ViewRay has received FDA premarket notification clearance for its MRI-guided radiation therapy system. The ViewRay system features a unique combination of radiotherapy delivery and simultaneous magnetic resonance imaging (MRI) for the treatment of cancer, providing continuous soft-tissue imaging during treatment so that clinicians can see and record precisely where radiation therapy is being delivered, as it is being delivered.
Radiation therapy treatment plans are based on previously acquired static imaging such as CT or PET/CT. Motion correction has historically been done with markers applied to the body and more recently with image-guided radiation therapy, where CT scans or X-rays are acquired moments before the initiation of radiotherapy. These systems, however, have the disadvantage of introducing an additional radiation dose and not being able to visualize the tumor in real-time.
By using real-time MRI, the Viewray system shows soft-tissue as it is being treated and adjusts for its movement in real time, without using any additional radiation. Radiotherapy is only delivered when the system detects that the target tissue is within the radiation target area. In addition, it helps clinicians keeping track of the delivered dose of radiation to avoid normal tissues and critical structures such as the spinal cord by allowing for on-the-fly treatment plan re-optimization.
The ViewRay system is primarily intended for treatment of tumors that are likely to move significantly during treatment. This includes thoracic, abdominal and pelvic malignancies, such as lung, prostate, liver and head and neck cancer. ViewRay’s corresponding treatment planning and delivery software already received FDA premarket notification clearance in 2011.
The first ViewRay system is installed at the Siteman Cancer Center at Barnes‐Jewish Hospital and Washington University School of Medicine, where early imaging studies have taken place. Additional ViewRay partners include the UCLA Jonsson Comprehensive Cancer Center and the University of Wisconsin Carbone Cancer Center, where a ViewRay system is currently being installed.