SRS – Stereotactic Radiosurgery for Brain Lesions

Tumors can occur anywhere in the body, including the brain. Brain tumors can be either benign (non-cancerous) or malignant (cancerous). Both types can cause symptoms and affect your quality of life. In some cases, tumors may be dangerous to your health depending on the location. Stereotactic Radiosurgery (SRS) is a type of radiation therapy that treats brain lesions.

What is Stereotactic Radiosurgery?

Stereotactic radiosurgery (SRS) is a highly accurate form of radiation therapy that targets brain or spinal tumors, as well as other abnormalities in the brain. SRS may also treat brain metastases. Brain metastases are cancer cells which originate in other parts of the body, but have spread to the brain.

SRS works in much the same way as other types of radiotherapy. Radiation damages the DNA of cancerous cells, preventing them from reproducing and spreading. Radiation can also damage the DNA of healthy cells, which is why thorough planning is important.

Image courtesy of NCI, Daniel Sone (photographer).

Stereotactic radiosurgery can treat:

• Arteriovenous malformations (AVMs)
• Base of skull tumors
• Benign brain tumors
• Trigeminal neuralgia
• Pituitary tumors
• Primary malignant brain tumors
• Metastatic brain tumors
• Spinal tumors
• Spinal Radiosurgery currently in progress

SRS generally requires fewer treatments than traditional radiation therapy, and in most cases can be performed in one day.

How Does Stereotactic Radiosurgery Work?

Stereotactic Radiosurgery (SRS) is a multi-part process. Thorough planning is necessary prior to treatment.

Tumor Imaging

The tumor first must be scanned using 3-D imaging techniques such as CT, MRI, or PET/CT. Imaging provides details such as the height, shape, and exact location of the tumor. This information helps your radiation oncologist and in most cases neurosurgeon assess the dose and treatment method to use.

Accurate images also help ensure accurate treatment with minimal damage to surrounding tissue.

Treatment Planning

Once information about the tumor has been obtained, your radiation oncologist will work with a team of radiation specialists to plan your entire treatment.

Treatment Planning Includes:

• Determining the total dose needed to treat the tumor
• Determining the angles of radiation beams as well as the exact dose of each beam
• Calibrating the Linear Accelerator
• Placing your head frame

Since SRS usually treats brain, neck, and head tumors, your radiation oncologist may take a multidisciplinary approach. He or she may work in conjunction with a neurosurgeon, neurologist, neuroradiologist, or neuro-opthamologist. Your radiation oncologist will determine the best treatment option for you.

Patient Positioning

The exact positioning of the patient for each treatment session is crucial. Stereotactic radiosurgery (SRS) requires the use of a head frame, also known as a stereotactic ring, to immobilize the patient during treatment.

What to Expect During SRS Treatment:

• Treatments generally last 30 minutes – 1 hour.
• The SRS treatment is painless, so you will not feel any discomfort.
• During treatment, your radiation therapist will be in a nearby room controlling the treatment machine. They will be in contact with you through microphones and speakers.
• Narrow beams of radiation are aimed at the tumor from varying pre-set angles. The individual beams do not have a significant effect on healthy tissue. The intersection of the beams, however, provides a targeted dose of radiation.

SRS treatments may take place in a single session or multiple sessions depending on the size and location of the tumor.

There are 3 Types of SRS Treatment Methods:

• Linear Accelerator: A Linear Accelerator uses X-rays to treat cancerous and noncancerous tumors in the brain and other parts of the body. Stereotactic Radiosurgery (SRS) may be performed in one session, while Stereotactic radiotherapy (SRT) may take place over multiple sessions.
• Gamma Knife: A Gamma Knife uses 192 or 201 beams of radiation, each at different angles, to treat small to medium brain tumors and other brain lesions. These tumors may be cancerous or noncancerous. The Gamma Knife is limited to single-dose stereotactic radiosurgery (SRS) only.
• Proton Beam (Heavy Charged Particle Radiosurgery): Proton Beam therapy is a form of radiation therapy that uses a beam of particles called protons instead of X-rays. This type of therapy is new to the US and not yet common. Proton Beam therapy may take place as single-session stereotactic radiosurgery (SRS), or in multiple sessions as stereotactic radiotherapy (SRT).

Stereotactic Radiosurgery is painless and noninvasive whether a Linear Accelerator or Gamma Knife is used. Unlike traditional surgery, SRS poses no risk of infections, hemorrhage, or other surgery-related complications.

Side Effects of Stereotactic Radiosurgery

Stereotactic radiosurgery (SRS) tends to have fewer side effects due to the precision of beam delivery. In addition, the treatment sites in SRS are smaller and less healthy tissue comes into contact with the radiation.

Not every patient experiences side effects, but many patients feel tired following treatment. Most side effects of SRS are caused by brain swelling (edema).

Side Effects From Stereotactic Radiosurgery Include:

• Fatigue
• Nausea
• Vomiting
• Dizziness
• Headache
• Necrosis
• Seizures (rare)

At Blue Ridge Radiation Oncology, our treatment team is happy to answer any questions you may have about short term and long term side effects of stereotactic radiosurgery.