Heron D E, Gerszten K, Selvaraj R N, King G C, Sonnik D, Gallion H, Comerci J, Edwards R P, Wu A, Andrade R S, Kalnicki S
University of Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15232, USA.
Gynecol Oncol. 2003 Oct;91(1):39-45. doi: 10.1016/s0090-8258(03)00461-x.
The goals of this study were to evaluate the feasibility of pelvic intensity-modulated radiotherapy (IMRT) in the adjuvant treatment of gynecologic malignancies and to compare the dose-volume histograms (DVHs) and determine the potential impact on acute and long-term toxicity based on the dose to target and nontarget tissues for both planning techniques.
Ten consecutive patients referred for adjuvant radiotherapy for gynecologic malignancies at the University of Pittsburgh School of Medicine and Magee-Womens Hospital were selected for CT-based treatment planning using the ADAC 3D version 4.2g and the NOMOS Corvus IMRT version 4.0. Normal tissues and critical structures were contoured on axial CT slices by both systems in conjunction with a gynecologic radiologist. These regions included internal, external, and common iliac nodal groups, rectum, upper 4 cm of vagina, bladder, and small bowel. Conventional treatment planning included 3D four-field box using 18-MV photons designed to treat a volume from the L(5)/S(1) border superiorly to the bottom of the ischial tuberosity on the AP/PA field and shaped blocks on the lateral fields to minimize the dose to the rectum and small bowel. A seven-field technique using 6-MV photons was used for IMRT. Restraints on small bowel for IMRT were set at 23.0 Gy +/- 5% and 35.0 Gy+/- 5% for the rectum and 37.5 Gy +/- 5% for the bladder while simultaneously delivering full dose (45.0 Gy) to the intrapelvic nodal groups in 1.8-Gy daily fractions. The dose-volume histograms where then compared for both treatment delivery systems.
The volume of each organ of interest (small bowel, bladder, and rectum) receiving doses in excess of 30 Gy was compared in the 3D and IMRT treatment plans. The mean volume of small bowel receiving doses in excess of 30 Gy was reduced by 52% with IMRT compared with 3D. A similar advantage was noted for the rectum (66% reduction) and the bladder (36% reduction). The nodal regions at risk and the upper vagina all received the prescribed dose of 45.0 Gy.
Intensity-modulated radiotherapy appears to offer several advantages over conventional 3D radiotherapy (3D CRT) planning for adjuvant radiotherapy for gynecologic malignancies. These include a significant reduction in treatment volume for bladder, rectum, and small bowel. It is anticipated that this reduction in volume of normal tissue irradiated would translate into overall reduction in acute and potentially late treatment-related toxicity. Prospective trials are necessary to better evaluate the advantages in a larger group of patients.
本研究的目的是评估盆腔调强放射治疗（IMRT）在妇科恶性肿瘤辅助治疗中的可行性，比较剂量体积直方图（DVH），并根据两种计划技术对靶组织和非靶组织的剂量确定其对急性和长期毒性的潜在影响。
连续选取10例在匹兹堡大学医学院和梅杰妇女医院接受妇科恶性肿瘤辅助放疗的患者，使用ADAC 3D版本4.2g和NOMOS Corvus IMRT版本4.0进行基于CT的治疗计划。两个系统均结合妇科放射科医生在轴向CT切片上勾勒出正常组织和关键结构。这些区域包括髂内、髂外和髂总淋巴结组、直肠、阴道上段4 cm、膀胱和小肠。传统治疗计划包括使用18-MV光子的3D四野盒式照射，设计用于在前后野从L5/S1边界向上至坐骨结节底部进行体积照射，并在侧野使用成形挡块以尽量减少对直肠和小肠的剂量。IMRT使用七野技术，使用6-MV光子。IMRT对小肠的限制设定为23.0 Gy±5%，对直肠为35.0 Gy±5%，对膀胱为37.5 Gy±5%，同时以1.8 Gy的每日分次剂量向盆腔内淋巴结组给予全剂量（45.0 Gy）。然后比较两种治疗方案的剂量体积直方图。
在3D和IMRT治疗计划中，比较了接受超过30 Gy剂量的每个感兴趣器官（小肠、膀胱和直肠）的体积。与3D相比，IMRT使接受超过30 Gy剂量的小肠平均体积减少了52%。直肠（减少66%）和膀胱（减少36%）也有类似优势。危险淋巴结区域和阴道上段均接受了规定剂量45.0 Gy。
对于妇科恶性肿瘤的辅助放疗，调强放射治疗似乎比传统的3D放射治疗（3D CRT）计划具有多个优势。这些优势包括膀胱、直肠和小肠的治疗体积显著减少。预计正常组织受照射体积的减少将转化为急性和潜在的晚期治疗相关毒性的总体降低。需要进行前瞻性试验以在更大的患者群体中更好地评估这些优势。
