What is stereotactic radiosurgery?
Despite its name, stereotactic radiosurgery (SRS) is a non-surgical radiation therapy to treat abnormalities and small tumours in the brain.
Stereotactic radiosurgery help in directing precisely-targeted radiation to the affected area than in traditional therapy. This ensures minimal or no damage to the healthy tissues around the affected area.
Stereotactic radiosurgery is possible thanks to significant advances in radiation technologies. This form of radiosurgery ensures a powerful radiation dose aimed accurately at the target area, and minimizing radiation dosage and damage to the adjacent healthy tissue. The aim is to deliver doses that destroy the tumour and not the surrounding tissues.
Use of stereotactic radiosurgery:
- Used in three-dimensional imaging such as CT, MRI, and PET/CT. This locates the tumour or abnormality within the body and details its exact size and shape. These images also guide in the precise treatment.
- Radiation beams are designed to converge on the target area from different angles and planes, with a patient is carefully positioned during the radiation therapy sessions.
- SRS is used as an important alternative to invasive surgery, more so for patients unable to undergo surgery for the following reasons: the tumour is hard to reach, located close to vital organs/anatomic regions, have a high risk of complications post-surgery.
- Used in the treatment of many types of brain tumours.
- Used to treat other neurological conditions such as trigeminal neuralgia (a nerve disorder in the face), tremor, etc.
How does stereotactic radiosurgery work:
Stereotactic radiosurgery essentially works in a manner similar to other methods of radiation treatment: it does not actually remove the tumour but disrupts the DNA of tumour cells. This results in these troublesome tumour cells losing their ability to reproduce.
After treatment, benign tumours shrink over a period of 18 months to two years. Malignant and metastatic tumours may reduce more rapidly, even within a couple of months. Arteriovenous malformations (AVMs) may take a period of several years following treatment.
Many tumours will remain stable and inactive but this is no problem – the objective is achieved since the aim is to prevent tumour growth.
In tumours like acoustic neuromas, a temporary enlargement may be observed following SRS. This is due to inflammation within the tumour tissue, but it soon stabilizes.
Radiosurgery can also be done using the Linear Accelerator (LINAC) SRS, which is similar to the Gamma Knife procedure. But unlike the Gamma Knife – which remains motionless during the procedure – a part of the LINAC machine (called a gantry) rotates around the patient and shoots accurate radiation beams from different angles.
Stereotactic radiosurgery team:
The Stereotactic radiosurgery therapy team has many medical specialists, including a neurosurgeon, radiation oncologist, radiologist, radiation therapist, medical radiation physicist, dosimetrist and radiation therapy nurse.
The radiation oncologist or a neurosurgeon leads the team and oversees the treatment. They outline the target(s) for the treatment, decide on the radiation dose, finalize the treatment strategy and interpret results of radiological procedures.
A neurologist or neuro-oncologist may work with the radiation oncologist and neurosurgeon to consider the treatment options customized for the specific patient. They help decide if the patient can benefit from radiosurgery for lesions in the brain.
Side effects can occur due to the treatment itself, and from radiation damage to healthy cells in the treatment area.
Early side effects after radiation therapy can include tiredness or fatigue and skin problems. The skin in the treatment area may become extra sensitive, red, irritated, or swollen; there may be dryness, itching, peeling and blistering.
Other early side effects (depending on the treatment location in the body) may include:
- Hair loss in the treatment area
- Soreness and swelling in the treatment area
- Mouth problems and difficulty swallowing
- Eating and digestion problems
- Urinary and bladder changes
- Nausea and vomiting
Side effects usually disappear within a few weeks. Late side effects are rare but can appear months or even years later. They include changes in the brain, spinal cord, lungs, kidney, colon and rectal. Late side effects can also lead to secondary cancer, infertility, damages to the joints, and bone fracture.
A slight risk exists of developing cancer from radiation therapy. A cancer patient receiving radiation treatment is advised to regularly consult the radiation oncologist. This precaution is necessary to ensure there is no recurring of cancer or new cancers.