2513 - Variation in Treatment Time and On-Board Imaging for Lung Tumors by Motion Management Technique: A Secondary Analysis of the iSABR Trial
Presenter(s)
J. E. Worth1, J. A. Jaoude2, M. J. Campbell1, I. O. Romero3, N. Kastelowitz4, P. Dubrowski5, D. Pham6, L. Skinner7, A. L. Chin8, M. F. Gensheimer4, M. Diehn7, B. W. Loo Jr1, and L. Vitzthum6; 1Stanford University, Palo Alto, CA, 2Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 3Stanford University School of Medicine, Palo Alto, CA, 4Department of Radiation Oncology, Stanford University School of Medicine, Stanford, CA, 5Department of Radiation Oncology, Stanford University School of Medicine, Palo Alto, CA, 6Department of Radiation Oncology, Stanford University, Stanford, CA, 7Department of Radiation Oncology, Stanford University, Palo Alto, CA, 8Stanford University School of Medicine, Stanford, CA
Purpose/Objective(s): Multiple techniques have been developed for addressing intra-fraction motion during stereotactic ablative radiation therapy (SABR) for lung tumors. Data comparing these approaches, however, are limited. In addition to local control and toxicity outcomes, patient treatment time and the amount of kilovoltage (kV) required to complete treatment are clinically relevant, patient-centered outcomes worthy of consideration. The purpose of this analysis is to evaluate differences in total treatment time and amount of kV imaging required to complete treatment by motion management technique.
Materials/Methods: We conducted a secondary analysis of patients treated on the multicenter phase II iSABR clinical trial, which utilized an individualized dosing strategy for patients with primary or metastatic lung tumors. Motion management approach was determined by the treating provider in each case. We collected data on radiation treatment delivery parameters, including the number of kV, cone-beam CT (CBCT), or fluoroscopy imaging sessions, as well as treatment time. Differences in treatment time and imaging were compared across motion management techniques including: inspiratory breath hold (IBH), expiratory gating (EG), motion inclusive (MI), or no motion management. One-way analysis of variance (ANOVA) was conducted to compare differences in imaging sessions, treatment setup time, and total session time between the motion management techniques. Multivariable linear regression was performed to assess predictors of total session time when accounting for additional patient and tumor factors.
Results: A total of 255 patients with 276 tumors treated on iSABR were included in our analysis. Sixty-one tumors (22.1%) were treated with IBH, 67 tumors (24.2%) with EG, 34 tumors (12.3%) with MI, and 114 tumors (41.3%) with no motion management. Patients treated with IBH had the highest median number of CBCT scans (median: 3, interquartile range [IQR]: 2-3) and kV imaging (median: 2, IQR: 1-3), while patients treated without motion management had the fewest CBCT scans (median: 1, IQR: 1-1, p < 0.001) and KV imaging (median: 1, IQR: 1-1, p = 0.035). Radiation treatment setup time and total session time were longest for IBH (mean: 33.5, 38.1 minutes, respectively) followed by EG (mean: 25.26, 31.7 minutes, respectively), MI (mean, 19.8, 22.9 minutes, respectively), and no motion management (mean: 13.4, 15.7 minutes, respectively) (p < 0.001). Multivariable analysis identified IBH and EG as significant predictors of longer treatment session times (p < 0.001).
Conclusion: In this secondary analysis of patients treated on the iSABR trial, there was significant variation in treatment time and imaging requirements by motion management strategy. IBH was associated with the longest treatment times and the most kV imaging.