Department of Radiation Oncology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, South Korea.
Int J Radiat Oncol Biol Phys. 2012 Sep 1;84(1):e29-34. doi: 10.1016/j.ijrobp.2012.02.055. Epub 2012 Apr 13.
To evaluate the feasibility of 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT)-guided conformal brachytherapy treatment planning in patients with cervical cancer.
Pretreatment FDG-PET/CT was performed for 12 patients with cervical cancer. Brachytherapy simulation was performed after an external-beam radiation therapy median dose of 4140 cGy. Patients underwent FDG-PET/CT scans with placement of tandem and ovoid applicators. The gross tumor volume (GTV) was determined by adjusting the window and level to a reasonable value and outlining the edge of the enhancing area, which was done in consultation with a nuclear medicine physician. A standardized uptake value profile of the tumor margin was taken for each patient relative to the maximum uptake value of each tumor and analyzed. The plan was designed to deliver 400 cGy to point A (point A plan) or to cover the clinical target volume (CTV) (PET/CT plan).
The median dose that encompassed 95% of the target volume (D95) of the CTV was 323.0 cGy for the point A plan vs 399.0 cGy for the PET/CT plan (P=.001). The maximum standardized uptake values (SUV(max)) of the tumors were reduced by a median of 57% (range, 13%-80%). All but 1 patient presented with discernable residual uptake within the tumors. The median value of the thresholds of the tumors contoured by simple visual analysis was 41% (range, 23%-71%).
In this study, the PET/CT plan was better than the conventional point A plan in terms of target coverage without increasing the dose to the normal tissue, making optimized 3-dimensional brachytherapy treatment planning possible. In comparison with the previously reported study with PET or CT alone, we found that visual target localization was facilitated by PET fusion on indeterminate CT masses. Further studies are needed to characterize the metabolic activity detected during radiation therapy for more reliable targeting.
评估 18F-氟代脱氧葡萄糖（FDG）正电子发射断层扫描（PET）/计算机断层扫描（CT）引导的适形近距离治疗计划在宫颈癌患者中的可行性。
对 12 例宫颈癌患者进行了治疗前 FDG-PET/CT 检查。在 4140 cGy 中值外照射放疗后进行近距离治疗模拟。患者接受 FDG-PET/CT 扫描，同时放置子宫托和卵圆型施源器。通过调整窗口和水平以获得合理的值并勾勒增强区域的边缘来确定大体肿瘤体积（GTV），这是与核医学医师协商完成的。对每位患者的肿瘤边缘进行肿瘤摄取标准化值轮廓测量，并进行分析。计划设计为将 400 cGy 输送至 A 点（A 点计划）或覆盖临床靶体积（CTV）（PET/CT 计划）。
CTV 的 95%靶体积涵盖的中位剂量（D95），A 点计划为 323.0 cGy，PET/CT 计划为 399.0 cGy（P=.001）。肿瘤的最大标准化摄取值（SUV(max)）中位数降低了 57%（范围为 13%-80%）。除 1 例患者外，所有患者的肿瘤内均存在可识别的残留摄取。通过简单的视觉分析勾勒出的肿瘤阈值的中位数为 41%（范围为 23%-71%）。
在这项研究中，与传统的 A 点计划相比，PET/CT 计划在不增加正常组织剂量的情况下更好地覆盖了靶区，使优化的 3 维近距离治疗计划成为可能。与之前单独使用 PET 或 CT 的报道研究相比，我们发现 PET 融合在不确定的 CT 肿块上有助于目标的定位。需要进一步的研究来描述放疗过程中检测到的代谢活性，以实现更可靠的靶向。
