Stereotactic Radiosurgery

What is stereotactic radiosurgery?

Stereotactic radiosurgery (SRS) is a very precise form of radiation therapy that uses multiple radiation beams to treat abnormalities in the brain and spine.

Unlike traditional surgery, SRS does not involve making an incision or opening in the body. Guided by 3D imaging, high doses of radiation are directed to the target area with minimal impact on the surrounding healthy tissue.

Because SRS delivers radiation at much higher doses with greater precision, it requires only a single or fewer (usually 3 - 5) treatments than traditional radiation therapy.

How it works

During the procedure, the radiation beams are aimed at the tumour from many different points, which allows for a more accurate delivery of radiation.

It is usually given in 6 – 25 doses called fractions. A single fraction of this therapy is called radiosurgery.

Stereotactic radiosurgery works just like other forms of radiation by destroying or damaging the targeted cells' DNA. This affects the abnormal cells' reproduction ability, causing these tumors to become inactive and shrink.

What is the difference between stereotactic radiosurgery and stereotactic radiotherapy?

The difference between stereotactic radiosurgery and stereotactic radiotherapy has to do with the intensity and duration of the radiation treatments.

In stereotactic radiosurgery, radiation is delivered at a very high intensity, in one single dose, to a small area.

In stereotactic radiotherapy, radiation is delivered at different times, at lower intensities to larger areas. This allows the healthy tissues time to recover between treatment sessions.

What is the difference between stereotactic radiosurgery and gamma knife radiosurgery?

Gamma knife radiosurgery is also a form of stereotactic radiosurgery but specifically treats conditions of the brain and head. Like other forms of SRS, there is no incision but uses specialised equipment to focus tiny beams of radiation on the targeted area.

Gamma knife radiosurgery is usually a one-time therapy completed in a single day.

Why do you need stereotactic radiosurgery?

Stereotactic radiosurgery is used to treat neurological conditions such as:

• Acoustic neuroma, a non-cancerous tumour at the base of the skull base which can affect your hearing and sense of balance. SRS is used to stop its growth or minimise its size to prevent permanent nerve damage.
• Epilepsy. SRS uses many precisely focused radiation beams to treat the area of the brain where seizures begin with minimal impact on the surrounding healthy tissue. If a brain lesion such as a tumour causes epilepsy, treating it may decrease the chance of it happening.
• Trigeminal neuralgia, a chronic condition which affects the trigeminal nerves and causes extreme facial pain. The nerves are responsible for relaying sensory information between your brain and areas of your forehead, cheek and lower jaw. SRS targets the trigeminal nerve root to disrupt these pain signals.

Stereotactic radiosurgery offers the following benefits:

• Your surgeon is able to access the deepest parts of the brain not treatable with conventional surgery
• As there is no incision, the patient experience minimal discomfort and little surgical risks
• Patients only require lightly sedation and are able to stay awake throughout the procedure
• Majority of patients are treated on an outpatient basis, or require an overnight stay at most
• Patients experience less discomfort and have much shorter recovery periods than with conventional surgery

What are the risks and complications of stereotactic radiosurgery?

Stereotactic radiosurgery is generally less risky than traditional surgery as there are no incisions or cutting.

Any early complications or side effects are usually temporary. In rare cases, people may experience belated side effects. This may occur months after treatment and varies depending on the body site.

Anti-inflammatory medications (corticosteroid medications) may be prescribed to prevent such problems or to treat symptoms if they appear.

Your doctor will discuss the potential risks more thoroughly with you.

Early complications or side effects will depend on which part of your body is treated. They include:

• Tiredness and fatigue in the first few days after the procedure
• Swelling at or near the treatment site, which can cause a temporary increase in pain
• Nausea or vomiting, if the radiated tumor is near the bowel or liver
• Hair loss in the treatment area
• Mouth problems and swallowing difficulties
• Eating and digestion problems
• Diarrhoea
• Nausea and vomiting
• Headaches
• Soreness and swelling in the treatment area
• Urinary and bladder changes

Belated side effects may include:

• Bowel changes
• Changes in the lungs
• Changes in the spinal cord
• Developing a new cancer (secondary cancer)
• Swollen arms and legs (lymphedema)
• Weakened or brittle bones

How do you prepare for stereotactic radiosurgery?

Depending on the condition and body area being treated, preparation requirements may differ. It may involve the following:

• Abstaining from food or drink after midnight the night before the procedure
• Checking with your doctor about when you should take your regular medications
• Wearing comfortable, loose-fitting clothing
• If you are undergoing the procedure on your spine, avoid wearing:
  • Contact lenses
  • Dentures
  • Jewellery
  • Make-up
  • Nail polish
  • Spectacles
  • Wigs or hairpieces

Note: Let your doctor know if you have an implanted medical device in your body, such as a pacemaker, artificial heart valve or stent.

What can you expect in stereotactic radiosurgery?

Stereotactic radiosurgery is usually an outpatient treatment.

Estimated duration

The procedure lasts about 20 – 60 minutes.

Before the procedure

Inform your doctor if you have claustrophobia. Preparation for the procedure involves several steps:

• A small metal marker about the size of a grain of rice is placed in or near the tumour.
• Your doctor will conduct a simulation to determine the best placement of your body to align it with the radiation beams. An immobilisation device will be used to hold your body still. Imaging scans will be taken. You may be asked to hold your breath for 10 – 30 seconds to reduce any movement.
• With the aid of specialised software and the imaging scans, your doctor will plan your treatment and determine the best combination of radiation beams to target your tumour.

During the procedure

Children are often anaesthetised for the imaging tests and during the radiosurgery. Adults do not need to be anaesthetised. If you're feeling anxious, your doctor may give you a mild sedative to help you relax.

The machine moves and rotates around the target during treatment to deliver radiation beams from different angles.

During the procedure, you will not be able to feel the radiation and you will be able to communicate with your doctor via a microphone.

After the procedure

You will be able to eat and drink after the procedure. You can expect to go home on the same day.

You can resume your normal activities within 1 – 2 days.

Inform your doctor if you experience symptoms such as pain or nausea. Your doctor will prescribe you appropriate medications.