传送到后装治疗机的控制计算机上,把1.6 cm厚的固体水和宫腔管施源器放置在二维电离室矩阵(IBA,MATRIXX)面上,执行治疗计划,用MATRIXX进行测量,测量采用Movie模式。然后把该治疗计划的剂量分布导入MATIXX系统的OmniPro I'mRT软件,对比实际测量获得的剂量分布和计划系统计算给出的剂量分布。对比结果用Gamma指数(Δdose<3%,Δd=3 mm)量化。结果:对比实际测量的剂量分布与计划系统给出的剂量分布,发现在每个计划中都存在一个计划计算的剂量平面与实际测量得到的剂量分布的一致性可达到100%(γ≤1),计划计算的剂量平面距宫腔管施源器中心平面的平均距离为(2.3±0.1)cm。结论:宫颈癌腔内放疗计划系统给出的剂量分布与用二维电离室矩阵实测获得的剂量分布一致,用二维电离室矩阵验证宫颈癌腔内放疗剂量分布是一种可行的方法。objective： To verify the dose distribution for a cervix intracavity brachytherapy using a two-dimension ion chamber array in a phantom. Methods： Six cervix intercavity brachytherapy plans were selected to verify the dose distribution, the treatment length of the plans is 5 cm or 6 cm, the catheter of the plans is the intrauterine tube 15°,or the intrauterine tube 30°,or the intrauterine tube 45°. The catheters within the water-equivalent slab （SP34） were scanned with the computed tomography scanner （PHILIPS BIG BORE）and the images of the cathers was exported to the treatment system （TPS）（Oncetrol brachy 4.1 ）. The catheters were marked in the TPS. The dwell position and the dwell time of the Ir-192 brachytherapy radiological source in the catheter were set up as the cervix brachytherapy plan and were exported to the afterloading treatment delivery console computers. The ion chamber arry was irradiated with the plan from the TPS. The thickness of the water equivalent slab between the ion array （IBA, MATRIXX） surface and the catheter is 1.6 cm. The data acquistion in MATRIXX was done in the movie mode.The treatment planning system dose distribution was calculated on the scan of the phantom and was exported to and compared in IBA Dosimetry OmniPro-I＇mRT software. The quality of agreement was quantifyed by the gamma （γ） index （with 3%delta dose anti distance criterion 3 mm） for 6 sets Of plans. Results： For one plan, compareing the measured and TPS caculated distributions,there is only one calculated dose plane agreement with 100% for γ≤ 1 ,the mean distance for 6 sets ofplans between the dose plane and the catheter plane is （2.3±0.1） cm Conclusions： The measured distribution is in agreement with the TPS-caculated distribution.lt is feasible to verify relative dose distriutions for a Cervix Intracavity Brachytherapy.

关 键 词：宫颈癌 腔内后装治疗 剂量验证 

分 类 号：R73[医药卫生—肿瘤]