Objective: To investigate the treatment effect of additional information obtained by single photon emission computed tomography (SPECT) lung perfusion imaging (LPI) in the radiotherapy planning process for patients with stage III non-small cell lung cancer (NSCLC).
Methods: 39 patients with stage III NSCLC were enrolled. Gross tumor volume (GTV) was outlined by SPECT/CT images, SPECT-LPIs being used to define functional lung (FL) and non-functional lung (NFL) regions. Two sets of IMRT plans were designed to deliver 64Gy to PTV. One was a regular IMRT plan using CT images only (Plan 1), and the other was a corresponding IMRT plan 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 was used to analyze the factor (s) related with the FLV20 decrease.
Results: Compared with plan 1, both WLVx and FLVx 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 negative relation with the percentage FLV20 decrease (r=-0.559, P<0.01), while the distance of PTV and NFL center had a significantly positive relation with the percentage of FLV20 decrease (r=0.768, P<0.01).
Conclusion: Routine use of SPECT-LPI for patients undergoing radiotherapy planning for stage III NSCLC appears warranted.