Volumetric Modulated Arc Therapy (VMAT)

Author: Courtney Misher, MPH, BS R.T.(T)
Last Reviewed: May 23, 2022

Volumetric Modulated Arc Therapy (VMAT) is a type of image-guided and intensity-modulated radiation therapy (IMRT) that become widely used in the 2000s. RapidArc is a brand of VMAT from a company that makes linear accelerators (machines used to deliver radiation). Your provider may use the names VMAT or RapidArc.

With VMAT, the beam delivering your radiation is continuously shaped by the multi-leaf collimator (MLC). The machine rotates around you and delivers your radiation. Each rotation is called an arc. Radiation can be given with one or more arcs.

How long does treatment take with VMAT?

VMAT is one of the faster ways to deliver radiation. Treatment can be given in as little as two minutes. There are two main reasons:

  • A higher dose rate (amount of radiation delivered per second) and faster gantry speed (how fast the machine rotates) are used with VMAT.
  • The machine does not have to stop and start at many different beam angles as it does with other types of radiation delivery.

How is VMAT given?

VMAT increases the number of angles that the radiation is being given from and lowers the dose of radiation to normal tissue. The beam is delivered using:

  • Image-guided radiation therapy (IGRT) to position you and the tumor.
  • Intensity-modulated radiation therapy (IMRT) to continually reshape and change the intensity of the radiation.
  • VMAT to reduce the amount of healthy tissue affected by rotating in an arc around the patient.

What type of cancers is VMAT used for?

VMAT is commonly used for tumors near critical organs. Examples are:

  • Head and neck cancers.
  • Brain tumors.
  • GI (gastrointestinal) cancers.
  • Prostate cancers.
  • Lung cancers.

What are the advantages of VMAT?

The main advantage is the amount of time it takes to deliver the radiation treatment. Other advantages include:

  • Efficient and accurate delivery.
  • Lower doses of radiation given to normal tissue.
  • Fewer side effects.

Is VMAT right for me?

There are many types of radiation therapy. Your radiation care team will consider your treatment goals, type of tumor, the shape of your tumor, and where your tumor is when deciding which type of radiation is best for you. Talk with your radiation care team about any questions or concerns you might have.


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