Mah Katherine, Caldwell Curtis B, Ung Yee C, Danjoux Cyril E, Balogh Judith M, Ganguli S Nimu, Ehrlich Lisa E, Tirona Romeo
Department of Medical Physics, Toronto-Sunnybrook Regional Cancer Centre, Toronto, Ontario, Canada.
Int J Radiat Oncol Biol Phys. 2002 Feb 1;52(2):339-50. doi: 10.1016/s0360-3016(01)01824-7.
To prospectively study the impact of coregistering (18)F-fluoro-deoxy-2-glucose hybrid positron emission tomographic (FDG-PET) images with CT images on the planning target volume (PTV), target coverage, and critical organ dose in radiation therapy planning of non-small-cell lung carcinoma.
Thirty patients with poorly defined tumors on CT, referred for radical radiation therapy, underwent both FDG-PET and CT simulation procedures on the same day, in radiation treatment position. Image sets were coregistered using external fiducial markers. Three radiation oncologists independently defined the gross tumor volumes, using first CT data alone and then coregistered CT and FDG-PET data. Standard margins were applied to each gross tumor volume to generate a PTV, and standardized treatment plans were designed and calculated for each PTV. Dose-volume histograms were used to evaluate the relative effect of FDG information on target coverage and on normal tissue dose.
In 7 of 30 (23%) cases, FDG-PET information changed management strategy from radical to palliative. In 5 of the remaining 23 (22%) cases, new FDG-avid nodes were found within 5 cm of the primary tumor and were included in the PTV. The PTV defined using coregistered CT and FDG-PET would have been poorly covered by the CT-based treatment plan in 17--29% of cases, depending on the physician, implying a geographic miss had only CT information been available. The effect of FDG-PET on target definition varied with the physician, leading to a reduction in PTV in 24-70% of cases and an increase in 30-76% of cases. The relative change in PTV ranged from 0.40 to 1.86. On average, FDG-PET information led to a reduction in spinal cord dose but not in total lung dose, although large differences in dose to the lung were seen for a few individuals.
The coregistration of planning CT and FDG-PET images made significant alterations to patient management and to the PTV. Ultimately, changes to the PTV resulted in changes to the radiation treatment plans for the majority of cases. Where possible, we would recommend that FDG-PET data be integrated into treatment planning of non-small-cell lung carcinoma, particularly for three-dimensional conformal techniques.
前瞻性研究将（18）F-氟脱氧-2-葡萄糖混合正电子发射断层扫描（FDG-PET）图像与CT图像进行配准对非小细胞肺癌放射治疗计划中计划靶体积（PTV）、靶区覆盖范围及关键器官剂量的影响。
30例CT上肿瘤边界不清、拟行根治性放射治疗的患者于同一天在放射治疗体位下接受了FDG-PET和CT模拟检查。使用外部基准标记对图像集进行配准。三位放射肿瘤学家分别先仅使用CT数据，然后使用配准后的CT和FDG-PET数据独立确定大体肿瘤体积。对每个大体肿瘤体积应用标准边界以生成PTV，并为每个PTV设计和计算标准化治疗计划。使用剂量体积直方图评估FDG信息对靶区覆盖范围和正常组织剂量的相对影响。
30例患者中有7例（23%），FDG-PET信息使治疗策略从根治性变为姑息性。在其余23例中的5例（22%），在原发肿瘤5 cm范围内发现了新的FDG摄取阳性淋巴结并纳入PTV。根据医生不同，使用配准后的CT和FDG-PET定义的PTV在17% - 29%的病例中，基于CT的治疗计划覆盖不佳，这意味着若仅使用CT信息会出现靶区遗漏情况。FDG-PET对靶区定义的影响因医生而异，导致24% - 70% 的病例PTV减小，30% - 76% 的病例PTV增大。PTV的相对变化范围为0.40至1.86。平均而言，FDG-PET信息使脊髓剂量降低，但未使全肺剂量降低，尽管少数个体的肺剂量存在较大差异。
计划CT与FDG-PET图像的配准对患者管理和PTV产生了显著改变。最终，大多数病例中PTV的变化导致了放射治疗计划的改变。在可能的情况下，我们建议将FDG-PET数据纳入非小细胞肺癌的治疗计划，特别是对于三维适形技术。
