Volumetric Modulated Arc Therapy (VMAT)

Volumetric modulated arc therapy (VMAT) is a new technology designed to deliver treatment quickly and accurately. If appropriate for the treatment of your cancer, it can reduce the number of visits and shorten recovery time.

During treatment the patient lies on a padded bench specially fitted to the machine. A large barrel shape delivers the radiation sweeping in uninterrupted arcs. Although the movement may seem random it is carefully planned. Using 3D imaging your radiation therapist is able to ‘see’ the tumour during your treatment and target it directly.

In more detail

VMAT works by delivering single or multiple radiation beams in continuous sweeping arcs around the patient.

The arcing movement of the radiation means the shape and intensity of the beams change as the machine rotates. This reduces the dose of radiation to the normal tissue while focussing the dose on the cancer.

This delivers fast and accurate treatment and significantly improves recovery time. It also allows tumors to be treated that are near critical structures in the body. In cases where a tumour is wrapped around an organ, VMAT can accurately target the tumour while minimising damage to the organ.

Key benefits of VMAT:

  • Reduces treatment time to as little as two minutes. Compared to more conventional radiation therapies this may be six to ten minutes less per treatment session.
  • Provides the radiation oncologist with more accuracy and control during treatment. It also provides information to determine the optimal dose to deliver in each case.
  • Maximises the radiation dose to the target while minimising exposure to surrounding healthy tissues. VMAT is often useful for treating cancers in delicate areas such as the breast, prostate and lung.

Intensity Modulated Radiation Therapy (IMRT) is another type of highly accurate radiation therapy. IMRT shapes the radiation beams closely around the tumour. This means the dose conforms precisely to the three-dimensional shape of the tumour. By adjusting the intensity of the radiation beam in multiple small volumes, higher radiation doses can be focused to regions within the tumour while minimising the dose to the surrounding healthy tissues. IMRT also reduces the risk of long-term side effects and protects important areas like the spinal cord or salivary glands.

Treatment is carefully planned using CT scans and computerised dose calculations. Due to the complexity of the system, IMRT requires additional planning time and safety checks.  It also requires longer daily treatment times. 

IMRT is used to treat many different types of tumour. It is used extensively to treat cancers of the prostate, head and neck, and central nervous system. Read more about the use of IMRT for the treatment of Head and Neck cancers by clicking on the links below.

Head and neck cancer responded well to IMRT  Study finds more targeted form of radiation improves survival in patients with head and neck cancers

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