| CT扫描电压与CT值-相对电子密度值转换曲线不匹配对放疗计划剂量的影响 |
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| 引用本文： | 孔繁图,陈露茜,金锦辉,董洁,贺亚迪,李政欢.CT扫描电压与CT值-相对电子密度值转换曲线不匹配对放疗计划剂量的影响[J].中国医学物理学杂志,2021,0(3):312-316. |
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| 作者姓名： | 孔繁图 陈露茜 金锦辉 董洁 贺亚迪 李政欢 |
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| 作者单位： | 1.中山大学附属第三医院肿瘤放射治疗科， 广东 广州 510630； 2.南方医科大学生物医学工程学院， 广东 广州 510515 |
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| 摘 要： | 目的:探讨选取不同放疗定位CT扫描电压和CT值-相对电子密度值（CT-RED）转换曲线对放疗计划剂量计算的影响。方法:利用大孔径CT模拟定位机在80、100、120和140 kV电压下对CIRS 062M模体进行扫描，分别建立不同电压下的CT-RED转换曲线；在均匀石蜡模体中心嵌入高密度材料，通过选择不同CT扫描电压与CT-RED转换曲线的组合条件，在计划系统（TPS）设计不同照射角度的放疗计划。分别在高密度材料前、材料中和材料后选取3个兴趣点I1、I2、I3，统计高密度材料的Dmean、D2、D98，分析CT扫描电压与CT-RED转换曲线不匹配时对以上3个兴趣点剂量（DI1、DI2、DI3）和高密度材料Dmean、D2、D98的影响。结果:CT扫描电压与CT-RED转换曲线不匹配的组合条件下，放疗计划剂量有较大差异，其中Dmean、D98、DI2、DI3影响较大，差异具有统计学意义（均P<0.05）。结论:放疗患者CT定位的扫描电压需要与TPS计划设计时选取的CT-RED转换曲线匹配，否则会造成高密度组织中的剂量和射野出口处的剂量计算有较大差异，从而影响放疗计划的准确性。
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| 关 键 词： | CT扫描电压 CT值 相对电子密度 放疗计划 剂量计算 |
Effects of mismatch between CT scanning voltage and CT-RED conversion curve on radiotherapy dose |
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| KONG Fantu,CHEN Luxi,JIN Jinhui,DONG Jie,HE Yadi,LI Zhenghuan.Effects of mismatch between CT scanning voltage and CT-RED conversion curve on radiotherapy dose[J].Chinese Journal of Medical Physics,2021,0(3):312-316. |
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| Authors: | KONG Fantu CHEN Luxi JIN Jinhui DONG Jie HE Yadi LI Zhenghuan |
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| Affiliation: | 1. Department of Radiation Oncology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510630, China 2.School of Biomedical Engineering, South Medical University, Guangzhou 510515, China |
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| Abstract: | Objective To explore the effects of different voltages selected for computed tomography(CT)positioning and CT number-relative electron density(CT-RED)conversion curves on the calculation of radiotherapy dose.Methods Under the voltages of 80,100,120 and 140 kV,CIRS 062M phantom were scanned by a large-aperture CT simulator,thereby establishing CT-RED conversion curves under different voltages.A known high-density material was embedded in the center of a uniform paraffin phantom,and by setting a series of combinations of different voltages and CT-RED conversion curves,radiotherapy plans with different irradiation angles were established in treatment planning system.The variations of doses(DI1,DI2 and DI3)delivered to 3 points of interest(I1,I2 and I3)selected at the front,middle and rear of the high-density material and the changes in the Dmean,D2 and D98 of the high-density material were analyzed when voltages mismatched with CT-RED conversion curves.Results Under the mismatch between voltages and CT-RED conversion curves,the doses of radiotherapy plan were significantly different,among which Dmean,D98,DI2,DI3 were most affected,with statistical differences(all P<0.05).Conclusion The voltage for CT positioning needs to match with CT-RED conversion curve selected for radiotherapy planning.Otherwise,it will lead to great differences in the calculations of dose in the high-density material and the dose at the exit of radiation field,thus affecting radiotherapy accuracy. |
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| Keywords: | CT scanning voltage CT number relative electron density radiotherapy plan dose calculation |
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