Anatomy-wise lung ventilation imaging for precise functional lung avoidance radiation therapy

Abstract

Objective. This study aimed to propose a method for obtaining anatomy-wise lung ventilation image (VIaw) that enables functional assessment of lung parenchyma and tumor-blocked pulmonary segments. The VIaw was used to define multiple functional volumes of the lung and thereby support radiation treatment planning. Approach. A super-voxel-based method was employed for functional assessment of lung parenchyma to generate VIsvd. In the VIsvd of the 11 patients with tumor blockage of the airway, the functional value in tumor-blocked segments was set to 0 to generate the VIaw. The lung was divided into regions of high functional volume (HFV), unrecoverable low functional volume (LFV), and recoverable LFV (rLFV, the region in the tumor-blocked segment with a high function value based on the VIsvd) to design three intensity-modulated photon plans for five patients. These plans were an anatomical-lung-guided plan (aPlan), a functional-lung-guided plan (fPlan), and a recoverable functional-lung-guided plan (rfPlan) where the latter protected both HFV and rLFV. Main results. The LFV in the reference ventilation images and the tumor-blocked segments had a high overlap similarity coefficient value of 0.90 ± 0.07. The mean Spearman correlation between the VIaw and reference ventilation images was 0.72 ± 0.05 for the patient with tumor blockage of the airway. The V20 and mean dose of rLFV in rfPlan were lower than those in aPlan by 12.1 ± 8.4% and 13.0 ± 6.4%, respectively, and lower than those in fPlan by 14.9 ± 9.8% and 15.9 ± 6.5%, respectively. Significance. The VIaw can reach a moderate-strong correlation with reference ventilation images and thus can identify rLFV to support treatment planning to preserve lung function.