Doctors have been making videos using CT scanners built into radiation therapy machines for some time already. However, CT scans do not reveal (tumours in) soft tissues very well. For patients with liver cancer, for instance, doctors therefore have to insert small rods to use as visible markers. These markers enable them to see which area to target with radiation therapy.
'The 3D MRI video means that we don't need markers anymore,' explains radiotherapist Edwin Jansen, who treated the first patient. This is because the MRI scan can reveal the location of the metastasis within the liver. 'That's good news because inserting the markers can be a nasty procedure for patients. It can be painful and they can suffer from infections or bleeding.'
Another important advantage is that the 3D MRI video enables doctors to see the tumour as it moves, rather than just the markers. They can see exactly which position the tumour is in as the patient breathes. 'This way, we can see even better where we need to focus the radiation,' explains Jansen. 'We hope this will enable us to irradiate even more accurately than we already do. That will reduce the chance of side effects and it may also enable us to increase the radiation dose if necessary.'
Making a 3D MRI video involves quite a bit more work than making a video on your mobile phone. The MRI scanner makes 750 2D scans of the tumour over a period of 5 minutes. Using the new software developed at the Netherlands Cancer Institute, a computer can then merge all the scans into a 3D video that shows the movement of the tumour as the patient breathes. Tessa van de Lindt spent four years of PhD research on developing this new technique.
The first patient to be treated using a 3D MRI video is participating in a clinical trial that will show whether it is technically feasible to treat all patients with limited liver metastases using this new method from now on. Radiotherapists call these video's 4D MRI's. Marlies Nowee, radiotherapist and leading the research project, explains: 'We are treating patients using this new radiotherapy technique for the first time in this trial. If everything goes well in the first group of patients, we may offer the treatment to more patients. We won't need to insert markers any more, that's already a real benefit for patients.'
The doctors at the Netherlands Cancer Institute are currently only using this new technique to treat patients with limited liver metastases. Later, they hope to extend the treatment to tumours in other organs that move during radiation therapy. Cancer patients with extensive metastases usually receive systemic therapy such as chemotherapy or immunotherapy. But if there are only a limited number of metastases, localised treatment through surgery or radiation therapy may be an option. Doctors decide which treatment is the most suitable for a patient at a multidisciplinary meeting, where they take into account more than just the number of metastases.
- The Netherlands Cancer Institute has become the first in Europe to administer radiation therapy to a cancer patient using a 3D MRI video. This technique reduces the invasiveness of the required treatment, and it enables doctors to see the movement of a tumour just before radiation therapy is administered so that they can take the movement into account while planning the treatment.
- The new technique is currently only being used as part of a trial involving a small group of patients with limited liver metastases. The trial will reveal whether the technique is technically feasible.
- For more information about this treatment, please contact: +31 (0)20 512 9111 (ask for the Patient Information Centre)