Imaging and Plan Workflow in a Novel Low-Field Magnetic Resonance Imaging (MRI) Radiotherapy Device

Recently, Viewray Inc (Cleveland, OH) has released the RenaissanceTM System 1000, which
consists of the combination of an open, split solenoid 0.35 T MRI scanner that is equipped
for parallel imaging with a 60Co gamma-ray radiation treatment unit. The MRI scanner is
required to be a low field unit to allow for imaging with spatial integrity by limiting
magnetic susceptibility artifacts due to the patient and to prevent significant
perturbations of the dose distribution. The 0.35 T magnet is a variant of the Siemens
MAGNETOM product used for intraoperative imaging.

A previous study of pilot imaging using this device without the 60Co sources was completed
in 2012 (HRPO# 201105295). In this study, a total of 26 patients were imaged with the
device. Fourteen of these patients also had onboard CT imaging (OB-CT) where the two sets of
imaging and relative organs at risk (OARs) could be compared. Fifteen to 24 OARs were
evaluated per anatomical site. In total, 221 OARs and 10 target structures were compared for
visualization on MRI and OB-CT image sets by each physician. At least 2/3 physicians
evaluated MRI as offering better visualization for 71% of structures, OB-CT offering better
visualization for 10% of structures, and both offering equivalent visualization for 14% of
structures. Physicians agreed unanimously for 74% and in majority for >99% of structures
evaluated, respectively. For <1% of structures, no consensus was reached. Targets were
better visualized on MRI in 4/10 cases, and were never better visualized on OB-CT images.

There were limitations to this prior study. The patients were not imaged in immobilization
devices that are commonly used in radiation therapy. This precluded the creation of a mock
radiation therapy plan using the device for these patients. Also, the device was not
evaluated in the context of radiation therapy decision making, such as patient shifts,
target localization and patient repositioning.

The purpose of this study is to evaluate the imaging and plan workflow for radiation therapy
utilizing this novel device. For this protocol, only the MRI scanner of the machine will be
utilized. The 60Co portion of the machine capable of radiation treatment administration will
not be utilized, and there will be no experimental treatments or modifications to each
patient's standard of care radiation treatment plan.

Eligibility Criteria:

- Scheduled to receive radiation therapy.

- At least 18 years of age.

- Does not meet any standard contraindications for MRI (such as being claustrophobic,
having metal objects within the body that cannot be removed or having large tattoos),
confirmed by completion of our clinical MRI questionnaire form

- Able to understand and willing to sign an IRB approved written informed consent
document.