Volumetric Modulated Arc Therapy (VMAT) is a type of external beam radiation therapy used to treat cancer. In this method, a specialized machine delivers radiation beams to destroy tumors without touching the patient’s body. VMAT is a more advanced technology in which the machine rotates around the patient while they lie down, continuously delivering radiation precisely targeted at the tumor. Since the radiation source is not placed inside the body, patients do not become radioactive during or after treatment.
VMAT is also part of Intensity-Modulated Radiation Therapy (IMRT), a technique that allows doctors to adjust radiation doses with high precision. With this technology, high doses of radiation can be focused directly on the tumor while surrounding healthy tissues are protected from excessive exposure. During a VMAT procedure, patients receive radiation doses tailored to their specific condition, while the machine rotates around the body in one or more arcs to ensure effective and accurate treatment.
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When Is VMAT Used?
The precision in dose adjustment and radiation delivery makes VMAT an excellent option for treating irregularly shaped tumors or tumors located close to vital organs. For example, an oncologist may recommend VMAT if a tumor surrounds or is very near an important organ.
VMAT is commonly used to treat prostate cancer, head and neck cancers, and lung cancer. It can also be used for various other types of cancer, including:
- Anal cancer
- Brain cancer
- Breast cancer
- Cervical cancer
- Colorectal cancer
- Esophageal cancer
- Lung cancer
- Nasopharyngeal cancer
- Oropharyngeal cancer
- And many other types of cancer.
How Does VMAT Work?
VMAT works by delivering the maximum radiation dose directly to the cancerous tumor while minimizing damage to surrounding healthy tissue. As the machine rotates around the patient’s body, the shape and intensity of the radiation beams are continuously adjusted to precisely target the tumor. The high-dose radiation damages the DNA of cancer cells, preventing them from growing and ultimately causing them to die.
1. Before the Procedure
Before treatment begins, the medical team carefully plans the therapy. Patients usually undergo imaging tests such as CT scans, MRI, and/or PET scans to create three-dimensional (3D) images of the body. These images help doctors accurately identify the tumor’s location and determine which nearby organs need protection from radiation exposure.
The doctor then calculates the radiation dose required to effectively destroy the tumor.
Patients will also attend a planning session called a simulation (“sim”). During this session, they are positioned on a treatment table and aligned with the LINAC machine (radiation machine) to ensure that the radiation beams will precisely target the tumor during actual treatment.
At this stage, patients may receive:
- Special markings on the body (temporary or permanent, such as a small tattoo) to indicate the tumor’s location.
- Support devices such as body molds or masks to help keep the body in a stable position during treatment.
The simulation may be completed in one visit or multiple visits, depending on the case. VMAT technology allows radiation beams to be extremely small—approximately 2.5 x 5 millimeters (about the size of a pencil tip)—making the treatment highly precise.
2. What Happens During the VMAT Procedure?
On the day of treatment, a radiation therapist will position the patient exactly as during the simulation session. The LINAC machine is operated from a separate room, but patients can communicate with staff through a two-way microphone.
During therapy, the machine slowly rotates around the patient’s body. Radiation beams of varying shapes and intensities are directed at the tumor. Patients do not feel the radiation beams. The radiation therapist monitors the treatment in real time to ensure the correct dose is delivered to the precise location.
Typically, one or two rotations of the machine are sufficient to deliver a full radiation dose for a session.
How Long Does a VMAT Procedure Take?
A single VMAT session generally lasts about 20 minutes. Most of that time is spent positioning the patient accurately. The actual radiation delivery usually takes only about two minutes.
Depending on the type and stage of cancer, patients may need daily VMAT sessions for several weeks. The treatment schedule will be determined by the oncologist based on the patient’s condition.
After each session, patients can go home the same day and resume normal activities as advised by their doctor.
What Are the Advantages of VMAT?
The main advantages of VMAT are its precision and speed.
- Precision: VMAT accurately focuses radiation on the tumor while minimizing exposure to surrounding healthy tissues.
- Speed: Each VMAT session typically takes around two minutes or even less. Shorter treatment times improve the accuracy of radiation delivery, reduce the time patients must remain still, and make the overall treatment process more efficient.
If you would like to consult about VMAT or other cancer treatments, you can use the WhatsApp Chat feature, Book Appointment service, or download the Care Dokter application on Google Play and the App Store to schedule visits, check queue numbers, and access other complete information.
