Gobeli M, Simon A, Getain M, Leseur J, Lahlou E, Lafond C, Dardelet E, Williaume D, Rigaud B, de Crevoisier R
Département de radiothérapie, centre Eugène-Marquis, avenue Bataille-Flandre-Dunkerque, 35000 Rennes, France.
Université de Rennes 1, LTSI, campus de Beaulieu, 35000 Rennes, France; Inserm U1099, campus de Beaulieu, 35000 Rennes, France.
Cancer Radiother. 2015 Oct;19(6-7):471-8. doi: 10.1016/j.canrad.2015.06.010. Epub 2015 Sep 3.
In case of intensity-modulated radiotherapy (IMRT) for locally advanced cervix carcinoma, the objectives were to quantify the difference between the planned and the delivered doses by a standard irradiation, and to estimate the dosimetric benefit of a pretreatment planning library-based adaptive radiotherapy.
Ten patients with locally advanced cervix carcinoma had three planning CTs corresponding to three bladder volumes: empty, intermediate (vi) and full. On each CT, two IMRT plans were generated to deliver 45 Gy to the planning target volume (PTV), with two different margins: clinical target volume (CTV)+10mm and CTV+15 mm. Using bi-weekly CBCTs, three scenarios of treatment have been simulated and compared: standard IMRT (one vi planning) with 10 and 15 mm margins and adaptive radiotherapy with 10mm margin. The cumulated dose in the organs at risk was estimated by elastic registration.
In case of standard IMRT, the cumulated dose was significantly different than the planning dose, with an under-dose of the CTV and the bladder, and an over-dose of the rectum and the peritoneal cavity. For 54% of the fractions, the adaptive radiotherapy planning was not based on vi. Considering the cumulated dose and compared to IMRT with 10-mm margin, adaptive radiotherapy increased the dose to the CTV (1.4 Gy for D98%) and decreased slightly the dose to the rectum and the peritoneal cavity. Compared to a standard IMRT with 15 mm margin, adaptive radiotherapy decreased significantly the dose to the rectum (20% for V40), the bladder (13% for V40) and the peritoneal cavity (2% for V35).
A pretreatment planning library-based adaptive radiotherapy in cervix carcinoma decreases the dose to the organs at risk and increases the dose to the CTV.
对于局部晚期宫颈癌的调强放射治疗（IMRT），目标是量化标准照射下计划剂量与实际 delivered 剂量之间的差异，并评估基于预处理计划库的自适应放射治疗的剂量学益处。
10 例局部晚期宫颈癌患者有对应三个膀胱体积的三个计划 CT：空虚、中间（vi）和充盈。在每个 CT 上，生成两个 IMRT 计划以向计划靶区（PTV）给予 45 Gy，具有两种不同的边界：临床靶区（CTV）+10mm 和 CTV+15mm。使用双周锥形束 CT（CBCT），模拟并比较了三种治疗方案：具有 10mm 和 15mm 边界的标准 IMRT（一个 vi 计划）以及具有 10mm 边界的自适应放射治疗。通过弹性配准估计危及器官的累积剂量。
在标准 IMRT 情况下，累积剂量与计划剂量显著不同，CTV 和膀胱剂量不足，直肠和腹腔剂量过量。对于 54%的分次，自适应放射治疗计划并非基于 vi。考虑累积剂量并与具有 10mm 边界的 IMRT 相比，自适应放射治疗增加了 CTV 的剂量（D98%增加 1.4 Gy），并略微降低了直肠和腹腔的剂量。与具有 15mm 边界的标准 IMRT 相比，自适应放射治疗显著降低了直肠（V40 降低 20%）、膀胱（V40 降低 13%）和腹腔（V35 降低 2%）的剂量。
基于预处理计划库的宫颈癌自适应放射治疗降低了危及器官的剂量并增加了 CTV 的剂量。
