Hoover Douglas A, Reid Robert H, Wong Eugene, Stitt Larry, Sabondjian Eric, Rodrigues George B, Jaswal Jasbir K, Yaremko Brian P
Department of Physics and Engineering, London Regional Cancer Program, University of Western Ontario, London, Ontario, Canada; Department of Oncology, University of Western Ontario, London, Ontario, Canada; Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
J Med Imaging Radiat Oncol. 2014 Apr;58(2):214-22. doi: 10.1111/1754-9485.12145. Epub 2013 Dec 25.
When we irradiate lung cancer, the radiation dose that can be delivered safely is limited by the risk of radiation pneumonitis (RP) in the surrounding normal lung. This risk is dose-dependent and is commonly predicted using metrics such as the V20, which are usually formulated assuming homogeneous pulmonary function. Because in vivo pulmonary function is not homogeneous, if highly functioning lung can be identified beforehand and preferentially avoided during treatment, it might be possible to reduce the risk of RP, suggesting the utility of function-based prediction metrics.
We retrospectively identified 26 patients who received ventilation and perfusion single photon emission computed tomography (SPECT-CT) immediately prior to curative-intent radiation therapy. Patients were separated into non-RP and RP groups. As-treated dose-volume histogram (DVH), perfusion-SPECT-based and ventilation-SPECT-based dose-function histogram (DFH) parameters were defined for each group and were tested for differences. The relative utilities of ventilation-based and perfusion-based DFH metrics were assessed using receiver operating characteristic (ROC) analysis.
The standard mean lung dose (MLD) was significantly higher in the RP group; the standard V20 and V30 were higher in the RP group but not significantly. Perfusion-weighted and ventilation-weighted values of the MLD, V20 and V30 were all significantly higher in the RP group. ROC analysis suggested that SPECT-based DFH parameters outperformed standard DVH parameters as predictors of RP.
SPECT-based DFH parameters appear to be useful as predictors of RP.
在对肺癌进行放射治疗时，可安全给予的辐射剂量受到周围正常肺组织发生放射性肺炎（RP）风险的限制。这种风险与剂量相关，通常使用诸如V20等指标进行预测，这些指标通常是在假设肺功能均匀的情况下制定的。由于体内肺功能并非均匀一致，如果能够事先识别出功能良好的肺组织并在治疗过程中优先避开，就有可能降低RP的风险，这表明基于功能的预测指标具有实用性。
我们回顾性地确定了26例在进行根治性放射治疗前立即接受通气和灌注单光子发射计算机断层扫描（SPECT-CT）的患者。将患者分为无RP组和RP组。为每组定义了治疗后的剂量体积直方图（DVH）、基于灌注SPECT和基于通气SPECT的剂量功能直方图（DFH）参数，并对其差异进行了测试。使用受试者操作特征（ROC）分析评估基于通气和基于灌注的DFH指标的相对实用性。
RP组的标准平均肺剂量（MLD）显著更高；RP组的标准V20和V30更高，但差异不显著。RP组中MLD、V20和V30的灌注加权值和通气加权值均显著更高。ROC分析表明，基于SPECT的DFH参数作为RP的预测指标优于标准DVH参数。
基于SPECT的DFH参数似乎可作为RP的预测指标。
