Simulated Online Adaptive Magnetic Resonance–Guided Stereotactic Body Radiation Therapy for the Treatment of Oligometastatic Disease of the Abdomen and Central Thorax: Characterization of Potential Advantages

• Published in: International journal of radiation oncology, biology, physics Vol. 96; no. 5; pp. 1078 - 1086
• Main Authors: Henke, Lauren, Kashani, Rojano, Yang, Deshan, Zhao, Tianyu, Green, Olga, Olsen, Lindsey, Rodriguez, Vivian, Wooten, H. Omar, Li, H. Harold, Hu, Yanle, Bradley, Jeffrey, Robinson, Clifford, Parikh, Parag, Michalski, Jeff, Mutic, Sasa, Olsen, Jeffrey R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2016
• Subjects: ABDOMEN; Abdominal Neoplasms - diagnostic imaging; Abdominal Neoplasms - pathology; Abdominal Neoplasms - radiotherapy; Abdominal Neoplasms - secondary; Aged; Aged, 80 and over; ANATOMY; BIOMEDICAL RADIOGRAPHY; CHEST; CLINICAL TRIALS; COMPUTERIZED TOMOGRAPHY; Duodenum - diagnostic imaging; GY RANGE 10-100; Hematology, Oncology and Palliative Medicine; Humans; LIVER; Magnetic Resonance Imaging, Interventional - methods; Middle Aged; NEOPLASMS; Organs at Risk - diagnostic imaging; RADIATION HAZARDS; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; Radiosurgery - methods; RADIOTHERAPY; Radiotherapy Dosage; Radiotherapy Planning, Computer-Assisted - methods; SIMULATION; Stomach - diagnostic imaging; Thoracic Neoplasms - diagnostic imaging; Thoracic Neoplasms - pathology; Thoracic Neoplasms - radiotherapy; Thoracic Neoplasms - secondary; Tomography, X-Ray Computed - methods
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2016.08.036

To characterize potential advantages of online-adaptive magnetic resonance (MR)-guided stereotactic body radiation therapy (SBRT) to treat oligometastatic disease of the non-liver abdomen and central thorax. Ten patients treated with RT for unresectable primary or oligometastatic disease of the non-liver abdomen (n=5) or central thorax (n=5) underwent imaging throughout treatment on a clinical MR image guided RT system. The SBRT plans were created on the basis of tumor/organ at risk (OAR) anatomy at initial computed tomography simulation (PI), and simulated adaptive plans were created on the basis of observed MR image set tumor/OAR “anatomy of the day” (PA). Each PA was planned under workflow constraints to simulate online-adaptive RT. Prescribed dose was 50 Gy/5 fractions, with goal coverage of 95% planning target volume (PTV) by 95% of the prescription, subject to hard OAR constraints. The PI was applied to each MR dataset and compared with PA to evaluate changes in dose delivered to tumor/OARs, with dose escalation when possible. Hard OAR constraints were met for all PIs based on anatomy from initial computed tomography simulation, and all PAs based on anatomy from each daily MR image set. Application of the PI to anatomy of the day caused OAR constraint violation in 19 of 30 cases. Adaptive planning increased PTV coverage in 21 of 30 cases, including 14 cases in which hard OAR constraints were violated by the nonadaptive plan. For 9 PA cases, decreased PTV coverage was required to meet hard OAR constraints that would have been violated in a nonadaptive setting. Online-adaptive MRI-guided SBRT may allow PTV dose escalation and/or simultaneous OAR sparing compared with nonadaptive SBRT. A prospective clinical trial is underway at our institution to evaluate clinical outcomes of this technique.