van de Schoot Agustinus J A J, de Boer Peter, Visser Jorrit, Stalpers Lukas J A, Rasch Coen R N, Bel Arjan
a Department of Radiation Oncology , Academic Medical Center, University of Amsterdam , Amsterdam , The Netherlands.
Acta Oncol. 2017 May;56(5):667-674. doi: 10.1080/0284186X.2017.1287949. Epub 2017 Feb 20.
Radiation therapy (RT) using a daily plan selection adaptive strategy can be applied to account for interfraction organ motion while limiting organ at risk dose. The aim of this study was to quantify the dosimetric consequences of daily plan selection compared with non-adaptive RT in cervical cancer.
Ten consecutive patients who received pelvic irradiation, planning CTs (full and empty bladder), weekly post-fraction CTs and pre-fraction CBCTs were included. Non-adaptive plans were generated based on the PTV defined using the full bladder planning CT. For the adaptive strategy, multiple PTVs were created based on both planning CTs by ITVs of the primary CTVs (i.e., GTV, cervix, corpus-uterus and upper part of the vagina) and corresponding library plans were generated. Daily CBCTs were rigidly aligned to the full bladder planning CT for plan selection. For daily plan recalculation, selected CTs based on initial similarity were deformably registered to CBCTs. Differences in daily target coverage (D > 95%) and in V, V, V, D and D for rectum, bladder and bowel were assessed.
Non-adaptive RT showed inadequate primary CTV coverage in 17% of the daily fractions. Plan selection compensated for anatomical changes and improved primary CTV coverage significantly (p < 0.01) to 98%. Compared with non-adaptive RT, plan selection decreased the fraction dose to rectum and bowel indicated by significant (p < 0.01) improvements for daily V, V, V, D and D. However, daily plan selection significantly increased the bladder V, V, D and D.
In cervical cancer RT, a non-adaptive strategy led to inadequate target coverage for individual patients. Daily plan selection corrected for day-to-day anatomical variations and resulted in adequate target coverage in all fractions. The dose to bowel and rectum was decreased significantly when applying adaptive RT.
采用每日计划选择自适应策略的放射治疗（RT）可用于考虑分次间器官运动，同时限制危及器官剂量。本研究的目的是量化与宫颈癌非自适应RT相比，每日计划选择的剂量学后果。
纳入连续10例接受盆腔照射的患者，包括计划CT（膀胱充盈和排空）、每周分次后CT和分次前CBCT。基于使用膀胱充盈计划CT定义的PTV生成非自适应计划。对于自适应策略，根据主要CTV（即GTV、宫颈、子宫体和阴道上部）的ITV，基于两个计划CT创建多个PTV，并生成相应的库计划。将每日CBCT刚性配准到膀胱充盈计划CT以进行计划选择。对于每日计划重新计算，基于初始相似度选择的CT与CBCT进行变形配准。评估每日靶区覆盖差异（D＞95%）以及直肠、膀胱和肠道的V、V、V、D和D。
非自适应RT在17%的每日分次中显示对主要CTV覆盖不足。计划选择补偿了解剖学变化，显著提高了主要CTV覆盖率（p＜0.01）至98%。与非自适应RT相比，计划选择降低了直肠和肠道的分次剂量，每日V、V、V、D和D有显著改善（p＜0.01）。然而，每日计划选择显著增加了膀胱的V、V、D和D。
在宫颈癌RT中，非自适应策略导致个体患者靶区覆盖不足。每日计划选择校正了每日解剖学变化，使所有分次的靶区覆盖充足。应用自适应RT时，肠道和直肠的剂量显著降低。
