Division of Radiation Oncology, City of Hope Medical Center, Duarte, CA, USA.
Int J Radiat Oncol Biol Phys. 2012 Sep 1;84(1):289-95. doi: 10.1016/j.ijrobp.2011.10.068. Epub 2012 Jan 26.
To define setup variations in the radiation treatment (RT) of anal cancer and to report the advantages of image-guided RT (IGRT) in terms of reduction of target volume and treatment-related side effects.
Twelve consecutive patients with anal cancer treated by combined chemoradiation by use of helical tomotherapy from March 2007 to November 2008 were selected. With patients immobilized and positioned in place, megavoltage computed tomography (MVCT) scans were performed before each treatment and were automatically registered to planning CT scans. Patients were shifted per the registration data and treated. A total of 365 MVCT scans were analyzed. The primary site received a median dose of 55 Gy. To evaluate the potential dosimetric advantage(s) of IGRT, cases were replanned according to Radiation Therapy Oncology Group 0529, with and without adding recommended setup variations from the current study.
Significant setup variations were observed throughout the course of RT. The standard deviations for systematic setup correction in the anterior-posterior (AP), lateral, and superior-inferior (SI) directions and roll rotation were 1.1, 3.6, and 3.2 mm, and 0.3°, respectively. The average random setup variations were 3.8, 5.5, and 2.9 mm, and 0.5°, respectively. Without daily IGRT, margins of 4.9, 11.1, and 8.5 mm in the AP, lateral, and SI directions would have been needed to ensure that the planning target volume (PTV) received ≥95% of the prescribed dose. Conversely, daily IGRT required no extra margins on PTV and resulted in a significant reduction of V15 and V45 of intestine and V10 of pelvic bone marrow. Favorable toxicities were observed, except for acute hematologic toxicity.
Daily MVCT scans before each treatment can effectively detect setup variations and thereby reduce PTV margins in the treatment of anal cancer. The use of concurrent chemotherapy and IGRT provided favorable toxicities, except for acute hematologic toxicity.
定义放射治疗（RT）中肛门癌的摆位变化，并报告图像引导 RT（IGRT）在减少靶区和治疗相关副作用方面的优势。
选择了 2007 年 3 月至 2008 年 11 月期间，12 例连续接受螺旋断层放疗联合放化疗的肛门癌患者。在对患者进行固定和定位后，在每次治疗前进行兆伏计算机断层扫描（MVCT）扫描，并自动将其与计划 CT 扫描进行配准。根据配准数据对患者进行移位并进行治疗。共分析了 365 次 MVCT 扫描。原发部位接受的中位数剂量为 55 Gy。为了评估 IGRT 的潜在剂量学优势，根据放射治疗肿瘤学组 0529 对病例进行了重新计划，并根据当前研究添加了建议的摆位变化。
在整个 RT 过程中观察到明显的摆位变化。前-后（AP）、侧和上-下（SI）方向和滚转的系统摆位校正的标准差分别为 1.1、3.6 和 3.2 mm，以及 0.3°。平均随机摆位变化分别为 3.8、5.5 和 2.9 mm，以及 0.5°。如果没有每日 IGRT，AP、侧和 SI 方向的 PTV 为确保接受≥95%的规定剂量，需要 4.9、11.1 和 8.5 mm 的边缘。相反，每日 IGRT 不需要 PTV 的额外边缘，并导致肠 V15 和 V45 以及骨盆骨髓 V10 的显著减少。观察到有利的毒性，除了急性血液学毒性。
在每次治疗前进行每日 MVCT 扫描可以有效地检测摆位变化，从而减少肛门癌治疗中的 PTV 边缘。同时使用化疗和 IGRT 提供了有利的毒性，除了急性血液学毒性。
