Comparison Of Functional And Anatomic Dosimetric Metrics During Radiotherapy For Predicting Radiation-induced Lung Toxicity In Patients With Locally Advanced Non-small Cell Lung Cancer

PurposeThe purpose of this study is to investigate perfusion(Q)single-photon emission computerized tomography(SPECT)-weighted dose-function histogram(DFH)during the mid-course of radiotherapy(RT)for predicting radiation-induced lung toxicity(RILT)in patients with non-small cell lung cancer(NSCLC).Material and methodsForty-two locally advanced NSCLC patients receiving chemoradiotherapy were enrolled prospectively.The simulation computerized tomography(CT),Q-SPECT were performed prior to and during RT(at approximately 40-45Gy).Baseline-DVH and during-DVH based on simulation CT,and baseline-DFH and during-DFH based on Q-SPECT were calculated respectively.The RILT grade was defined according to the Common Terminology Criteria for Adverse Events version 4.0.The development of RILT was considered as a binary variable: “Grade ? 1 group” and “Grade ? 2 group”.DFH was defined consistently using 30% above of normal maximal lung function.ResultsOf the 42 patients,the accumulative incidence of ? 2 grade RILT was 31%,incidence of ? 1 grade RILT was 69%.There were significant differences of functional dosimetric metrics FV5 – FV20 at increments of 5 Gy and functional MLD(FMLD)between the two groups patients(p < 0.05),similar results were also found in anatomical parameters from V5 to V20 and MLD(p < 0.05).The area under the receiver operating characteristic(ROC)curves(AUCs)for baseline-DVH parameters were 0.782-0.844,for during-DVH parameters were 0.798-0.865,for baseline-DFH parameters were 0.806-0.897,for during-DFH parameters were 0.812-0.918.Further principal components analysis showed that the AUCs were 0.849(p< 0.001)/ 0.851(p= 0.001),and 0.830(p< 0.001)versus 0.878(p< 0.001),for baseline / during-DVH and baseline / during-DFH,respectively.ConclusionsThough did not reach a statistic difference,during-DFH parameters based on the Q-SPECT may have more potential advangtages than anatomic parameters in predicting RILT in patients with locally advanced NSCLC.Further study with a larger sample size is needed to further validate.