UCLA Health has been awarded a $2 million grant from ViewRay Systems, Inc. to support clinical trials focused on MRI-guided radiotherapy for cancer patients. The funding is intended to advance research into improving the accuracy of radiation treatments and reducing harm to healthy tissue during therapy.
Dr. Amar Kishan, professor and executive vice chair of radiation oncology at the David Geffen School of Medicine at UCLA and co-director of the Cancer Molecular Imaging, Nanotechnology, and Theranostics Program, described how MRI-guided radiotherapy differs from traditional methods. “MRI-guided radiotherapy is an advanced form of external beam radiotherapy that involves the utilization of magnetic resonance imaging (MRI) to guide radiation delivery. Traditionally, radiation delivery platforms have relied on X-ray-based imaging (either X-rays themselves, or computed tomography [CT] scans) to help guide radiation. MRI offers superior soft tissue imaging and contrast, and in general provides more reliable imaging in areas of the body such as the abdomen, pelvis, and central nervous system particularly. Previously, it was not possible to use MRI-based imaging to guide radiation due to potential interference between a magnetic field and the radiation delivery platform. This technical limitation has been solved with the advent of specialty linear accelerators that have integrated MRI-based imaging (MRI-LINACs).”
He also outlined advantages provided by this technology: “MRI guidance combines a 0.35T MRI with a modern linear accelerator, allowing the delivery of intensity-modulated radiotherapy (IMRT) and stereotactic body radiotherapy (SBRT). These are advanced radiation delivery techniques that use multiple beams to deliver doses precisely to pre-specified targets. The on-board MRI is helpful to target the radiation initially—as discussed above, there is improved soft tissue contrast with an MRI than a CT—but perhaps the biggest advantages are the abilities to (a) track targets in real-time and (b) perform adaptive radiotherapy.”
“For tracking, the device uses the on-board MRI to obtain images at a rate of four to eight frames per second. This generates a movie that can track the target in ‘real-time,’ with the ability to perform a ‘beam hold’ or stop the radiation if the target moves out of position. Called gating, this degree of fine motion management offers unprecedented precision.”
“Adaptive radiotherapy is a novel form of radiation therapy where a new radiation therapy plan can be generated based on daily variations in anatomy. Traditionally, the workflow of radiation involves a mapping scan (called a simulation) that is done a week or more before radiation actually starts. The radiation plan that is ultimately delivered is based off of patient anatomy at the time of the planning scan. With adaptive radiotherapy, the radiation plan is manually altered by a team of radiation oncologists, medical physicists, and dosimetrists who are working in real-time as the patient is in position, waiting for radiation to begin. This level of precision is thought to allow an increase in dose to the intended target, and a decrease in dose outside the intended target.”
Discussing results so far with this approach at UCLA Health’s program: “We have prided ourselves on cementing UCLA as a global leader in MRI-guided radiotherapy by establishing a robust clinical and research program. Our team has led multiple important studies in the field. A prominent , which demonstrated a dramatic reduction in side effects of prostate cancer SBRT with MRI-guided radiotherapy versus CT-guided radiotherapy. Another example is , which showed benefit of MRI-guided radiotherapy in post-prostatectomy treatment context.” Dr. Kishan also noted UCLA’s leadership role for “the SMART trial,” which evaluated adaptive SBRT for pancreatic cancer.
The current focus includes trials targeting prostate cancer as well as gastrointestinal malignancies such as colorectal and pancreatic cancers; gynecological cancers; and sarcomas.
Ongoing studies include:
– HEATWAVE: “triple precision” therapy for intermediate risk prostate cancer
– MASAMUNE: adaptive post-prostatectomy SBRT
– HERA: adaptive post-operative treatment for gynecological malignancies
– NOM-Rectal: short-course non-surgical rectal cancer therapy
– MARS: short-course abdominopelvic sarcoma therapy
Planned randomized trials include MANTICORE for prostate cancer adaptive therapy evaluation and VORTEX assessing neurovascular-sparing approaches.
Dr. Kishan explained why this technology addresses key challenges: “A fundamental challenge in radiation oncology is that efficacy and safety…relies on our ability to visualize targets…Just as surgeons would never operate without visualizing their target…combining enhanced spatial contrast from MRIs with real-time tracking improves precision.” He added their data already show reduced side effects using aggressive margin reduction enabled by real-time tracking during prostate SBRT.
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