SEOUL NATIONAL UNIVERSITY HOSPITAL

- ViewRay visualizes and tracks tumor location and shapes using a state-of-art magnetic resonance (MR) imaging technology and deliver high-precision image-guided radiation therapy (IGRT).
- SNUH is the 4th center that operates ViewRay system in the Word (first center outside the United States).




Seoul National University Hospital installed the state-of-the-art radiation therapy system, ViewRay. SNUH is the first center that operates ViewRay system to treat cancer patients outside the United States. ViewRay features an integrated MR imaging system that allows for high-resolution visualization of tumors and adjacent normal organs. Combining two cutting-edge technologies, a real-time MR imaging and advanced intensity-modulated radiation therapy (IMRT) system, ViewRay provides high-precision IGRT. Currently, ViewRay is the only device capable of MR-guided IMRT.

So far, conventional IGRT has largely depended on X-ray-based imaging like computed tomography (CT). The shape and location of tumors and internal normal organs are subject to continuous changes due to various physiological causes such as breathing, stomach filling or emptying, gut peristalsis and so on. Conventional methods of IGRT have limitations in obtaining real-time anatomical information regarding tumors and adjacent normal organ.  It has ben impossible to obtain detailed sectional images of patients while radiation is “on”, that is, being delivered. To account for uncertainty related to internal movement of tumors, doctors prescribe radiation doses to a larger volume including adjacent normal tissues as well as tumors. At the cost of radiation exposure of normal organs, this method ensures that tumors receive intended radiation doses in spite of internal movement.

ViewRay is a game changer in tackling this problem. ViewRay is the first IMRT machine fully integrated with MR imaging devices. Its real-time cine MRI capability allows for obtaining MR images during radiation is “on”. By “tracking” tumors throughout a whole radiation therapy session, ViewRay allow doctors to reduce unintended radiation exposure to adjacent normal tissues. ViewRay uses high-resolution MR images for treatment planning and daily patient set up. Daily MRI provides unique opportunity that physicians detect any significant changes in tumors and normal organs and adapt treatment plans accordingly. ViewRays’s strength in adaptive radiation therapy is that it can obtain as many daily MR images as needed without exposing patients to additional radiation doses. Most conventional IGRT methods use X-ray, thus delivering non-therapeutic radiation doses to patients.

So far, ViewRay is operational only in SNUH and three hospitals in the United States (Barnes Jewish Hospital, UCLA Medical Center Hospital, University of Wisconsin Carbone Cancer Center). Hong-Gyun Wu, Chair of Department of Radiation Oncology, says, “So far, IGRT has had limitations that we don’t know what is going on within patients’ body while radiation is “on”. Thanks to ViewRay’s real-time cine MR imaging technology, we now have IGRT capability to let us be able to see and track tumors in a truly real-time fashion. ViewRay also provides IMRT. Combining the best of both worlds, I hope that ViewRay will help us provide quality IGRT. By solving long-standing unmet needs in radiation therapy, I anticipate that ViewRay benefits many patients and their caregivers”. The first ViewRay treatment in SNUH has been successfully completed for metastatic liver cancer. Now, application of ViewRay in SNUH has extended to various sites such as lung, breast, liver, abdomen and prostate.