Real-time image-guided radiotherapy (IGRT) with MRI could reduce healthy tissue damage and provide radiation oncologists with the capability to instantly modify treatment dose as tumors change in size and shift, according to a study published online May 19 in Physics in Medicine & Biology.

Current radiation therapy treatment damages a patient's healthy tissue as well as eradicating the tumor it is intended to destroy, making the treatment especially invasive and often causing nasty side effects.

The findings of a research group from the University Medical Centre Utrecht in the Netherlands are set to "open the door to start testing MRI-guided radiation therapy in the clinic".

The prototype is a modified 6 MV Elekta accelerator next to a modified 1.5 T Philips Healthcare Achieva MRI system. Both systems were modified to yield simultaneous and unhampered operation of the MRI and the accelerator--which is shown by performing 1.5T MRI with the beam on, the researchers wrote.

According to the results, there was no performance degradation with either system. The integrated 1.5 T MRI system and radiotherapy accelerator allow simultaneous irradiation and MRI.

By actively shielding the radiation beam from the MRI scanner's magnet and redesigning the treatment room set-up, the researchers managed to produce high-quality, real-time MRI images.

"The full diagnostic imaging capacities of the MRI can be used; and dedicated sequences for MRI-guided radiotherapy treatments will be developed. This proof of concept opens the door toward a clinical prototype to start testing MRI-guided radiation therapy in the clinic," the authors wrote.

Working towards a clinical prototype, the researchers said they hope to start the first clinical tests in one year.