Image-Guided Radiation Therapy (IGRT)

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

What is IGRT?
Similar to IMRT and based on similar technology, image-guided radiotherapy (IGRT) is a state-of-the-art external radiation therapy used to treat cancerous tumours in the body.

How does IGRT work?
In standard IMRT, CT scans or PET/CT scans record static, or still, images of the body, which are used to locate tumours, help develop a radiation treatment plan, and guide the radiation beams during treatment. The great advantage of IMRT over other radiation therapies is that the radiation beam can be shaped to match the dimensions of a tumour, which means that higher doses of radiation can be delivered to the tumour without harming the surrounding normal tissue.

However, due to normal body movements, such as breathing and digestion, tumours can move slightly in the body, both during a radiation treatment session and also between treatment sessions. If these changes in position move the tumour out of the planned range of the radiation beam, the tumour may not receive the full amount of radiation that it should, or normal tissues may receive more radiation than they ideally should.

In IGRT, new patient-positioning techniques and complex computing and imaging technology are used to take patient motion or tumour movement into account during radiation treatment, thereby delivering an even more effective radiation beam to the tumour in real time.

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

Doctors and researchers expect that patients with cancers of the lung, breast, liver, and other abdominal and pelvic cancers — those areas of the body which have the potential to move most with each breathing cycle — will benefit greatly from the highly targeted technique of IGRT.