基于 CT 和 MRI 的局部晚期宫颈癌近距离放疗临床靶区勾画的比较和共识指南。
Comparison and consensus guidelines for delineation of clinical target volume for CT- and MR-based brachytherapy in locally advanced cervical cancer.
机构信息
Brigham & Women's Hospital/Dana-Farber Cancer Institute, Boston, Massachusetts.
Medical College of Wisconsin, Milwaukee, Wisconsin.
出版信息
Int J Radiat Oncol Biol Phys. 2014 Oct 1;90(2):320-8. doi: 10.1016/j.ijrobp.2014.06.005.
OBJECTIVE
To create and compare consensus clinical target volume (CTV) contours for computed tomography (CT) and 3-Tesla (3-T) magnetic resonance (MR) image-based cervical-cancer brachytherapy.
METHODS AND MATERIALS
Twenty-three experts in gynecologic radiation oncology contoured the same 3 cervical cancer brachytherapy cases: 1 stage IIB near-complete response (CR) case with a tandem and ovoid, 1 stage IIB partial response (PR) case with tandem and ovoid with needles, and 1 stage IB2 CR case with a tandem and ring applicator. The CT contours were completed before the MRI contours. These were analyzed for consistency and clarity of target delineation using an expectation maximization algorithm for simultaneous truth and performance level estimation (STAPLE), with κ statistics as a measure of agreement between participants. The conformity index was calculated for each of the 6 data sets. Dice coefficients were generated to compare the CT and MR contours of the same case.
RESULTS
For all 3 cases, the mean tumor volume was smaller on MR than on CT (P<.001). The κ and conformity index estimates were slightly higher for CT, indicating a higher level of agreement on CT. The Dice coefficients were 89% for the stage IB2 case with a CR, 74% for the stage IIB case with a PR, and 57% for the stage IIB case with a CR.
CONCLUSION
In a comparison of MR-contoured with CT-contoured CTV volumes, the higher level of agreement on CT may be due to the more distinct contrast medium visible on the images at the time of brachytherapy. MR at the time of brachytherapy may be of greatest benefit in patients with large tumors with parametrial extension that have a partial or complete response to external beam. On the basis of these results, a 95% consensus volume was generated for CT and for MR. Online contouring atlases are available for instruction at http://www.nrgoncology.org/Resources/ContouringAtlases/GYNCervicalBrachytherapy.aspx.
目的
为基于计算机断层扫描（CT）和 3 特斯拉（3-T）磁共振（MR）图像的宫颈癌近距离放射治疗创建并比较共识临床靶区（CTV）轮廓。
方法和材料
23 名妇科放射肿瘤学专家对 3 例宫颈癌近距离放射治疗病例进行了轮廓勾画：1 例 2B 期接近完全缓解（CR）病例，使用纵膈和子宫环型施源器；1 例 2B 期部分缓解（PR）病例，使用纵膈和子宫环型施源器加针；1 例 1B2 期 CR 病例，使用纵膈和子宫环型施源器。CT 轮廓在 MRI 轮廓之前完成。使用期望最大化算法同时进行真实和性能水平估计（STAPLE）分析这些轮廓，一致性和目标勾画的清晰度用κ统计量作为参与者之间的一致性度量。计算了每个 6 数据集的适形指数。生成 Dice 系数以比较同一病例的 CT 和 MR 轮廓。
结果
对于所有 3 例病例，MR 上肿瘤体积均小于 CT（P<.001）。CT 的κ和适形指数估计值略高，表明 CT 上的一致性水平更高。CR 期 1B2 病例的 Dice 系数为 89%，PR 期 2B 病例为 74%，CR 期 2B 病例为 57%。
结论
在比较 MR 勾画与 CT 勾画的 CTV 体积时，CT 上的一致性水平较高，可能是由于在近距离放射治疗时图像上的对比剂更明显。在近距离放射治疗时，MR 对有部分或完全缓解的大肿瘤和宫旁延伸的患者可能最有益。基于这些结果，生成了 CT 和 MR 的 95%共识体积。在线轮廓图谱可在 http://www.nrgoncology.org/Resources/ContouringAtlases/GYNCervicalBrachytherapy.aspx 获得。
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