Study reveals high accuracy of MR-guided radiotherapy for intracranial itereotactic radiosurgery

A new study, led by radiation oncology physicists at Miami Cancer Institute, part of Baptist Health South Florida, displayed positive results using intracranial stereotactic radiosurgery, also known as SRS, for an MR-guided radiotherapy system. The study, ‘Commissioning Intracranial Stereotactic Radiosurgery (SRS) for an MR-guided Radiotherapy (MRgRT) system: MR-RT Localization and Dosimetric End-to-End Validation’ published in the International Journal of Radiation Oncology – Biology – Physics (IJROBP), highlights positive accuracy through an end-to-end hidden target test to quantify the imaging, planning, and delivery coincidence of an MR Linac system, ViewRay MRIdian.

Kathryn Mittauer, Ph.D., lead physicist for the MR-guided radiation therapy program with Miami Cancer Institute, was the first author of this study. Mittauer explains the team developed an in-house MR head phantom to simulate stereotactic radiosurgery for brain tumors. Specifically, the study simulated intracranial spherical targets, an irregularly shaped target, and a target abutting brainstem.  

Nema Bassiri, Ph.D., radiation oncology physicist with Miami Cancer Institute, and senior author of this study, explains that this delivery was successful with up to 99% accuracy. Bassiri adds that “this work enables the utilization of novel MR-guided radiotherapy technology for intracranial SRS, which has not been used with MR Linac systems.” MRI is the gold standard to evaluate and localize brain tumors due to soft tissue visualization capabilities.

“Since we demonstrated the accuracy of ViewRay MRIdian’s capability to deliver within a 1 mm setup margin in this work, we have now deployed this novel technique to our brain cancer patients at Miami Cancer Institute”, adds Mittauer. The team has observed that the volume of a patient’s tumor change during a 3-fraction radiosurgery course through using the onboard MR image guidance of the MR Linac system.

“What’s most impressive is that we are able to visualize how the tumor volume changes day to day, even throughout a short 3-fraction treatment. This research will help us better understand how these tumors change (including tumor progression), and the role of adaptive radiotherapy which adjusts the radiation to account for these changes to enable more precision”, shared Mittauer. “In the field of radiation oncology, this is revolutionary as we assess the frequency of these anatomical changes and how this will inform us for even other radiation choices.”

“In the future, we will see more studies that investigate the benefit of using MRIdian for stereotactic radiosurgery. This study will help advance the community by providing a blueprint to implement MR-guided SRS program for anyone who is interested in utilizing this treatment technique”, shared Bassiri.

The full study can be found here.

About Miami Cancer Institute

Miami Cancer Institute brings to South Florida access to personalized clinical treatments and comprehensive support services delivered with unparalleled compassion. No other cancer program in the region has the combination of cancer-fighting expertise and advanced technology—including the first proton therapy center in South Florida, Latin America and the Caribbean, and one of the only radiation oncology programs in the world with each of the newest radiation therapies in one place—to diagnose and deliver precise cancer treatments that achieve the best outcomes and improve the lives of cancer patients. The Institute offers an impressive roster of established community oncologists and renowned experts, clinical researchers and genomic scientists recruited from the nation’s top cancer centers. Selected as Florida’s only member of the Memorial Sloan Kettering Cancer (MSK) Alliance, Miami Cancer Institute is part of a meaningful clinical collaboration that affords patients in South Florida access to innovative treatments and ensures that the standards of care developed by their multidisciplinary disease management teams match those at MSK. For more information, please visit https://cancer.baptisthealth.net/miami-cancer-institute.

Miami Cancer Institute is part of Baptist Health Cancer Care, the largest cancer program in South Florida, with locations from the Florida Keys to the Palm Beaches.

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