应用密度填充及伪影消减技术提高带金属植入物患者IMRT剂量准确度研究  

Study of improving IMRT dose accuracy in patients with metal implants by density filling and artifact reduction

作　　者：赵培峰[1] 周钢[1] 孙彦泽[1] 杨咏强[1] 邢鹏飞[1] Zhao Peifeng;Zhou Gang;Sun Yanze;Yang Yongqiang;Xing Pengfei(Department of Radiotherapy Oncology,The Second Affiliated Hospital of Soochow University,Institute of Radiotherapy Oncology,Soochow University,Suzhou Key Laboratory for Radiation Oncology,Suzhou 2150074,China)

机构地区：[1]苏州大学附属第二医院放疗科,苏州大学放射肿瘤治疗学研究所,苏州市肿瘤放射治疗重点实验室,215004

出　　处：《中华放射肿瘤学杂志》2020年第5期378-382,共5页Chinese Journal of Radiation Oncology

基　　金：江苏省医学创新团队(CXDT-37);苏州市科技发展计划项目(SS201642)。

摘　　要：目的探讨提高带金属植入物患者放射治疗计划剂量计算准确度的方法。方法利用具有金属伪影消减技术的CT模拟机对插入金属棒的CIRS调强模体和8例椎体中植入了钢钉并接受放疗的患者进行扫描,在获得的常规CT图像、金属伪影消减技术CT图像及对其金属区域进行密度填充的图像上设计治疗计划。在模体中比较单个射野及IMRT计划的计算结果与剂量测量结果,同时对患者IMRT计划中金属植入物及其伪影对照射剂量产生的影响进行分析。结果基于常规CT图像的放疗计划中,射野入射路径未通过金属区域时,单个射野的剂量计算误差为3.85%,通过金属区域时射野计算误差范围达4.46%~74.11%。IMRT计划中存在入射路径通过金属区域的射野时,其误差可能超出临床可接受的范围,计算误差随这种射野所占剂量权重的增加而变大。当采用密度填充及伪影消减技术处理图像后,上述单个射野的计算误差分别为1.23%和0.89%~4.73%,IMRT计划的剂量误差为1.84%。若单独采用密度填充技术处理金属区域,IMRT计划的剂量误差为1.88%。基于常规CT图像的患者IMRT计划中,受金属植入物及其伪影的影响,实际靶区受到的最小剂量、平均剂量及处方剂量覆盖率较计划结果下降,危及器官剂量相近。结论基于常规CT图像的放疗计划中,入射路径通过金属区域的射野可能产生较大的剂量计算误差。如果植入的金属材料已知,在计划系统中对金属区域进行密度填充能有效提高计划的剂量计算准确度。伪影消减技术能显著改善图像质量,进一步减少剂量计算误差,对于配备这种功能的CT机进行带金属植入物患者的模拟定位时应作为常规技术。Objective To explore the method of improving the accuracy of dose calculation of treatment plan in radiotherapy for patients with metal implants.Methods A CT simulator with metal artifact reduction technique(MAR)was utilized to scan the CIRS intensity-modulated phantom with metal rods and 8 patients with steel nails implanted in the centrum for radiotherapy.Radiotherapy plans were designed using conventional CT images,MAR images and density-filled images.The dose calculation errors between single field and intensity-modulated radiotherapy(IMRT)plan were compared.The effect of mental implants and their artifacts on the irradiation dose of IMRT plan was evaluated.Results In the conventional CT images of the phantom,when the incident path of the field failed to pass through the metal region,the dose calculation error for a single field was 3.85%,and the range of dose error for the field was 4.46%-74.11%when passing through the metal region.IMRT planning errors might exceed the clinically acceptable range when the incident path of the field passed through the metal region,and the errors tended to increase with the increase of dose weight of this field.After processing the images with density filling and artifact reduction techniques,the errors of the single field were 1.23%and 0.89%-4.73%,respectively,and the dose error of IMRT was 1.84%.The error of IMRT plan was 1.88%if density filling technique alone was employed to process the metal region.Due to the influence of metal implants and their artifacts,the minimum dose,average dose and prescription dose coverage actually received in the tumor target area were lower than IMRT plan results based on conventional CT images.The dosimetric difference of organs at risk was not statistically significant.Conclusions In the radiotherapy plan based on conventional CT images,there may be a large dose calculation error when the incident path of field passes through the metal region.If the metal material is known,density filling of the metal region in the planning system can effect

关 键 词：金属植入物 调强放射治疗 剂量计算 准确度 

分 类 号：R730[医药卫生—肿瘤]