Michael T Prusator1, Pamela Samson2, Jochen Cammin3, Clifford Robinson2, Phillip Cuculich4, Nels C Knutson2, S Murty Goddu2, Kaitlin Moore4, Geoffrey D Hugo2. 1. Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri. Electronic address: m.prusator@wustl.edu. 2. Department of Radiation Oncology, Washington University School of Medicine in St. Louis, St. Louis, Missouri. 3. Department of Radiation Oncology, University of Maryland, Baltimore, Maryland. 4. Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri.
Abstract
PURPOSE: Noninvasive cardiac radioablation is increasingly used for treatment of refractory ventricular tachycardia. Attempts to limit normal tissue exposure are important, including managing motion of the target. An interplay between cardiac and respiratory motion exists for cardiac radioablation, which has not been studied in depth. The objectives of this study were to estimate target motion during abdominal compression free breathing (ACFB) and respiratory gated (RG) deliveries and to investigate the quality of either implanted cardioverter defibrillator lead tip or the diaphragm as a gating surrogate. METHODS AND MATERIALS: Eleven patients underwent computed tomography (CT) simulation with an ACFB 4-dimensional CT (r4DCT) and an exhale breath-hold cardiac 4D-CT (c4DCT). The target, implanted cardioverter defibrillator lead tip and diaphragm trajectories were measured for each patient on the r4DCT and c4DCT using rigid registration of each 4D phase to the reference (0%) phase. Motion ranges for ACFB and exhale (40%-60%) RG delivery were estimated from the target trajectories. Surrogate quality was estimated as the correlation with the target motion magnitudes. RESULTS: Mean (range) target motion across patients from r4DCT was as follows: left/right (LR), 3.9 (1.7-6.9); anteroposterior (AP), 4.1 (2.2-5.4); and superoinferior (SI), 4.7 (2.2-7.9) mm. Mean (range) target motion from c4DCT was as follows: LR, 3.4 (1.0-4.8); AP, 4.3 (2.6-6.5); and SI, 4.1 (1.4-8.0) mm. For an ACFB, treatment required mean (range) margins to be 4.5 (3.1-6.9) LR, 4.8 (3-6.5) AP, and 5.5 (2.3-8.0) mm SI. For RG, mean (range) internal target volume motion would be 3.6 (1.1-4.8) mm LR, 4.3 (2.6-6.5) mm AP, and 4.2 (2.2-8.0) mm SI. The motion correlations between the surrogates and target showed a high level of interpatient variability. CONCLUSIONS: In ACFB patients, a simulated exhale-gated approach did not lead to large projected improvements in margin reduction. Furthermore, the variable correlation between readily available gating surrogates could mitigate any potential advantage to gating and should be evaluated on a patient-specific basis.
PURPOSE: Noninvasive cardiac radioablation is increasingly used for treatment of refractory ventricular tachycardia. Attempts to limit normal tissue exposure are important, including managing motion of the target. An interplay between cardiac and respiratory motion exists for cardiac radioablation, which has not been studied in depth. The objectives of this study were to estimate target motion during abdominal compression free breathing (ACFB) and respiratory gated (RG) deliveries and to investigate the quality of either implanted cardioverter defibrillator lead tip or the diaphragm as a gating surrogate. METHODS AND MATERIALS: Eleven patients underwent computed tomography (CT) simulation with an ACFB 4-dimensional CT (r4DCT) and an exhale breath-hold cardiac 4D-CT (c4DCT). The target, implanted cardioverter defibrillator lead tip and diaphragm trajectories were measured for each patient on the r4DCT and c4DCT using rigid registration of each 4D phase to the reference (0%) phase. Motion ranges for ACFB and exhale (40%-60%) RG delivery were estimated from the target trajectories. Surrogate quality was estimated as the correlation with the target motion magnitudes. RESULTS: Mean (range) target motion across patients from r4DCT was as follows: left/right (LR), 3.9 (1.7-6.9); anteroposterior (AP), 4.1 (2.2-5.4); and superoinferior (SI), 4.7 (2.2-7.9) mm. Mean (range) target motion from c4DCT was as follows: LR, 3.4 (1.0-4.8); AP, 4.3 (2.6-6.5); and SI, 4.1 (1.4-8.0) mm. For an ACFB, treatment required mean (range) margins to be 4.5 (3.1-6.9) LR, 4.8 (3-6.5) AP, and 5.5 (2.3-8.0) mm SI. For RG, mean (range) internal target volume motion would be 3.6 (1.1-4.8) mm LR, 4.3 (2.6-6.5) mm AP, and 4.2 (2.2-8.0) mm SI. The motion correlations between the surrogates and target showed a high level of interpatient variability. CONCLUSIONS: In ACFB patients, a simulated exhale-gated approach did not lead to large projected improvements in margin reduction. Furthermore, the variable correlation between readily available gating surrogates could mitigate any potential advantage to gating and should be evaluated on a patient-specific basis.
Authors: Rosalind Perrin; Patrick Maguire; Adriano Garonna; Georg Weidlich; Shelley Bulling; Marie Fargier-Voiron; Cedric De Marco; Eleonora Rossi; Mario Ciocca; Viviana Vitolo; Alfredo Mirandola Journal: Front Cardiovasc Med Date: 2022-05-04