• Question: Can u give a explation to the MRI radiotherapy machine? It sounds intresting

    Asked by anon-292584 to Rosie on 26 Apr 2021.
    • Photo: Rosie Goodburn

      Rosie Goodburn answered on 26 Apr 2021: last edited 26 Apr 2021 11:14 am

      Hi! An MRI radiotherapy machine combines an MRI scanner and a radiotherapy “Linac”. Linacs are what we normally use to give patients radiation treatment for cancer. The patient lies on a bed and a big rotating arm can shoot beams of radiation at their tumour from many different angles. A team of scientists and doctors carefully plan the positions and angles of the radiation beams for every patient so we can optimise where the radiation will go – as little as possible to healthy tissue and as much as we can to tumours.
      .
      The MRI radiotherapy machine (or “MR-Linac”) has both an MRI scanner and a Linac built-in! The normal tunnel of an MRI scanner is there, but we had to put a gap in the middle so the Linac can shoot the radiation through it. The radiation treatment part is also built onto a giant rotating ring rather than the more simple rotating arm used for normal Linacs. There is a good picture on my profile if you’d like to see a diagram!

Comments

  • Photo: Ed

    Ed commented on :

    In radiotherapy they use a picture to plan the radiation. On the day the patient turns up for there radiotherapy they take another picture to make sure the ‘target’ hasn’t moved. Normally the picture is a CT scan (like a 3D x-ray). But for some things MRI shows the anatomy more clearly so they are developing MRI – radiotherapy where the picture they take to check the ‘target’ hasn’t moved is an MRI scan. This is of benefit for treating prostate cancer, as if the patient drinks too much or too little water before their scan the position of the prostate can move quite a lot.

  • Photo: Rosie

    Rosie commented on :

    Thanks Ed! It’s true 🙂 In my PhD, I’m working on making fake CT scans from the MRI scans. This is useful because CTs (or 3D X-rays, like Ed said) tell us how dense everything is, and that is useful to calculate how radiation will interact in the body and where it will end up.
    .
    So if we put a patient on an MR-Linac, we can:
    1) See their organs really well with the MRI pictures right before we treat them
    2) Use the fake-CTs to make a new plan for where the radiation will go in the body. And we can change the positions and angles of the beams of radiation to adapt to all the latest positions of the patient’s organs and bones 🙂