Intensity-modulated radiation therapy after hysterectomy: Comparison with conventional treatment and sensitivity of the normal-tissue-sparing effect to margin size
Intensity-modulated radiation therapy after hysterectomy: Comparison with conventional treatment and sensitivity of the normal-tissue-sparing effect to margin size
复制标题
DOI：
10.1016/j.ijrobp.2004.12.029
复制
发表时间：
2005-07-15
影响因子：
7
通讯作者：
Eifel, PJ
中科院分区：
文献类型：
--
作者：
Ahamad, A;D'Souza, W;Eifel, PJ
目的：确定靶体积扩张对子宫切除术后使用调强放疗（IMRT）与标准骨盆适形治疗实现的小肠剂量减少的影响，并探讨患者身体习惯对使用调强放疗（IMRT）实现的正常组织保留的影响。方法和材料：对子宫切除术后接受宫颈癌或子宫内膜癌治疗的患者进行10次计划计算机断层扫描，绘制临床靶体积（CTV）。治疗计划基于阴道ctv和区域淋巴结ctv。考虑到内部运动，增加边缘形成初始规划目标体积（PTVA）如下：在区域节点CTV上增加0.0 mm；阴道CTV前加10 mm；其他各方向阴道CTV均加5mm。另外两个ptv （PTVB和PTVC）由PTVA扩张5mm形成PTVB，再扩张5mm形成PTVC。所有3个PTV的治疗方案都是通过使用2个适形野（2FC）， 4个适形野（4FC）或IMRT来提供45 Gy到97%以上的PTV。IMRT的主要目的是保护小肠。通过比较PTVA、PTVB和PTVC导致的剂量-体积直方图来评估随切缘大小增加而发生的保留变化。测量的患者尺寸与肠保留相关。结果：在剂量大于25 Gy的情况下，IMRT对小肠的照射量明显少于2FC （p < 0.0001）或4FC （p < 0.0001）。IMRT对直肠的照射明显少于2FC （p < 0.0001）或4FC （p < 0.0001）。IMRT对膀胱的照射明显少于2FC （p < 0.0001）。然而，随着切缘的增加，使用IMRT获得的减少幅度减小。特别是，与2FC或4FC相比，IMRT保留的小肠体积随着切缘大小的增加而减少（2FC和4FC分别为p = 0.0002和p = 0.008）。与4FC相比，使用IMRT获得的正常组织保留量与患者体重指数呈负相关。结论：由于使用IMRT实现的小肠保留因靶体积相对较小的扩张而显着减少，因此需要准确的靶区描绘，高度可重复性的患者固定以及清楚地了解内部器官运动，以实现使用IMRT优于传统方法的最佳优势。(c) 2005爱思唯尔公司
Purpose: To determine the influence of target-volume expansion on the reduction in small-bowel dose achieved with use of intensity-modulated radiation therapy (IMRT) vs. standard conformal treatment of the pelvis after hysterectomy, and to investigate the influence of patient body habitus on the normal-tissue sparing achieved with use of IMRT.Methods and Materials: A clinical target volume (CTV) was contoured on each of 10 planning computed tomography scans of patients who had been treated for cervical or endometrial cancer after a hysterectomy. Treatment planning was based on vaginal CTVs and regional nodal CTVs. To account for internal motion, margins were added to form an initial planning target volume (PTVA) as follows: 0.0 mm were added to the regional nodal CTV; 10 mm were added anteriorly to the vaginal CTV; and 5 mm were added to the vaginal CTV in all other directions. Two further PTVs (PTVB and PTVC) were produced by a 5-mm expansion of PTVA to give PTVB and a further 5-mm expansion to give PTVC. Treatment plans for all 3 PTVs were produced by use of 2 conformal fields (2FC), 4 conformal fields (4FC), or IMRT to deliver 45 Gy to more than 97% of the PTV. The primary goal of IMRT was to spare small bowel. The change in sparing that accompanied the increase in margin size was assessed by comparison of dose-volume histograms that resulted from PTVA, PTVB, and PTVC. Measured patient dimensions were correlated with bowel sparing.Results: Significantly less small bowel was irradiated by IMRT than by 2FC (p < 0.0001) or 4FC (p < 0.0001) for doses greater than 25 Gy. Significantly less rectum was irradiated by IMRT than by 2FC (p < 0.0001) or 4FC (p < 0.0001). Significantly less bladder was irradiated by IMRT than by 2FC (p < 0.0001). However, the magnitude of the sparing achieved by use of IMRT decreased as margins increased. In particular, the volume of small bowel spared by IMRT vs. 2FC or 4FC decreased as margin size increased (p = 0.0002 and p = 0.008 for 2FC and 4FC, respectively). The amount of normal-tissue sparing achieved by use of IMRT vs. 4FC was inversely correlated with patient body mass index.Conclusion: Because the small-bowel sparing achieved with use of IMRT is markedly reduced by relatively small expansions of the target volume, accurate target delineation, highly reproducible patient immobilization, and a clear understanding of internal-organ motion are needed to achieve optimal advantage in the use of IMRT over conventional methods of posthysterectomy pelvic radiation therapy. (c) 2005 Elsevier Inc.