Clinical Factors That Affect Fiducial Tracking in Robotic SABR for Lung Tumors

BackgroundStereotactic ablative radiotherapy (SABR) is a treatment option for patients with lung tumors that employs fiducials to track during the breathing cycle. Currently, there paucity of data on how relative fiducial location and patient clinical characteristics impact tracking outcomes. This study aims identify factors reduce number tracked respiratory motion management SABR.MethodsAn IRB approved retrospective review was performed receiving robotic SABR at our institution from 2016 2019. Clinical including demographics, medical history, follow up were collected. Fiducials geometries obtained Velocity contouring software MATLAB. Chi-Square, t-test, Mann-Whitney-U tests completed using MedCalc.Results73 77 treatments identified. Chi-Square analysis revealed chronic obstructive pulmonary disease (COPD) associated having Three or more (p=0.034). Tumors in lower lobes higher rates uncertainty errors (p=0.015). The had no local tumor control overall survival median 36 month up. 28 centroid available geometric analysis. most common rigid body error (RBE) (57%) spacing (36.4%). Spacing shorter average minimum inter-fiducial distance versus non-spacing (1.0 cm vs 1.7 cm, respectively, p = 0.017). RBE longer maximum non-RBE (4.0 3.0 0.022).ConclusionGreater can contribute certain prevent being tracked. Maintaining between experimentally determined guidelines may limit RBE's, two errors. Increased set result stronger correlations