Texas Oncology; Shobhit University.
J Appl Clin Med Phys. 2016 Jul 16;17(6):69-77. doi: 10.1120/jacmp.v17i6.6029.
This study was designed to determine whether volumetric imaging could identify consistent alternative prescription methods to Manchester/point A when prescribing radiation dose in the treatment of cervical cancer using HDR intracavitary brachy-therapy (ICBT). One hundred and twenty-five treatment plans of 25 patients treated for carcinoma of the cervix were reviewed retrospectively. Each patient received 5 fractions of HDR ICBT following initial cisplatin-based pelvic chemoradiation, and radiation dose was originally prescribed to point A (ICRU-38). The gross tumor volume (GTV) and high-risk clinical target volume (HR-CTV) were contoured in three dimensions on the CT datasets, and inferior-superior, anterior-posterior, and left-right dimensions HR-CTV were recorded along with multiple anatomic and skeletal dimensions for each patient. The least square-best fit regression lines were plotted between one half of the HR-CTV width and pelvic cavity dimension at femoral head level and at maximum cavity dimension. The points in both plots lie reasonably close to straight lines and are well defined by straight lines with slopes of 0.15 and 0.17; intercept on y-axes of -0.08 and -0.03, point A, at the same level as defined based on applicator coordinates, is defined using this correlation, which is a function of distance between femoral heads/dimensions of maximum pelvic cavity width. Both relations, defined by straight lines, provide an estimated location of point A, which provides adequate coverage to the HR-CTV compared to the point A defined based on applicator coordinates. The point A defined based on femoral head distance would, therefore, be a reasonable surrogate to use for dose prescription because of subjective variation of cavity width dimension. Simple surrogate anatomic/skeletal landmarks can be useful for prescribing radiation dose when treating cervical cancer using intracavitary brachytherapy in limited-resource settings. Our ongoing work will continue to refine these models.
本研究旨在确定容积成像是否可以在使用 HDR 腔内近距离治疗（ICBT）治疗宫颈癌时为曼彻斯特/点 A 规定放射剂量时，确定是否存在一致的替代处方方法。回顾性分析了 25 例宫颈癌患者的 125 例治疗计划。每位患者在初始顺铂为基础的盆腔放化疗后接受 5 次 HDR ICBT 治疗，最初将放射剂量规定为点 A（ICRU-38）。在 CT 数据集上对大体肿瘤体积（GTV）和高危临床靶区（HR-CTV）进行三维勾画，并记录 HR-CTV 的下上、前后和左右尺寸，以及每位患者的多个解剖和骨骼尺寸。在股骨头水平和最大腔尺寸处，绘制 HR-CTV 宽度的一半与骨盆腔尺寸之间的最小二乘最佳拟合回归线。两个图中的点都相当接近直线，并且用斜率为 0.15 和 0.17 的直线很好地定义；y 轴上的截距为-0.08 和-0.03，点 A 与基于施源器坐标定义的点 A 位于同一水平，该点 A 由股骨之间的距离/最大骨盆宽度的尺寸定义。这两条直线定义的关系为点 A 提供了一个估计位置，与基于施源器坐标定义的点 A 相比，它可以为 HR-CTV 提供足够的覆盖范围。因此，由于腔宽尺寸的主观变化，基于股骨头距离定义的点 A 将成为剂量处方的合理替代物。在资源有限的情况下，使用腔内近距离治疗治疗宫颈癌时，简单的替代解剖/骨骼标志可用于规定放射剂量。我们正在进行的工作将继续改进这些模型。
