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MRI linac at U Virginia or Philadelphia and my Florida experience
Prostate Cancer | Last Active: Nov 25, 2025 | Replies (13)Comment receiving replies
@erbill and @brianjarvis : I was treated with the MRIdian in February 2023 at the Orlando Health cancer center. Yes Viewray went bankrupt but service contracts for $1m/year were available through another company that hired some of the original people from Viewray. Orlando Cancer center has indicated that they are not satisfied with the service they get for $1m and are going to switch to the Elekta Unity but that takes about a year. In the meantime, they are still using it for Prostate cancer but it seems that they try to prioritize what kind of cancer they use it for and organ movement is one criteria for that decision. I ran into that type of prioritization with Moffitt when I was looking for treatment at facilities that had the MRIdian and in Moffitts case, I was told by an executive radiologist that if I wanted the adaptive dynamic capability of the machine, to go elsewhere so I did.
The Elekta unity has some similar functions to the MRIdian, gating and adaptive functionality, but I am not familiar with other features , other than a higher Tesla, that gives it an advantage over the MRIdian.
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I wondered the same regarding the magnet strength of the MRIdian and this what found when I was going for my 5 treatments….. The ViewRay MRIdian system uses a 0.35 Tesla (T) magnet to achieve high-quality images and specific advantages for radiation therapy.
Here's why ViewRay opted for this field strength:
Optimal field strength for radiation therapy: The 0.35 T magnet allows the system to avoid image artifacts and distortions in the dose distribution that can occur with high field strength magnets.
Geometrically precise images: This low field strength leads to geometrically precise images, without susceptibility distortions or chemical-shift artifacts.
Accurate dose distributions: The precise images enable accurate dose distributions for treatment.
Reduced tissue heating: The lower radiofrequency (RF) excitation frequency at 0.35 T minimizes RF induced tissue heating, allowing for uninterrupted MR imaging during treatment.
Split superconducting magnet design: The split superconducting magnet at 0.35 T allows for an unobstructed beam path, addressing technical complexities of combining an MRI with a linear accelerator.
Reduced magnetic susceptibility artifact: This low field strength reduces artifacts caused by spinal hardware and other materials, improving visualization of targets and organs at risk (OARs).
In essence, the 0.35 T magnet on the MRIdian is chosen to optimize image quality and treatment delivery in the context of MR-guided radiation therapy.