Hybrid Linac-MRI System developed by University of Alberta

Scientists of Cross Cancer Institute at the University of Alberta, USA are developing a breakthrough hybrid Linac-MR system that integrates two existing medical devices—medical linear accelerators, or ‘linacs’, and Magnetic Resonance Imagers (MRIs). Linacs are used to produce powerful X-rays for treating cancer and MRIs are used for imaging tumours in the human body.

The system allows doctors to accurately monitor moving tumours in lungs and other soft tissues such as the liver or prostate in real time during the radiation treatment. Determining the exact location and shape of a tumour measures the success of modern cancer radiotherapy.

Hybrid Linac-MR has been introduced to overcome problems of not giving true image-based guidance of the entire volume of the tumor by existing Image-Guided Radiation Treatment techniques. Linacs use radio waves to accelerate electrons to high speeds and crash them into a solid metal target—typically tungsten, producing high-energy X-rays in the collision. These high-energy X-rays destroy cancerous cells by causing irreparable damage to the cells' DNA; MRIs are very effective at imaging soft tissue and are an ideal technology for combining with Linacs as most cancers occur in soft tissue. The problem is making MRIs and Linacs work together as one interferes with the other.

Scientists have managed to build a prototype Linac-MR device that overcomes the obstacles of placing both instruments Linac system and MRI together in the same room. It has a specialised design that shields the radio frequency waves and magnetic fields and works by taking MRI test images with the Linac (both on and off mode) to demonstrate that the interference is eliminated.