Department of Radiotherapy, Comprehensive Cancer Centre Vienna, Medical University of Vienna , Vienna , Austria.
Acta Oncol. 2013 Oct;52(7):1345-52. doi: 10.3109/0284186X.2013.813068. Epub 2013 Aug 2.
The aim of the study was to improve computed tomography (CT)-based high-risk clinical target volume (HR CTV) delineation protocols for cervix cancer patients, in settings without any access to magnetic resonance imaging (MRI) at the time of brachytherapy. Therefore the value of a systematic integration of comprehensive three-dimensional (3D) documentation of repetitive gynecological examination for CT-based HR CTV delineation protocols, in addition to information from FIGO staging, was investigated. In addition to a comparison between reference MRI contours and two different CT-based contouring methods (using complementary information from FIGO staging with or without additional 3D clinical drawings), the use of standardized uterine heights was also investigated.
Thirty-five cervix cancer patients with CT- and MR-images and 3D clinical drawings at time of diagnosis and brachytherapy were included. HR CTV(stage) was based on CT information and FIGO stage. HR CTV(stage + 3Dclin) was contoured on CT using FIGO stage and 3D clinical drawing. Standardized HR CTV heights were: 1/1, 2/3 and 1/2 of uterine height. MRI-based HR CTV was delineated independently. Resulting widths, thicknesses, heights, and volumes of HR CTV(stage), HR CTV(stage + 3Dclin) and MRI-based HR CTV contours were compared.
The overall normalized volume ratios (mean ± SD of CT/MRI(ref) volume) of HR CTV(stage) and HR stage + 3Dclin were 2.6 (± 0.6) and 2.1 (± 0.4) for 1/1 and 2.3 (± 0.5) and 1.8 (± 0.4), for 2/3, and 1.9 (± 0.5) and 1.5 (± 0.3), for 1/2 of uterine height. The mean normalized widths were 1.5 ± 0.2 and 1.2 ± 0.2 for HR CTV(stage) and HR CTV(stage + 3Dclin), respectively (p < 0.05). The mean normalized heights for HR CTV(stage) and HR CTV(stage + 3Dclin) were both 1.7 ± 0.4 for 1/1 (p < 0.05.), 1.3 ± 0.3 for 2/3 (p < 0.05) and 1.1 ± 0.3 for 1/2 of uterine height.
CT-based HR CTV contouring based on FIGO stage alone leads to large overestimation of width and volume. Target delineation accuracy can systematically improve through incorporation of additional information from comprehensive 3D documentation of repetitive gynecological examination in the contouring protocol, and thus help to improve the accuracy of dose optimization in settings with limited access to imaging facilities at the time of brachytherapy. If CT information is only available, minimum 2/3 of uterine height may be a good surrogate for the height of HR CTV.
本研究旨在改进宫颈癌患者基于计算机断层扫描（CT）的高危临床靶区（CTV）勾画方案，因为在近距离放疗时无法获得任何磁共振成像（MRI）。因此，研究了在没有 MRI 的情况下，系统地整合重复妇科检查的全面三维（3D）记录对基于 CT 的高危 CTV 勾画方案的价值，除了 FIGO 分期提供的信息外。除了比较参考 MRI 轮廓和两种不同的 CT 勾画方法（使用 FIGO 分期的互补信息，或结合额外的 3D 临床绘图）外，还研究了标准化子宫高度的使用。
共纳入 35 例宫颈癌患者，在诊断和近距离放疗时均有 CT 和 MRI 图像和 3D 临床绘图。高危 CTV（分期）基于 CT 信息和 FIGO 分期。高危 CTV（分期+3Dclin）使用 FIGO 分期和 3D 临床绘图在 CT 上勾画。标准化的高危 CTV 高度为：子宫高度的 1/1、2/3 和 1/2。独立勾画基于 MRI 的高危 CTV。比较高危 CTV（分期）、高危 CTV（分期+3Dclin）和基于 MRI 的高危 CTV 轮廓的宽度、厚度、高度和体积。
高危 CTV（分期）和高危 CTV（分期+3Dclin）的总体归一化体积比（CT/MRI(ref)体积平均值±标准差）分别为 1/1 时的 2.6（±0.6）和 2.1（±0.4），2/3 时的 2.3（±0.5）和 1.8（±0.4），1/2 时的 1.9（±0.5）和 1.5（±0.3）。高危 CTV（分期）和高危 CTV（分期+3Dclin）的平均归一化宽度分别为 1.5±0.2 和 1.2±0.2（p<0.05）。高危 CTV（分期）和高危 CTV（分期+3Dclin）的平均归一化高度均为 1/1 时的 1.7±0.4（p<0.05），2/3 时的 1.3±0.3（p<0.05），1/2 时的 1.1±0.3。
基于 FIGO 分期的 CT 高危 CTV 勾画会导致宽度和体积的过度估计。通过在勾画方案中纳入重复妇科检查的全面 3D 记录的额外信息，可以系统地提高靶区勾画的准确性，从而有助于在近距离放疗时限制影像学设施的情况下提高剂量优化的准确性。如果只有 CT 信息，则子宫高度的 2/3 可能是高危 CTV 高度的良好替代物。
