Intensity-Modulated Radiation Therapy (IMRT)

What is intensity-modulated radiation therapy (IMRT)?
Intensity-modulated radiation therapy (IMRT) is a type of radiotherapy that makes use of linear accelerators, which are controlled by computers. The linear accelerators are devices that are designed to deliver very accurate and precise doses of radiation for the treatment of tumours. During IMRT treatment, the radiation conforms to the size and shape of the tumour, and the dose of radiation is delivered in varying intensity, depending on the area that is being targeted. This means that the radiation is focused on the tumour with extreme precision, with minimal damage to surrounding healthy tissues.

How does it work?
IMRT is most commonly used for the treatment of prostate, head and neck cancer and can be useful at any site where the tumour is of an irregular shape or lies close to normal tissues. Before the treatment begins, it is carefully planned with the use of 3D CT and MRI scans. These images allow your oncologist to determine the optimal radiation dose for the exact size and shape of the tumour.

The treatment works by preventing cancerous cells from dividing and growing, in turn slowing down or inhibiting the growth of tumours. In some cases, the therapy is successful in completely destroying cancer cells and eliminating whole tumours.

Your oncologist will position you comfortably on the treatment table. Imaging tests may be used to help ensure that your position is correct before treatment begins. The linear accelerator (also known as LINAC) is used to deliver radiation beams to the area of the tumour from various different angles. Depending on your treatment plan, the intensity of the beams will be adjusted according to the area that is targeted.

Are there any side-effects?

The treatment is painless, and you should not feel any discomfort during the session. Some patients experience radiation side-effects after the treatment, including hair loss, digestive problems, headaches, nausea, vomiting, swelling in the treatment area, and urinary and bladder changes.