Intensity Modulated Radiotherapy (IMRT)

What is IMRT?
How does IMRT work?
What are the risks and benefits of this therapy?

What is IMRT?
Intensity modulated radiotherapy (IMRT) is an advanced external radiation therapy used to treat tumours in the body. A tumour is an irregularly-shaped malignant growth located amidst other normal, vital body parts. Radiation is generally used in cancer treatment to control the growth and spread of the disease, or to cure the disease by completely eliminating the growth of cancerous cells.

IMRT allows radiotherapists to “sculpt" the radiation beams to the specific shape and contour of a tumour, sparing the adjacent healthy tissue from unnecessary radiation exposure.

How does IMRT work?
With the aid of images taken with computed tomography (CT scans) or positron emission tomography/CT (PET/CT scans), IMRT allows physicians and therapists to deliver a very precise radiation beam to the active cancerous site.

A radiotherapist uses these three-dimensional computerized scans to visually chart the location of the tumour and surrounding healthy tissue. Once charted, specially-trained physicists use virtual reality simulation to plot a radiation treatment targeting the exact shape of the tumour. An optimal treatment plan can require hours of very careful calculations.

Once the target is plotted, the treatment plan information is then input electronically to a linear accelerator, the machine used to deliver radiation treatments. Radiation beams are delivered in approximately 300 different segments, focusing the radiation on the tumour while minimizing the dose passing through normal tissue.

What are the risks and benefits of this therapy?
Standard radiotherapy affects both cancerous and normal surrounding tissue, causing side effects such as severe diarrhoea, abdominal pain, and mouth and throat ulcers. With IMRT technology, patients experience significantly lower treatment-related side effects. IMRT also offers the potential for higher cure rates and shorter healing times.