Spect-guidance to Reduce Radioactive Dose to FunctioningLung for Stage III Non-small Cell Lung Cancer

Abstract

<br/><b>Objective</b>: To investigate the treatment effect of additional information obtained by single photon emissioncomputed tomography (SPECT) lung perfusion imaging (LPI) in the radiotherapy planning process for patientswith stage III non–small cell lung cancer (NSCLC). <br/><b>Methods</b>: 39 patients with stage III NSCLC were enrolled.Gross tumor volume (GTV) was outlined by SPECT/CT images, SPECT-LPIs being used to define functionallung (FL) and non-functional lung (NFL) regions. Two sets of IMRT plans were designed to deliver 64Gy toPTV. One was a regular IMRT plan using CT images only (Plan 1), and the other was a corresponding IMRTplan using co-registered images (Plan 2). FLVx (the % volume of functional lung receiving ≥x Gy) and WLVx(% volume of whole lung to receive ≥x Gy) were compared by paired Student’s t test. Kendalls correlation wasused to analyze the factor (s) related with the FLV20 decrease. <br/><b>Results</b>: Compared with plan 1, both WLVx andFLVx were decreased in plan 2. WLV10, WLV15, WLV20, WLV25, WLV30 and WLV35 decreased 9.7%, 13.8%, 17.2%,12.9%, 9.8% and 9.8%, and FLV10, FLV15, FLV20, FLV25, FLV30 and FLV35 decreased 10.8%, 14.6%, 17.3%, 14.5%,14.5% and 10.5%. FLVx decreased significantly compared with WLVx. There were significant differences in WLV10,WLV15, WLV20, WLV25, WLV3 and FLV10, FLV15, FLV20, FLV25, FLV30 between plan 1 and plan 2 (P=0.002, 0.000, 0.000,0.005, 0.027 and 0.002, 0.000, 0.000, 0.006, 0.010). According to Kendall correlation analysis, NFL had a negativerelation with the percentage FLV20 decrease (r=-0.559, P<0.01), while the distance of PTV and NFL center hada significantly positive relation with the percentage of FLV20 decrease (r=0.768, P<0.01). <br/><b>Conclusion</b>: Routineuse of SPECT-LPI for patients undergoing radiotherapy planning for stage III NSCLC appears warranted.