Volume-based algorithm of lung dose optimization in novel dynamic arc radiotherapy for esophageal cancer

Abstract

This study aims to develop a volume-based algorithm (VBA) that can rapidly optimize rotating gantry arc angles and predict the lung V5 preceding the treatment planning. This phantom study was performed in the dynamic arc therapy planning systems for an esophageal cancer model. The angle of rotation of the gantry around the isocenter as defined as arc angle (θA), ranging from 360° to 80° with an interval of 20°, resulting in 15 different θA of treatment plans. The corresponding predicted lung V5 was calculated by the VBA, the mean lung dose, lung V5, lung V20, mean heart dose, heart V30, the spinal cord maximum dose and conformity index were assessed from dose–volume histogram in the treatment plan. Correlations between the predicted lung V5 and the dosimetric indices were evaluated using Pearson’s correlation coefficient. The results showed that the predicted lung V5 and the lung V5 in the treatment plan were positively correlated (r = 0.996, p < 0.001). As the θA decreased, lung V5, lung V20, and the mean lung dose decreased while the mean heart dose, V30 and the spinal cord maximum dose increased. The V20 and the mean lung dose also showed high correlations with the predicted lung V5 (r = 0.974, 0.999, p < 0.001). This study successfully developed an efficient VBA to rapidly calculate the θA to predict the lung V5 and reduce the lung dose, with potentials to improve the current clinical practice of dynamic arc radiotherapy.

18F-FDG PET/CT as a Potential Predictor of Lung Inflammation After Arc-Based Radiotherapy for Esophageal Cancer: A Pilot Study

“…Low-dose radiation could be a signi cant predictor of RP (14,15,30). Based on the VBA (17), the present study used the 5 Gy isodose curve to distinguish HD (≧ 5 Gy) and LD (< 5 Gy) regions in the lung volume to assess the relationship between metabolic response and absorbed dose. There were statistically signi cant increases in the SUVmax, SUVmean, and GLG of HD regions between pre-and post-RT.…”

“…According to the VBA established by our team (17), we proposed the VBA method to reduce lung V5 in dynamic arc-based RT. Therefore, we integrated the irradiated lung volume in RT planning and volumebased parameters in PET/CT.…”

“…Additionally, we proposed the volume-based algorithm (VBA) method to reduce lung V 5 by improving the arc angle in dynamic arc-based RT (17). Therefore, we aim to assess lung in ammation by integrating 18 F-FDG PET/CT with VBA before and after arc-based RT for EC.…”

Planning evaluation of a novel volume-based algorithm for personalized optimization of lung dose in VMAT for esophageal cancer

“…Before the treatment arc angle selection, the personalized OPA angle could be calculated using VBA for each patient according to Eqs. ( 1 )–( 2 ) 15 . The width of the PTV (E) was measured on the axial plane, while the axial length of the PTV (Lt) was measured vertically on the coronal image of the centroid of the PTV.…”

“…Previously, we proposed the volume-based algorithm (VBA) method to quickly calculate the optimal partial arcs (OPA) angle corresponding to the lung V 5 by defining the length and width of the planning target volume (PTV) 15 . We demonstrated that VBA could improve the efficiency of VMAT planning to reduce the lung V 5 within 5 min in a phantom study.…”