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2017年4月23日，《中华肿瘤杂志》正式发表山东省肿瘤医院放疗科（国兵、李建彬、王玮、徐敏、邵倩）和物理室（刘同海）的研究报告，探讨了保乳术后基于三维CT（3DCT）和四维CT（4DCT）极限时相定位图像间部分乳腺外照射三维适形放疗计划（3D-CRT）间靶区及危及器官（OAR）剂量体积参数间的差异。 该研究入组20例乳腺癌保乳术后患者，在自由呼吸状态下序贯完成3DCT和4DCT图像扫描，以4DCT的吸气末（EI）时相为基准时相，在EI时相上制订部分乳腺3D-CRT放疗计划，将EI时相的3D-CRT计划复制到呼气末（EE）时相和3DCT图像上，比较3个计划间靶区和OAR相关剂量体积参数的差异。 结果发现：
因此，自由呼吸状态下基于4DCT图像定位，并制订EB-PBI放疗计划在降低危及器官受照剂量方面优于3DCT图像，且基于3DCT图像制订的EB-PBI放疗计划可能会因呼吸运动而产生靶区漏照。 原文参见：中华肿瘤杂志. 2017;39(4):303-307. Zhonghua Zhong Liu Za Zhi. 2017;39(4):303-307. A comparison of dosimetric variance for external-beam partial breast irradiation using three-dimensional and four-dimensional computed tomography. Guo Bing, Li Jianbin, Wang Wei, Xu Min, Shao Qian, Liu Tonghai. Shandong Cancer Hospital, Jinan, China. OBJECTIVE: To investigate the potential dosimetric benefits of four-dimensional computed tomography (4DCT) compared to three-dimensional CT (3DCT) in the planning of radiotherapy for external-beam partial breast irradiation (EB-PBI). METHODS: Three-DCT and 4DCT scan sets were acquired for 20 patients who underwent EB-PBI. For each patient a conventional 3D conformal plan (3D-CRT) was generated based on end-inhalation phase (EI). The treatment plan based on the 4DCT EI phase images was copied and applied to the end-exhalation phase (EE) and 3DCT images (defined as EB-PBIEI, EB-PBIEE, EB-PBI3D, respectively). RESULTS: The median volumes of the tumour bed based on 3DCT, EI and EE were 20.99 cm3, 19.28 cm3, and 18.78 cm3, respectively. The tumour bed volume based on 3DCT was significantly greater than that of EI and EE volumes (P<0.05). The planning target volumes (PTV) coverage of EB-PBI3D, EB-PBIEI and EB-PBIEE were 96.85%, 97.51%, 97.03%, respectively. The planning target volume (PTV) coverage of EB-PBI3D was significantly less than that of EB-PBIEI and EB-PBIEE (P<0.05). The median homogeneity indexs (HI) based on 3DCT, EI and EE were 0.13, 0.13, 0.13, respectively. The median conformal indexs (CI) based on 3DCT, EI and EE were 0.68, 0.69, 0.68, respectively. The median mean doses (Dmean) based on 3DCT, EI and EE were 36.20 Gy, 36.20 Gy, 36.22 Gy, respectively. However there were no significant differences in the homogeneity index, conformity index and the mean dose of PTV between the three treatment plans (P>0.05). The EB-PBI3D plan resulted in the largest organs at risk dose (P<0.05). CONCLUSION: There was a significant benefit when using 4DCT to plan 3D-CRT for EB-PBI with regard to reduced non-target organ exposure, and might result in poor dose coverage when the PTV is determined using 3DCT. KEY WORDS: Breast neoplasms; Radiotherapy planning, computer-assisted; External-beam partial breast irradiation; Three-dimensional computed tomography; Four-dimensional computed tomography; Dosimetrist parameters DOI: 10.3760/cma.j.issn.0253-3766.2017.04.014 |
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