Room: AAPM ePoster Library
Radiation pneumonitis (RP) from radiation treatment for lung cancer patients is one of the toxicities physicians would like to avoid. Typical V20Gy=30-35% and mean lung dose =20-23Gy are the criteria to avoid radiation toxicities; however, some RPs still were observed after radiation treatment. This study is to use the ventilation maps calculated from 4DCT images to predict radiation pneumonitis (RP) for lung cancer patients.
Patients with lung disease treated with IMRT (total 50~70Gy) at a single institution between 2011 and 2019 were retrospectively identified from a prospectively collected database. Patients with a pretreatment and post-treatment 10-phase 4DCT scans and with Siemens E-Xamine (Siemens Medical Solutions, Concord, CA, USA) software compatibility were included. We imported secondary data from these 4D scans to create a CT ventilation and aeration using the E-Xamine. The Aeration map factored in the density of the lung tissue along with the ventilation. Pre-treatment CT with isodose levels, ventilation levels and tumor delineations (GTV, ITV and PTV) and delivered doses (20Gy and 5Gy) were registered to post-treatment CT to identify the possibility location of RP. Ventilation values within the tumor volume and isodose lines are analyzed and compared.
Among 6 patients, the repeat 4D lung and multiple diagnostic scans were done at approximately 1 year (range 3-24 months). Three patients have been identified by different radiologists as possible RP or radiation induced bronchiectasis at post-diagnostic scans, while three patients received similar treatment regimens did not develop RP. We found the maximum and mean ventilation values within 20Gy isodose line and RP development have positive correlation with p-value=0.09 for maximum ventilation.
Our Results indicates that the ventilation maps calculated from 4DCT images could be possibly used to predict radiation pneumonitis (RP) for lung cancer patients at 20Gy level.