Value of lung perfusion in stage III non-small cell lung cancer patients treated with three dimensional conformal radiotherapy

Objective: To investigate the value of lung perfusion single photon emission computed tomography (SPECT) scans in patients with stage III non-small cell lung cancer (NSCLC) treated with three dimensional conformal radiotherapy (3DCRT). Methods: Eight patients with stage III NSCLC who were candidated for 3DCRT were enrolled. All the patients had PET-CT scans and SPECT scans. The imagings were accurately co-registered in the planning system. The PET-CT images were used to define the gross tumor volume, and the SPECT images were used to define a volume of perfused "functioning" lung (FL). The planning objective was to minimize the dose to FL. Statistical analysis was made for the difference between the two sets of 3DCRT plans. Results: After 3DCRT was optimized, both the percentage of whole lung volume received dose ≥xGy (WLVx) and the percentage of functional lung volume received dose ≥xGy (FLVx) were decreased. However, the FLVx was decreased significantly. There were significant differences in WLV10, WLV15, WLV20, WLV25, WLV30 and FLV10, FLV15, FLV20, FLV25, FLV30 between before and after the 3DCRT was optimized (P=0.001, 0.002, 0.014, 0.046, 0.017 and 0.000, 0.000, 0.004, 0.027, 0.023). Conclusion: SPECT lung perfusion images are helpful in optimizing radiotherapy plans for patients with stage III NSCLC, especially for patients with large perfusion deficits.