Tomihara Jun, Takatsu Jun, Murakami Naoya, Okonogi Noriyuki, Inoue Tatsuya, Iijima Kotaro, Matsuda Kotaro, Shikama Naoto
Department of Radiation Oncology, Graduate School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan.
Graduate School of Medicine, Nagoya University, Nagoya, Aichi, Japan.
J Appl Clin Med Phys. 2025 Jul;26(7):e70157. doi: 10.1002/acm2.70157.
This study aimed to investigate the effect of inverse planning parameters on dose-volume indices in brachytherapy for uterine cervical cancer.
Fourteen consecutive patients with cervical cancer who received intracavitary and interstitial brachytherapy (IC/ISBT) were selected. Tandem, ovoid, and interstitial needles were used in all cases. The evaluation plans were recalculated from the first fraction of clinical brachytherapy plans. The correlation between the 11 dose optimization parameters of inverse planning and the 13 dose-volume indices was evaluated. The parameters were adjusted in five levels, and dose optimization was performed in hybrid inverse planning optimization (HIPO). Spearman's rank correlation and multiple regression analyses were conducted to assess the association between the parameters and the indices. The indices included clinical target volume (CTV) dose, organ-at-risk (OAR) dose, homogeneity, and conformity. Additionally, the correlation between optimization parameters and calculation time was investigated, along with a technique for efficiently generating treatment plans.
"CTV Max Weight" and "OAR Max Weight" were the key parameters significantly affecting the indices. Increasing "CTV Max Weight" improved homogeneity but reduced the target coverage. The effect of "OAR Max Weight" on the dose reduction of CTV D (β = -0.59) was more significant than that on the dose reduction of OAR D (β = -0.21). In addition, adjusting "CTV Min Weight" and "CTV Volume" could reduce the hyper-dose sleeve without increasing the OAR dose. A large number of normal tissue sampling points could negatively affect the dose distributions and increase the calculation times.
"CTV Max Weight" and "OAR Max Weight" were the most influential parameters in HIPO, significantly affecting dose-volume indices in IC/ISBT for uterine cervical cancer. Additionally, parameters that regulate the hyper-dose sleeve and needle-delivered dose were identified. The quality of treatment planning can be maintained and planning time reduced by appropriately optimizing these parameters.
本研究旨在探讨逆向计划参数对子宫颈癌近距离放射治疗中剂量体积指数的影响。
选取14例接受腔内和组织间插植近距离放射治疗（IC/ISBT）的连续宫颈癌患者。所有病例均使用了施源器、卵圆体和组织间插植针。评估计划从临床近距离放射治疗计划的第一分次重新计算。评估逆向计划的11个剂量优化参数与13个剂量体积指数之间的相关性。参数分五个水平进行调整，并在混合逆向计划优化（HIPO）中进行剂量优化。进行Spearman等级相关分析和多元回归分析，以评估参数与指数之间的关联。这些指数包括临床靶体积（CTV）剂量、危及器官（OAR）剂量、均匀性和适形性。此外，还研究了优化参数与计算时间之间的相关性，以及一种有效生成治疗计划的技术。
“CTV最大权重”和“OAR最大权重”是显著影响指数的关键参数。增加“CTV最大权重”可提高均匀性，但会降低靶区覆盖。“OAR最大权重”对CTV D剂量降低的影响（β = -0.59）比对OAR D剂量降低的影响（β = -0.21）更显著。此外，调整“CTV最小权重”和“CTV体积”可减少高剂量套区，而不增加OAR剂量。大量正常组织采样点会对剂量分布产生负面影响并增加计算时间。
“CTV最大权重”和“OAR最大权重”是HIPO中最具影响力的参数，显著影响子宫颈癌IC/ISBT中的剂量体积指数。此外，还确定了调节高剂量套区和插植针传递剂量的参数。通过适当优化这些参数，可以维持治疗计划质量并减少计划时间。
