Upreti Ritu Raj, Budrukkar Ashwini, Upreti Udita, Misra Shagun, Wadasadawala Tabassum, Kohle Satish, Deshpande Deepak D
Department of Medical Physics, Tata Memorial Hospital, TMC, Parel, Mumbai, India.
Department of Radiation Oncology, Tata Memorial Hospital, TMC, Parel, Mumbai, India.
Brachytherapy. 2017 Sep-Oct;16(5):1028-1034. doi: 10.1016/j.brachy.2017.05.004. Epub 2017 Jun 7.
To investigate the change of clinical target volume (CTV) and its dosimetric impact during the course of accelerated partial breast irradiation (APBI) using intraoperative multicatheter interstitial brachytherapy after open cavity surgery.
Twenty-two patients of APBI with intraoperative placement of catheters underwent computed tomography scans for the treatment planning before the first (CT1) and the last (CT2) treatment fraction. Delineation of lumpectomy cavity and CTV was done consistently on both CT data sets by one of the coauthors. Optimum plan (P) was made on CT1. P was manually reproduced in CT2 which yielded plan P. Plans were compared using coverage index (CI), dose homogeneity index (DHI), external volume index (EI), overdose volume index (OI) and conformal index (COIN).
The mean ± SD volume of lumpectomy cavity and CTV was 78.5 ± 40.7 cm, 156.4 ± 69.0 cm for P, and 84.7 ± 50.1 cm (p = 0.11), 165.7 ± 82.8 cm (p = 0.15) for P, respectively. CTV volume increase by ≥ 10% was observed in 9 cases however decrease of ≥10% was observed in 5 cases. Mean (SD) of absolute pairwise difference in CTV volume was found to be 13.2 (6.7) %. For cases with increase in CTV volume, significant (p < 0.05) decrease of 8.4%, 12.2%, and 5.5% was observed in CI, EI, and COIN of CTV respectively. However for cases with shrinkage of CTV, significant (p = 0.004) increase of 45% in EI was observed, whereas COIN reduced significantly (p = 0.001) by 13.5%. Overall 22 cases showed significant decrease of 5.8% and 8.1% in mean CI and COIN, respectively.
The change of CTV during the course of APBI using intraoperative multicatheter interstitial brachytherapy after open cavity surgery was found patient specific and showed a significant impact on coverage and conformity.
探讨开放性手术后置入多导管组织间插植近距离放疗进行加速部分乳腺照射（APBI）过程中临床靶区（CTV）的变化及其剂量学影响。
22例行APBI且术中置入导管的患者在首次（CT1）和末次（CT2）治疗分次前接受计算机断层扫描以进行治疗计划。由一位共同作者在两个CT数据集上一致地勾画肿块切除腔和CTV。在CT1上制定优化计划（P）。在CT2上手动重现计划P，得到计划P'。使用覆盖指数（CI）、剂量均匀性指数（DHI）、外部体积指数（EI）、过量体积指数（OI）和适形指数（COIN）对计划进行比较。
肿块切除腔和CTV的平均±标准差体积，计划P分别为78.5±40.7cm³、156.4±69.0cm³，计划P'分别为84.7±50.1cm³（p = 0.11）、165.7±82.8cm³（p = 0.15）。9例患者CTV体积增加≥10%，然而5例患者CTV体积减少≥10%。CTV体积的绝对成对差异的平均值（标准差）为13.2（6.7）%。对于CTV体积增加的病例，CTV的CI、EI和COIN分别显著（p < 0.05）下降8.4%、12.2%和5.5%。然而对于CTV缩小的病例，EI显著（p = 0.004）增加45%，而COIN显著（p = 0.001）降低13.5%。总体22例患者的平均CI和COIN分别显著下降5.8%和8.1%。
发现在开放性手术后置入多导管组织间插植近距离放疗进行APBI过程中CTV的变化因患者而异，并且对覆盖范围和适形性有显著影响。
