Pilot Study of Regional Lung Ventilation

Investigators hypothesize that a high resolution regional ventilation image (HRVI) based on 4D-CT imaging will correlate with the current low resolution state-of-the-art (SPECT-CT), which is the conventional way of measuring ventilation. HRVI may be a tool that could be widely used throughout the radiation therapy community because most radiation oncologists routinely employ 4D-CT technology in their own clinics. Investigators plan to test this hypothesis by comparing ventilation patterns on SPECT-CT images to HRVIs using a DICE analysis. As SPECT ventilation imaging is not included in our standard care, this study thus is designed as a pilot study. Based on published data, the difference between the two methods for calculating the regional ventilation in the lower 50% ventilation volume is expected to have a standard deviation of about 0.1. Therefore, the 95% confidence interval for the difference in the regional ventilation between SPECT-CT and 4D-CT pre-treatment would have a width of no more than 0.14 if 10 patients are enrolled and as small as 0.10 when 20 patients are registered.