McGibney C, Holmberg O, McClean B, Williams C, McCrea P, Sutton P, Armstrong J
Department of Radiation Oncology, St. Luke's Hospital, Dublin, Ireland.
Int J Radiat Oncol Biol Phys. 1999 Sep 1;45(2):339-50. doi: 10.1016/s0360-3016(99)00095-4.
To evaluate, preclinically, the potential for dose escalation of continuous, hyperfractionated, accelerated radiation therapy (CHART) for non small-cell lung cancer (NSCLC), we examined the strategy of omission of elective nodal irradiation with and without the application of three-dimensional conformal radiation technology (3DCRT).
2D, conventional therapy plans were designed according to the specifications of CHART for 18 patients with NSCLC (Stages Ib, IIb, IIIa, and IIIb). Further plans were generated with the omission of elective nodal irradiation (ENI) from the treatment portals (2D minus ENI plans [2D-ENI plans]). Both sets were inserted in the patient's planning computed tomographies (CTs). These reconstructed plans were then compared to alternative, three-dimensional treatment plans which had been generated de novo, with the omission of ENI: 3D minus elective nodal irradiation (3D-ENI plans). Dose delivery to the planning target volumes (PTVs) and to the organs at risk were compared between the 3 sets of corresponding plans. The potential for dose escalation of each patient's 2D-ENI and 3D-ENI plan beyond 54 Gy, standard to CHART, was also determined.
PTV coverage was suboptimal in the 2D CHART and the 2D-ENI plans. Only in the 3D-ENI plans did 100% of the PTV get > or = 95% of the dose prescribed (i.e., 51.5 Gy [51.3-52.2]). Using 3D-ENI plans significantly reduced the dose received by the spinal cord, the mean and median doses to the esophagus and the heart. It did not significantly reduce the lung dose when compared to 2D-ENI plans. Escalation of the dose (minimum > or = 1 Gy) with optimal PTV coverage was possible in 55.5% of patients using 3D-ENI, but was possible only in 16.6% when using the 2D-ENI planning strategy.
3DCRT is fundamental to achieving optimal PTV coverage in NSCLC. A policy of omission of elective nodal irradiation alone (and using 2D technology) will not achieve optimal PTV coverage or dose escalation. 3DCRT with omission of ENI can achieve true escalation of CHART in 55.5% of tumors, depending on their site and N-stage.
为了在临床前评估非小细胞肺癌（NSCLC）连续、超分割、加速放射治疗（CHART）剂量递增的潜力，我们研究了在应用和不应用三维适形放射技术（3DCRT）的情况下省略选择性淋巴结照射的策略。
根据CHART的规范为18例NSCLC患者（Ib期、IIb期、IIIa期和IIIb期）设计二维常规治疗计划。进一步生成从治疗野中省略选择性淋巴结照射（ENI）的计划（二维减去ENI计划[2D-ENI计划]）。将这两组计划都插入患者的计划计算机断层扫描（CT）中。然后将这些重建计划与从头生成的、省略了ENI的三维治疗计划进行比较：三维减去选择性淋巴结照射（3D-ENI计划）。比较三组相应计划中计划靶体积（PTV）和危及器官的剂量输送情况。还确定了每位患者的2D-ENI和3D-ENI计划超出CHART标准的54 Gy进行剂量递增的潜力。
二维CHART和二维ENI计划中PTV覆盖情况欠佳。只有在三维ENI计划中，100%的PTV能获得规定剂量（即51.5 Gy[51.3 - 52.2]）的≥95%。使用三维ENI计划显著降低了脊髓、食管和心脏所接受的平均和中位剂量。与二维ENI计划相比，它没有显著降低肺剂量。使用三维ENI计划时，55.5%的患者有可能在PTV覆盖最佳的情况下进行剂量递增（最小≥1 Gy），而使用二维ENI计划策略时只有16.6%的患者有可能。
3DCRT是在NSCLC中实现最佳PTV覆盖的基础。仅省略选择性淋巴结照射（并使用二维技术）的策略无法实现最佳PTV覆盖或剂量递增。根据肿瘤的部位和N分期，省略ENI的3DCRT可使55.5%的肿瘤实现CHART的真正剂量递增。
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