Background: Conventional tomotherapy platforms only allow for the delivery of helical IMRT. However the use of IMRT and helical delivery in breast cancer treatment is non-standard. Newer tomotherapy units are equipped...Background: Conventional tomotherapy platforms only allow for the delivery of helical IMRT. However the use of IMRT and helical delivery in breast cancer treatment is non-standard. Newer tomotherapy units are equipped with a static-beam mode with 3DCRT capabilities. During the clinical use, we frequently observe hot-spots in the plan that renders the plan clinically unacceptable. The purpose of this study is to investigate the underlying cause of the hot-spots in tomotherapy static-beam breast treatment and possible solutions. Materials/Methods: Theories about the formation of the hot-spot were developed. Eight lumpectomy patients contoured according to RTOG-1005 specifications were also used to illustrate the magnitude of hot-spots under various planning strategies. Two tangential beams were used for the whole breast irradiation plan with prescription dose of 40 Gy in 15 fractions. Results: The hot-spot was identified as the behavior of the optimization engine when part of the target region was blocked. With the current design of tomotherapy’s 3DCRT planning where user adjustment was greatly limited, none of the planning strategies were able to reduce the hot-spots to acceptable levels in the eight patients studied. The best strategy still produced an average of 48.5 Gy (121% of prescription dose) hot-spot dose and 30.4 cc hot-spot volume (volume receiving > 110% prescription dose). It is also shown that the hot-spot was not a result of energy or other physical limitation of the radiation device. By manually adjusting the plan sinogram, the maximum hot-spot dose drops from 121% to 111% and the hot-spot volume drops from 30 cc to 6 cc on average. Conclusions: While TomoDirect 3DCRT showed great promise in breast treatment, treatment planning software improvements may be needed in order to improve the clinical acceptability by reducing hot-spots in normal tissue.展开更多
目的术中放疗(IORT)和全乳照射(WBI)都是早期乳腺癌患者接受保乳手术时最有效的放疗干预选择,然而,哪项技术能给患者带来更好的肿瘤疗效目前仍存争议。本文meta分析旨在探讨IORT组和WBI组的局部无复发生存期(LRFS)、无远处转移生存期(DM...目的术中放疗(IORT)和全乳照射(WBI)都是早期乳腺癌患者接受保乳手术时最有效的放疗干预选择,然而,哪项技术能给患者带来更好的肿瘤疗效目前仍存争议。本文meta分析旨在探讨IORT组和WBI组的局部无复发生存期(LRFS)、无远处转移生存期(DMFS)和总生存期(OS)的组间差异。方法截至2021年8月1日,我们分别对PubMed、Web of Science、万方、知网、维普五个数据库进行计算机化检索,以纳入符合要求的中、英文发表的临床研究。文献筛选、数据提取和质量评估一式两份。结果一共13篇(13380个患者)纳入了本文meta分析。汇总的结果表明,IORT组的LRFS明显低于WBI组的LRFS(OR=2.36;95%CI,1.66~3.35),而组间的DMFS(OR=0.99;95%CI,0.76~1.29)和OS(OR=0.95;95%CI,0.79~1.14)均无显著统计学差异。结论对于早期乳腺癌患者而言,IORT组的LRFS劣于WBI组的LRFS,而组间的DMFS和OS并无明显差异。展开更多
文摘Background: Conventional tomotherapy platforms only allow for the delivery of helical IMRT. However the use of IMRT and helical delivery in breast cancer treatment is non-standard. Newer tomotherapy units are equipped with a static-beam mode with 3DCRT capabilities. During the clinical use, we frequently observe hot-spots in the plan that renders the plan clinically unacceptable. The purpose of this study is to investigate the underlying cause of the hot-spots in tomotherapy static-beam breast treatment and possible solutions. Materials/Methods: Theories about the formation of the hot-spot were developed. Eight lumpectomy patients contoured according to RTOG-1005 specifications were also used to illustrate the magnitude of hot-spots under various planning strategies. Two tangential beams were used for the whole breast irradiation plan with prescription dose of 40 Gy in 15 fractions. Results: The hot-spot was identified as the behavior of the optimization engine when part of the target region was blocked. With the current design of tomotherapy’s 3DCRT planning where user adjustment was greatly limited, none of the planning strategies were able to reduce the hot-spots to acceptable levels in the eight patients studied. The best strategy still produced an average of 48.5 Gy (121% of prescription dose) hot-spot dose and 30.4 cc hot-spot volume (volume receiving > 110% prescription dose). It is also shown that the hot-spot was not a result of energy or other physical limitation of the radiation device. By manually adjusting the plan sinogram, the maximum hot-spot dose drops from 121% to 111% and the hot-spot volume drops from 30 cc to 6 cc on average. Conclusions: While TomoDirect 3DCRT showed great promise in breast treatment, treatment planning software improvements may be needed in order to improve the clinical acceptability by reducing hot-spots in normal tissue.
文摘目的术中放疗(IORT)和全乳照射(WBI)都是早期乳腺癌患者接受保乳手术时最有效的放疗干预选择,然而,哪项技术能给患者带来更好的肿瘤疗效目前仍存争议。本文meta分析旨在探讨IORT组和WBI组的局部无复发生存期(LRFS)、无远处转移生存期(DMFS)和总生存期(OS)的组间差异。方法截至2021年8月1日,我们分别对PubMed、Web of Science、万方、知网、维普五个数据库进行计算机化检索,以纳入符合要求的中、英文发表的临床研究。文献筛选、数据提取和质量评估一式两份。结果一共13篇(13380个患者)纳入了本文meta分析。汇总的结果表明,IORT组的LRFS明显低于WBI组的LRFS(OR=2.36;95%CI,1.66~3.35),而组间的DMFS(OR=0.99;95%CI,0.76~1.29)和OS(OR=0.95;95%CI,0.79~1.14)均无显著统计学差异。结论对于早期乳腺癌患者而言,IORT组的LRFS劣于WBI组的LRFS,而组间的DMFS和OS并无明显差异。
