Elekta, the famous Swedish maker of radiation therapy, radiosurgery, and brachytherapy systems, is in the final stages of combining a linear accelerator therapy and magnetic resonance imaging scanner in one unified system. Many physicists and engineers thought that this would be impossible, as quickly moving charged particles shooting out of an accelerator are strongly affected by a magnetic field. But scientists at UMC Utrecht, a major research center in Holland, had some novel ideas and built the first prototype long ago, proving the skeptics wrong, and in the process convincing Elekta to work with Philips on developing a commercial MR-linac machine.
The new Elekta Unity MR-linac relies on a Philips 1.5 Tesla MRI machine, which produces diagnostic level image quality during therapy sessions. This it is hoped will allow for more precise treatment, including higher doses targeting sensitive areas containing multiple organs, and immediate observation of how the tumor is being affected by the radiation. Previous systems relied on low-field MR, which is not sufficient to produce crisp, easy to analyze images.
We spoke with Richard Hausmann, the CEO of Elekta, to learn more about this revolutionary new system. He explained that an MR-linac resembles a traditional cathode ray tube (CRT) television in which electrons are directed at different parts of the screen by changing the strength of the magnetic fields they fly through. While this technique helps to produce an image on a CRT TV, a magnet near a highly focused electron beam bends it in unwanted directions. It took quite a bit of engineering and calculating to align various components to effectively minimize the effect of the magnet on the electron beam.
One particularly useful expected capability of the Unity is functional MRI (fMRI), which permits the observation of how the treatment is affecting the state of the tumor. Essentially blood flow through the tumor can be evaluated, which indicates whether the tissue is still alive and well or has succumbed to the therapy. Though this is expected to be available on the Unity, Hausmann believes it’ll take a bit of time for technicians to get acquainted with using the feature and to learn to apply it in different circumstances.
Therapy sessions last about 30 to 45 minutes, not much longer than traditional linac treatments, but re-planning based on concurrent imaging may be required, leading to longer sessions. Mr. Hausmann assured us that workflows have been designed to make re-planning quick and easy, keeping treatment times close to what they are on existing linacs.
The investigational system is already installed in six different institutions in the U.S. and Europe and a number of studies have already produced plenty of results.
Here’s a promo video from Elekta about the new Unity MR-linac:
Product page: Elekta Unity MR-linac…