Set-up error in supine-positioned patients immobilized with two different modalities during conformal radiotherapy of prostate cancer
Set-up error in supine-positioned patients immobilized with two different modalities during conformal radiotherapy of prostate cancer
复制标题
DOI：
10.1016/s0167-8140(98)00127-3
复制
发表时间：
1998-11-01
影响因子：
5.7
通讯作者：
Calandrino, R
中科院分区：
文献类型：
--
作者：
Fiorino, C;Reni, M;Calandrino, R
背景：与传统放射治疗技术相比，适形放射治疗需要减少临床靶区周围的边缘。目的：探讨两种不同固定技术在前列腺癌小野适形放射治疗中的效果。材料与方法：1996年11月至1998年3月，52例前列腺癌患者接受根治性或辅助性保形三握或四握固定。总共，每周收集539张门脉图像，至少在治疗的前4周内对侧方和前方的IS MV X线场进行检查。每个患者监测的平均疗程数为5.7次(范围4-10次)。所有患者均采用α-摇篮系统固定，其中骨盆水平固定25例(A组)，小腿固定27例(B组)。通过测量相同的骨骼地标和保持的边缘之间的距离来评估相对于模拟条件的移位。考虑了颅尾(CC)、前后(PA)和左右(LR)移位的整体分布；对每个患者，按照Bijhold等人建议的程序评估了随机和系统性误差分量。(Bijhold J，Lebesque JV，Hart AAM，VijlBrief RE.将应用于前列腺癌的适形增强技术的门脉图像用于最大化设置精度。辐射体。奥科尔。1992年；24：261-271)。结果：B组PA移位(2.6 mm比4.4 mm，1 SD)、LR移位(2.4 mm比3.6 mm，1 SD)和CC移位(2.7 mm比3.3 mm，1 SD)的准确性和重复性均优于A组。此外，与A组的21.6%(P<；0.0001)相比，B组的PA大移位率(>；5 mm)为4.4%。这一值也好于先前调查的21名未固定患者(Italia C、Fiorino C、Ciocca M等)的对应值。前列腺癌适形放射治疗的门脉胶片分析质量控制：两种不同机构和治疗技术的比较(摘要)。辐射体。奥科尔。1997年；43(补充2)：S16，16.8%，P=0.001)。对于这两组人来说，其中一种成分(系统的或随机的)相对于另一种成分没有明显的流行率。B组平均等中心移位3.0 mm(+/-1.4 mm，ISD)，A组5.0 mm(+/-2.8 mm，1SD)，而未固定组平均等中心移位4.4 mm(+/-2.4 mm，ISD)。结论：α-摇篮系统固定双腿似乎提高了前列腺癌患者盆腹固定的准确性和可重复性。基于这些数据，我们决定使用腿部固定系统，并在PA方向上减少CTV周围的边缘(从10毫米减少到8毫米)。(C)1998爱思唯尔爱尔兰科学有限公司。保留所有权利。
Background: Conformal radiotherapy requires reduced margins around the clinical target volume (CTV) with respect to traditional radiotherapy techniques. Therefore, high set-up accuracy and reproducibility are mandatory.Purpose: To investigate the effectiveness of two different immobilization techniques during conformal radiotherapy of prostate cancer with small fields.Materials and methods: 52 patients with prostate cancer were treated by conformal three- or four-held techniques with radical or adjuvant intent between November 1996 and March 1998. In total, 539 portal images were collected on a weekly basis for at least the first 4 weeks of the treatment on lateral and anterior Is MV X-ray fields. The average number of sessions monitored per patient was 5.7 (range 4-10). All patients were immobilized with an alpha-cradle system; 25 of them were immobilized at the pelvis level (group A) and the remaining 27 patients were immobilized in the legs (group B). The shifts with respect to the simulation condition were assessed by measuring the distances between the same bony landmarks and the held edges. The global distributions of cranio-caudal (CC), posterior-anterior (PA) and left-right (LR) shifts were considered; for each patient random and systematic error components were assessed by following the procedure suggested by Bijhold et al. (Bijhold J, Lebesque JV, Hart AAM, Vijlbrief RE. Maximising set-up accuracy using portal images as applied to a conformal boost technique for prostatic cancer. Radiother. Oncol. 1992;24:261-271). For each patient the average isocentre (3D) shift was assessed as the quadratic sum of the average shifts in the three directions.Results: Group B showed a better accuracy and reproducibility than group A for PA shifts (2.6 versus 4.4 mm, 1 SD), LR shifts (2.4 versus 3.6 mm, 1 SD) and CC shifts (2.7 versus 3.3 mm, 1 SD). Furthermore, group B showed a rate of large PA shifts (>5 mm) equal to 4.4% with respect to the 21.6% of group A (P < 0.0001). This value was also better than the corresponding value found in a previously investigated group of 21 non-immobilized patients (Italia C, Fiorino C, Ciocca M, et al. Quality control by portal film analysis of the conformal radiotherapy of prostate cancer: comparison between two different institutions and treatment techniques (abstract). Radiother. Oncol. 1997;43(Suppl. 2):S16, 16.8%, P = 0.001). For both groups there was no clear prevalence of one component (systematic or random) with respect to the other. The average isocentre shifts (averaged on all patients) were 3.0 mm (+/-1.4 mm, I SD) for group B and 5.0 mm (+/-2.8 mm, 1 SD) for group A against a value of 4.4 mm (+/-2.4 mm, I SD) for the previously investigated non-immobilized patient group.Conclusions: Immobilization of the legs with an alpha-cradle system seems to improve both the accuracy and reproducibility of the positioning of patients treated for prostate cancer with respect to alpha-cradle pelvic-abdomen immobilization. Based on these data, we decided to use the legs immobilization system and to reduce the margin around the CTV (from 10 to 8 mm) in the PA direction. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.