MR Linac (Magnetic Resonance Linear Accelerator). Dr Aznar

MRL Linac Definition:

An MR Linac is a hybrid medical device that combines a linear accelerator (linac) — which delivers high-energy X-rays for radiation therapy — with a magnetic resonance imaging (MRI) system, allowing for real-time, high-contrast imaging of soft tissues during radiation treatment.

 

Key Features:

  • Enables MRI-guided radiotherapy, offering real-time visualization of tumors and surrounding tissues.
  • Enhances treatment precision and adaptability, especially for tumors that move (e.g., due to breathing or organ motion).
  • Supports adaptive radiotherapy, allowing clinicians to adjust the radiation plan on the spot based on daily changes in patient anatomy.

Here are the main clinical advantages of using an MR Linac over conventional linear accelerators:

 

  1. Real-Time Soft Tissue Visualization
    • MRI offers superior soft tissue contrast compared to CT or X-ray imaging.
    • Tumors and surrounding organs (e.g. pancreas, liver, prostate) can be clearly seen during treatment.
    • Helps reduce margins, leading to less radiation to healthy tissue.
  2. Adaptive Radiotherapy
    • MR Linacs allow daily adaptation of the treatment plan based on anatomical changes (tumor size/position, organ movement, etc.).
    • Improves accuracy and effectiveness, especially for tumors that change shape or position.
  1. Continuous Tumor Tracking
    • Some systems enable real-time motion tracking and even automatic beam gating (pausing the beam when the target moves out of position).
    • Especially valuable for mobile tumors (e.g. lung, liver, prostate).
  1. Reduced Toxicity
    • By targeting the tumor more precisely and sparing healthy tissues, MR Linacs may reduce side effects and toxicity.
    • Allows for higher radiation doses (dose escalation) in some cases, improving tumor control.

5. Improved Outcomes for Complex Cases

    • Particularly beneficial for tumors located near critical structures (e.g. spinal cord, bowel, bladder).
    • Opens up treatment options for previously untreatable or high-risk cases.