Intensity modulated radiotherapy of non-small-cell lung cancer incorporating SPECT ventilation imaging
Intensity modulated radiotherapy of non-small-cell lung cancer incorporating SPECT ventilation imaging
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DOI：
10.1118/1.3358128
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发表时间：
2010-04-01
期刊：
影响因子：
3.8
通讯作者：
Wong, Eugene
中科院分区：
文献类型：
--
作者：
Munawar, Iram;Yaremko, Brian P.;Wong, Eugene
研究方法：对于连续10例III期非小细胞肺癌患者，作者获得了通气/灌注SPECT扫描和四维CT扫描，用于治疗计划。每次通气扫描与相应的计划CT配准，并且对应于最大SPECT计数的>= 50%（vv 50）或>= 70%（vv 70）的通气量被自动分割。对于每例患者，生成三个IMRT计划：一个使用根据基于非功能性肺的平均肺剂量和肺v20优化的九个等距射束;第二个使用九个等距射束，以避免vv 50和vv 70;以及第三计划，其仅使用三个射束，其中基于在每10度机架角度处为每个适形射束计算的最小平均通气肺剂量来选择机架角度，vv 50和vv 70。结果剂量体积直方图指数计算每个计划，并进行了比较，以量化的潜在效用通气SPECT在此setting.Results：两个患者组的基础上（i）PTV和vv 50和（ii）的平均角平均通气肺剂量（AAMvLD）之间的重叠量。第一个参数量化PTV与通气良好的肺的接近度，第二个参数量化PTV周围的通气程度。对于第1组患者，< 5%的vv 50与PTV重叠。对于第2组患者，>5%的vv 50与PTV重叠。组1进一步分为亚组1A和1B：对于亚组1A，AAMvLD>18戈伊，意味着功能性肺包围PTV;对于亚组1B，AAMvLD < 18戈伊，意味着通气良好的肺不完全包围PTV。对于亚组1A，使用通气肺避免生成的计划将剂量降低到vv 50和vv 70，低于正常肺的耐受剂量，PTV的覆盖范围可接受。对于亚组1B，通过三射束计划的射束方向优化，降低了全肺和通气良好肺的剂量。对于第2组，没有显着的剂量优势，使用SPECT为基础的通气信息在IMRT计划optimization.Conclusions：总之，它是可行的，使用SPECT通气扫描优化IMRT束方向，随后，减少剂量通气肺时，重叠的PTV和通气肺是最小的，PTV不包围通气肺。通气SPECT扫描的潜在受益可通过重叠体积和AAMvLD的预先计划评估来确定。
Methods: For ten consecutive stage III non-small-cell lung cancer patients, the authors obtained both ventilation/perfusion SPECT scans and four-dimensional CT scans for treatment planning purposes. Each ventilation scan was registered with the corresponding planning CT and ventilation volumes corresponding to either >= 50% (vv50) or >= 70% (vv70) of the maximum SPECT count were automatically segmented. For each patient, three IMRT plans were generated: One using nine equally spaced beams optimized according to nonfunctional lung based mean lung dose and lung v20; a second using nine equally spaced beams optimized to avoid vv50 and vv70; and a third plan using only three beams with gantry angles chosen based on minimum mean ventilated lung dose calculated for each conformal beam at every 10 degrees gantry angle avoiding vv50 and vv70. Resultant dose volume histogram indices were calculated for each plan and were compared with respect to calculated SPECT-based ventilation parameters in order to quantify the potential utility of ventilation SPECT in this setting.Results: Two patient groups were identified based on (i) the overlap volume between PTV and vv50 and (ii) the average angular mean ventilated lung dose (AAMvLD). The first parameter quantifies the proximity of the PTV to well ventilated lung and the second parameter quantifies the degree of ventilation that surrounds the PTV. For group 1 patients, < 5% of the vv50 overlapped with the PTV. For group 2 patients, >5% of the vv50 overlapped the PTV. Group 1 was further classified into subgroups 1A and 1B: For subgroup 1A, AAMvLD is >18 Gy, implying that the functional lung surrounds the PTV; for subgroup 1B, AAMvLD is < 18 Gy, implying that the well ventilated lung does not completely surround PTV. For subgroup 1A, the plans generated using ventilated lung avoidance reduced dose to vv50 and vv70, with below tolerance dose to normal lung and acceptable coverage of the PTV. For subgroup 1B, the dose to the total lung and well ventilated lung are reduced with the beam direction optimization for the three-beam plan. For group 2, there was no significant dosimetric advantage of using SPECT-based ventilation information in IMRT plan optimization.Conclusions: In conclusion, it is feasible to use SPECT ventilation scans to optimize IMRT beam direction and, subsequently, to reduce dose to ventilated lung when overlap of the PTV and the ventilated lung is minimal and that the PTV is not surrounded by the ventilated lung. The potential benefit of ventilation SPECT scanning can be determined by preplanning assessment of overlap volumes and the AAMvLD.