Magnetic Resonance Imaging – Linear Accelerator (MRI-LINAC, UNITY®)
On December 24, 2019, the Faculty of Medicine Siriraj Hospital, Mahidol University, is the first in Southeast Asia and the only hospital in Thailand to install the UNITY® 1.5T MRI 7MV-Linear accelerator for clinical use in radiation therapy and research program.
Linear accelerator (LINAC) is the major modality used in radiotherapy, delivering high-energy photon (x-ray or gamma-ray) to kill cancer cells directly. The standard LINAC is usually equipped with onboard kilovoltage (kV) imaging and/or low-resolution cone-beam computer tomography (CBCT) to help with patient alignment and optimal tumor localization before initiation of each treatment fraction. The limited quality of CBCT is problematic, especially for a hard-to-see deep-seated tumor.
MRI-LINAC is a ground-breaking linear accelerator system equipped with a fully integrated diagnostic 1.5 Tesla MRI scanner, enabling real-time diagnostic-grade visualization of the tumor and surrounding normal organs before, during, and after radiation therapy, without any extra radiation dose.
Why should we prefer the UNITY® MRI-LINAC over the conventional LINAC system?
The cutting-edge technology of the fully integrated MRI with real-time on-board imaging is superior to CBCT for its precise localization of the tumor whereabouts, correction for internal target and organ motion, and adaptation for daily anatomical changes, such as respiratory motion, bowel gas movement, or bladder filling. With this information, radiation treatment is adapted daily in real-time, delivering higher radiation dose to cancer, in turn, enhancing and maximizing tumor control, at the same time, minimizing radiation dose to normal organ to reduce any long-term side effect, all with less than 15 minutes’ period of on-board adaptation. The system, combined with a computerized multi-leaf collimator, allows tracking of tumor targets for exceptionally accurate radiation delivery for moving tumor targets. To date, the MRI LINAC is the best-in-class of the truly personalized real-time adaptive precision radiotherapy system in the world.
What is the role of treatment with the UNITY® MRI-LINAC at Siriraj hospital?
The UNITY® MRI-LINAC promises that one can visualize all anatomical changes during the course of radiotherapy and hence the optimal treatment from adaptive planning, especially prostate cancer, bladder cancer, gynecologic malignancy, and head and neck cancer. Siriraj radiation oncology team expects that the MRI-LINAC will enhance and maximize tumor control to benefit Thai cancer patients. Furthermore, advance Thailand as the lead researcher for precision cancer radiotherapy by MRI.