Last Friday the first patient (first-in-man) from a series of five was treated at the University Medical Center (UMC) Utrecht using the so-called MRI-Linac, the latest radiotherapy machine. This machine renders tumors crystal clear during treatment. This precise and up-to-date visual information allows tumors to be radiated with surgical precision and minimum damage to surrounding tissue, even if a tumor moves during treatment. The MRI-Linac has been developed by Prof. Dr. Jan Lagendijk, Professor of Clinical Physics, and Prof. Dr. Bas Raaymakers, Professor of Experimental Clinical Physics.

As early as 1999 Lagendijk thought it should be possible to combine a linear accelerator (which is the radiation device) and MRI machine into one machine to be able to help patients better and faster. An impossible undertaking, everyone in the radiotherapy world thought, because linear accelerators (often metal) and MRI (highly magnetic field) are normally incompatible. However, Lagendijk and Raaymakers stubbornly carried on. There is now an international consortium of seven renowned institutes, with Elekta and Philips as industrial partners, that have adopted the Utrecht-born development. In recent months, a large team from the UMC Utrecht consisting of physicians, physicists, laboratory assistants and technicians did everything they could to be able to finally treat a patient safely and very accurately after 18 years.

Change of treatment plan
The MRI-Linac creates “live” 1.5T MRI images of tumors before and during radiation, which makes this an exceptionally accurate treatment. "In the patient with the MRI-Linac we demonstrated that we're able to demonstrate the dose within 1% and with 0.3mm accuracy. This allows us to keep damage to healthy tissue to a minimum," says Lagendijk. "Moreover, we can change the treatment while the patient is lying in the machine. This means that we're treating the anatomy as is," Raaymakers adds. Until now, this was impossible, although it is highly desirable as a tumor can change in form and volume or move the surrounding organs.

The study at the UMC Utrecht has now reached the stage where five patients with bone metastases are radiated in an initial study. These tumors can be seen in so-called bundle photos, allowing the accuracy of the MRI-controlled treatment to be effectively evaluated.

If this initial clinical study is a success, the UMC Utrecht will start a follow-up study with patients with tumors in the abdomen and pelvis.  These patients will be the first to benefit from the MRI-Linac. Head researcher from the UMC Utrecht, Dr. Ina Jürgenliemk-Schulz, Radiotherapeutic Oncologist, explains,  "We can radiate tumors directly, with a higher dose if necessary, without causing unnecessary damage to the surrounding healthy tissue." It will probably also be possible to increase the daily dose, reducing the number of hospital visits for patients.