Intensity-modulated radiotherapy (IMRT) uses inhomogeneous radiation. This means that different radiation doses are applied at different points of the tumour. Lots of narrow tungsten strips are inserted in the head of the linear accelerator. With different shapes of radiation field and various angles of incidence, the tumour can be irradiated with great precision.
The IMRT procedure is only suitable for certain types of cancer which are located in the proximity of very sensitive organs, for example head-throat tumours or prostate cancer.
The Rapid Arc procedure is an especially fast version of IMRT. It is used under certain conditions to allow an even faster irradiation. With the "Rapid Arc", the patient only has to lie still for a few minutes.
Advantages of intensity-modulated radiotherapy:
- precise/higher dose distribution
- shorter irradiation duration
- protection of sensitive organs
Note: intensity-modulated radiotherapy is only suitable as therapy for certain types of cancer. The radiation procedure depends on where the tumour is located and which dose is required. The conventional conformal radiotherapy, which works with a homogenous dose distribution, is actually the more appropriate therapy in many cases.