Repeat CT imaging and replanning during the course of IMRT for head-and-neck cancer
Repeat CT imaging and replanning during the course of IMRT for head-and-neck cancer
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DOI：
10.1016/j.ijrobp.2005.07.957
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发表时间：
2006-02-01
影响因子：
7
通讯作者：
Xia, P
中科院分区：
文献类型：
--
作者：
Hansen, EK;Bucci, MK;Xia, P
目的：许多头颈部（H&N）癌患者在放疗过程中出现肿瘤缩小和/或体重减轻。我们进行了这项回顾性研究，以确定剂量的影响，重复计算机断层扫描（CT）成像和重新规划过程中的调强放疗（IMRT）对正常组织和目标volumes.Methods和材料：一个回顾性的图表审查确定了13例H&N癌症治疗IMRT谁重复CT成像和重新规划过程中的放疗。根据治疗开始前采集的原始计划CT扫描，为每位患者生成第一个IMRT计划。由于放射治疗期间肿瘤缩小或体重减轻，因此进行了第二次CT扫描，并生成了新的计划并用于完成IMRT的过程。使用CT-CT融合来校正扫描之间的患者定位差异。通过使用商业反向IMRT计划系统，通过将第一IMRT计划的射束配置（包括每个射束的强度分布）应用于第二CT扫描的解剖结构，为每个患者生成混合IMRT计划。实际和混合IMRT计划的剂量-体积直方图进行了比较，使用方差分析方法重复measures.Results：所有患者均为局部晚期，非转移性III期或IV期疾病，包括6鼻咽，6口咽，和未知的原发部位。所有患者均接受以铂类为基础的同步化疗。当比较重新计划与不重新计划时，混合调强放射治疗计划（不重新计划）显示出靶体积剂量减少和关键结构剂量增加。在92%的患者中，大体肿瘤体积（PTVGTV）和临床靶体积（PTVCTV）的计划靶体积的95%（D-95）的剂量分别降低了0.8-6.3戈伊（p = 0.02）和0.2-7.4戈伊（p = 0.003）。所有患者脊髓的最大剂量（D-max）均增加（范围，0.2-15.4戈伊; p = 0.003），85%的未重新计划患者的脑干D-max增加（范围：0.6-8.1戈伊; p = 0.007）。在调强放疗过程中对选定的H& N癌症是必不可少的，以确定剂量学的变化，并确保足够的剂量，目标体积和安全剂量的正常组织。未来更大样本量的前瞻性研究将有助于确定接受放射治疗的H&N癌症患者重复CT成像和IMRT重新计划的标准。(C)2006年爱思唯尔公司
Purpose: Many patients with head-and-neck (H&N) cancer have tumor shrinkage and/or weight loss during the course of radiotherapy. We conducted this retrospective study to determine the dosimetric effects of repeat computed tomography (CT) imaging and replanning during the course of intensity-modulated radiotherapy (IMRT) on both normal tissues and target volumes.Methods and Materials: A retrospective chart review identified 13 patients with H&N cancer treated with IMRT who had repeat CT imaging and replanning during the course of radiotherapy. The first IMRT plan for each patient was generated based on the original planning CT scan acquired before the start of treatment. Because of tumor shrinkage or weight loss during radiotherapy, a second CT scan was acquired, and a new plan was generated and used to complete the course of IMRT. CT-CT fusion was used to correct patient positioning differences between the scans. By using a commercial inverse IMRT planning system, a hybrid IMRT plan was generated for each patient by applying the beam configurations of the first IMRT plan (including the intensity profile of each beam) to the anatomy of the second CT scan. The dose-volume histograms of the actual and hybrid IMRT plans were compared using analysis of variance methods for repeated measures.Results: All patients had locally advanced, nonmetastatic Stage III or IV disease, including 6 nasopharynx, 6 oropharynx, and I unknown primary site. All patients were treated with concurrent platinum-based chemotherapy. When replanning vs. not replanning was compared, the hybrid IMRT plans (without replanning) demonstrated reduced doses to target volumes and increased doses to critical structures. The doses to 95% (D-95) of the planning target volumes of the gross tumor volume (PTVGTV) and the clinical target volume (PTVCTV) were reduced in 92% of patients, by 0.8-6.3 Gy (p = 0.02) and 0.2-7.4 Gy (p = 0.003), respectively. The maximum dose (D-max) to the spinal cord increased in all patients (range, 0.2-15.4 Gy; p = 0.003) and the brainstem D-max increased in 85% of patients without replanning (range, 0.6-8.1 Gy; p = 0.007).Conclusions: Repeat CT imaging and replanning during the course of IMRT for selected patients with H&N cancer is essential to identify dosimetric changes and to ensure adequate doses to target volumes and safe doses to normal tissues. Future prospective studies with larger sample sizes will help to determine criteria for repeat CT imaging and IMRT replanning for H&N cancer patients undergoing radiotherapy. (C) 2006 Elsevier Inc.