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Purpose: Accurate radiation therapy (RT) for lung cancer is challenging because of the respiratory motion of the tumor and surrounding organs at risk. Recently, non-invasive mechanical ventilation (NIMV) has been investigated as a novel respiratory motion management strategy. Using NIMV, respiratory motion can be minimized, while a larger lung volume yields less overall lung dose. The purpose of this study was to determine the potential benefit of NIMV to improve lung cancer RT using magnetic resonance imaging (MRI) data of healthy volunteers., Methods and Materials: Twelve healthy volunteers practiced NIMV at 60 breaths per minute (NIMV 60 ) with added positive end-expiratory pressure (PEEP) in 2 sessions and subsequently underwent NIMV 60 in 2 MRI sessions. We acquired single-slice sagittal 2-dimensional MRI images at 2.6 Hz for 6 minutes during free breathing and NIMV 60 . We quantified the motion of all visible cross-sections of lung arteries, as a surrogate for lung tumors, in cranio-caudal and anterior-posterior directions using deformable image registration, distinguishing between 4 quadrants in the lungs (posterior-cranial, posterior-caudal, anterior-caudal, and anterior-cranial). Also, we analyzed average lung area, as a surrogate for lung volume, on the sagittal images using automatic segmentation., Results: All volunteers were successfully trained to be ventilated with NIMV 60 , and completed all sessions. The reduction of the median lung artery motion in each of the quadrants varied from 61% to 67% (from 10.7-29.9 to 3.8-11.7 mm) in cranio-caudal direction and from 51% to 68% (from 8.0-13.7 to 3.0-5.1 mm) in anterior-posterior direction using NIMV 60 . NIMV 60 increased the sagittal lung area by 35% compared with free breathing., Conclusions: NIMV 60 with added PEEP is a promising way to improve lung cancer RT because of reduced respiratory motion and increased lung area compared with free breathing., Competing Interests: Johannes Kornelis Veldman-Landegent reports financial support from Dutch Cancer Foundation (KWF). Michael J. Parkes reports financial support from Marie Sklodowska Cure Individual Fellowship. Arjan Bel reports research grants from General Electric, Varian Medical Systems Inc Elekta, and Karl Reiner. Zdenko van Kesteren reports a non-financial support from General Electric, Varian Medical Systems Inc, and Philips Healthcare. Irma van Dijk reports research grants from Varian Medical Systems Inc and Karl Reiner. The remaining authors do not have any relevant financial disclosures to report., (© 2024 The Authors.)

Purpose: Cardiac radioablation has evolved as a potential treatment modality for therapy-refractory ventricular tachycardia. To standardize cardiac radioablation treatments, promote accurate communication and target identification, and to assess toxicity, robust, and reproducible methods for angulation and cardiac segmentation are paramount. In this study, we developed and evaluated a tool for semiautomated angulation and segmentation according to the American Heart Association 17-segment model., Methods and Materials: The semiautomated angulation and segmentation of the planning-computed tomography (CT) was based on an in-house developed tool requiring placement of only 4 point-markers and a rotation matrix. For angulation, 2 markers defining the cardiac long-axis were placed: at the cardiac apex and at the center of the mitral valve. A rotation matrix was derived that angulates the CT volume, resulting in the cardiac short axis. Segmentation was subsequently performed based on marking the 2 left ventricular hinge points. To evaluate reproducibility, 5 observers independently placed markers in planning CTs of 6 patients., Results: The root mean square of the standard deviation for the angulation and segmentation marker positions were ≤0.5 cm. The 17 segments were subsequently generated and compared between the observers resulting in a median Dice coefficient of 0.8 (interquartile range: 0.70-0.87) and a median of the mean Hausdorff distance of 0.09 cm (interquartile range: 0.05-0.17). The interquartile ranges of Euler angles α and β, determined by the angulation markers, was less than 3 degrees for all patients except one. For the γ angle, determined by the hinge point markers, the interquartile range was up to 12 degrees., Conclusions: In this study a method for semiautomatic angulation and segmentation of the heart for cardiac radioablation according to the American Heart Association Segmented Model is presented and evaluated. Based on our results we believe that the segmentation is reproducible and that it can be used to promote communication between radiation oncology and cardiology, enables cardiology-oriented targeting and permits focused toxicity evaluations., (© 2022 The Authors.)