Siva Shankar, Devereux Thomas, Ball David L, MacManus Michael P, Hardcastle Nicholas, Kron Tomas, Bressel Mathias, Foroudi Farshad, Plumridge Nikki, Steinfort Daniel, Shaw Mark, Callahan Jason, Hicks Rodney J, Hofman Michael S
Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia.
Technol Cancer Res Treat. 2016 Feb;15(1):114-21. doi: 10.1177/1533034614565534. Epub 2015 Jan 9.
Ga-68-macroaggregated albumin ((68)Ga-perfusion) positron emission tomography/computed tomography (PET/CT) is a novel imaging technique for the assessment of functional lung volumes. The purpose of this study was to use this imaging technique for functional adaptation of definitive radiotherapy plans in patients with non-small cell lung cancer (NSCLC).
This was a prospective clinical trial of patients with NSCLC who received definitive 3-dimensional (3D) conformal radiotherapy to 60 Gy in 30 fx and underwent pretreatment respiratory-gated (4-dimensional [4D]) perfusion PET/CT. The "perfused" lung volume was defined as all lung parenchyma taking up radiotracer, and the "well-perfused" lung volume was contoured using a visually adapted threshold of 30% maximum standardized uptake value (SUV max). Alternate 3D conformal plans were subsequently created and optimized to avoid perfused and well-perfused lung volumes. Functional dose volumetrics were compared using mean lung dose (MLD), V5 (volume receiving 5 Gy or more), V10, V20, V30, V40, V50, and V60 parameters.
Fourteen consecutive patients had alternate radiotherapy plans created based on functional lung volumes. When considering the original treatment plan, the dose to perfused and well-perfused functional lung volumes was similar to that of the conventional anatomical lung volumes with an average MLD of 12.15, 12.67, and 12.11 Gy, respectively. Plans optimized for well-perfused lung improved functional V30, V40, V50, and V60 metrics (all P values <.05). The functional MLD of well-perfused lung was improved by a median of 0.86 Gy, P < .01. However, plans optimized for perfused lung only showed significant improvement in the functional V60 dose parameter (median 1.00%, P = .04) but at a detriment of a worse functional V5 (median 3.33%, P = .05).
This study demonstrates proof of principle that 4D-perfusion PET/CT may enable functional lung avoidance during treatment planning of patients with NSCLC. Radiotherapy plans adapted to well-perfused but not perfused functional lung volumes allow for reduction in dose to functional lung using 3D conformal radiotherapy.
镓-68-大聚合白蛋白（（68）Ga灌注）正电子发射断层扫描/计算机断层扫描（PET/CT）是一种用于评估功能性肺容积的新型成像技术。本研究的目的是将这种成像技术用于非小细胞肺癌（NSCLC）患者确定性放疗计划的功能适应性调整。
这是一项针对NSCLC患者的前瞻性临床试验，这些患者接受了60 Gy分30次的确定性三维（3D）适形放疗，并在治疗前进行了呼吸门控（四维[4D]）灌注PET/CT检查。“灌注”肺容积定义为摄取放射性示踪剂的所有肺实质，“灌注良好”的肺容积通过视觉调整的最大标准化摄取值（SUV max）30%的阈值进行勾画。随后创建并优化替代的3D适形计划，以避免灌注和灌注良好的肺容积。使用平均肺剂量（MLD）、V5（接受5 Gy或更高剂量的体积）、V10、V20、V30、V40、V50和V60参数比较功能剂量体积学。
连续14例患者根据功能性肺容积制定了替代放疗计划。考虑原始治疗计划时，灌注和灌注良好的功能性肺容积所接受的剂量与传统解剖学肺容积相似，平均MLD分别为12.15、12.67和12.11 Gy。针对灌注良好的肺优化的计划改善了功能性V30、V40、V50和V60指标（所有P值<.05）。灌注良好的肺的功能性MLD中位数改善了0.86 Gy，P<.01。然而，仅针对灌注肺优化的计划仅在功能性V60剂量参数上有显著改善（中位数1.00%，P =.04），但代价是功能性V5更差（中位数3.33%，P =.05）。
本研究证明了原理，即4D灌注PET/CT可能在NSCLC患者的治疗计划期间实现功能性肺避让。适应于灌注良好但非灌注功能性肺容积的放疗计划允许使用3D适形放疗降低对功能性肺的剂量。
