Tomotherapy计划系统中利用不同密度模体精确创建CT值密度曲线  

Method of Creating Image Value to Density Table by Different Brand Density Phantoms in Tomotherapy Treatment Planning System

作　　者：庞廷田[1] 杨波[1] 于浪[1] 刘峡[1] 刘楠[1] 李文博[1] 董婷婷[1] 邱杰[1] PANG Tingtian;YANG Bo;YU Lang;LIU Xia;LIU Nan;LI Wenbo;DONG Tingting;QIU Jie(Department of Radiotherapy,Peking Union Medical College Hospital,Beijing 100730,China)

机构地区：[1]北京协和医院放疗科,北京100730

出　　处：《中国医疗设备》2022年第2期29-34,共6页China Medical Devices

基　　金：“十三五”国家重点研发计划(2016YFC0105206;2016YFC0105207)。

摘　　要：目的通过研究不同密度模体创建的CT值密度曲线(Image Value to Density Table,IVDT)对剂量计算精度的影响,探讨如何在Tomotherapy计划系统中正确创建IVDT。方法分别用Gammex和CIRS两种密度模体创建立应的IVDT表,其中以是否含有空气密度点和在CT值-100~100 HU范围内是否包含除水以外的物质密度点分别创建IVDT表。调用不同IVDT表设计4组调强计划,同时生成7组剂量传输验证计划(Delivery Quality Assurance,DQA),测量上述11组调强计划的剂量偏差并进行配对t检验判断IVDT表是否符合要求。结果IVDT表中含有-100~100 HU计划组剂量偏差为1.55%±0.9%,与标准计划组剂量偏差比,有统计学差异(P<0.01),同理,不含空气密度点组的剂量偏差也有明显剂量学差异。7组DQA计划中调用CIRS IVDT Abdo(-100~100 HU)、Gammex IVDT Abdo(standard)的5组DQA计划剂量偏差,无统计学差异(P>0.05);调用CIRS IVDT Abdo(-100~100 HU)的2组DQA计划平均剂量偏差均为1.77%±1%,与对照组剂量偏差相比,有统计学差异。结论创建IVDT表时需要确保CT值在-100~100 HU范围内除水以外不含任何其他物质密度点,同时曲线中应该加入空气密度点,此两点对剂量计算精度影响较大。Objective By studying the effect of Image Value to Density tables(IVDT)created by different brand density phantoms on Tomotherapy dose calculation accuracy,to explore how to create IVDT correctly in a Tomotherapy planning system.Methods The corresponding IVDT tables were established by Gammex and CIRS density models respectively.The IVDT tables were created by whether there were density points of air and whether there were density points of substances other than water in the range of CT value-100~100 HU.Four groups of intensity modulation plans were designed using different IVDT tables,and seven groups of delivery quality assurance(DQA)were generated at the same time.Dose deviations of the 11 groups of intensity modulation plans were measured and paired T test was performed to determine whether the IVDT table met the requirements.Results In the IVDT table,the dose deviation of the-100~100 HU plan group was 1.55%±0.9%,which was statistically different from that of the standard plan group(P<0.01).Similarly,the dose deviation of the group without air density point also showed significant dosiological difference.There was no significant difference in the dose deviation of the 5 groups of DQA plan using CIRS IVDT Abdo(-100~100 HU)and Gammex IVDT Abdo(Standard)in 7 groups(P>0.05).The mean dose deviation of DQA plan in the two groups using CIRS IVDT Abdo(-100~100 HU)was 1.77%±1%,which was statistically different from that in the control group.Conclusion When creating the IVDT table,it is necessary to ensure that CT values within the range of-100~100 HU do not contain any density points of other substances except water,and air density points should be added into the curve,which have a great influence on the accuracy of dose calculation.

关 键 词：tomotherapy计划治疗系统 CT值密度曲线 剂量传输验证计划 剂量偏差 

分 类 号：R318.6[医药卫生—生物医学工程] TH774[医药卫生—基础医学]