Stereotactic radiosurgery

Overview
Stereotactic radiosurgery is a form of non-surgical radiation therapy. Different types of equipment are available to deliver stereotactic radiosurgery. The Gamma Knife is technology designed specifically for brain treatments. It has the strongest track record (evidence-base) in its field, it has a key advantage of high precision.
Stereotactic treatment, such as Gamma Knife radiosurgery, operates on the principles of stereotaxy to guide three-dimensional radiation beams to a set target in the brain.
Each beam has a low energy, but where the beams join (converge) on the target, they collectively give the therapeutic dose that is needed.
The higher the number of these three-dimensional beams, the greater the precision. The Gamma Knife has up to 200 beams – setting it apart in its field.
Unique feature of Gamma Knife radiosurgery
Each low energy radiation beam has a minimal effect on surrounding tissue in the brain as it passes onto the target point in the brain where all the beams converge (come together).
The Gamma Knife’s unique capability means that it has what is called a rapid radiation dose fall off so there is minimal damage to healthy surrounding brain tissue.
Key aspects
Stereotactic radiosurgery relies on:
01.
Three-dimensional imaging and localisation techniques to determine the exact coordinates of the target in the brain.
02.
Systems to immobilise and position the patient and maintain his or her position during treatment.
03.
Highly focused gamma beams that converge on a tumour or abnormality.
04.
Image-guided radiation therapy which uses medical imaging to confirm the location of a tumour before – and sometimes during – the radiosurgery, thereby improving the precision and accuracy of the treatment.
Damages DNA of targeted cells
Stereotactic radiosurgery works by creating harmful free radicals (molecules) which damage the target cells in the brain, including their DNA. The dose of radiation is measured in grays (Gy).
Enabling system
The system that enables Gamma Knife surgery to accurately concentrate the beams on the target in the brain is made up of:
- A radiation unit
- Beam-focusing technology
- A patient couch
- An electric bed system
- A control console and
- A computer system.
The sophisticated computerised treatment planning software coordinates all this technology to spare as much healthy brain tissue as is possible.
Stereotactic head frame
- Sets a reference coordinate map that allows points in the brain to be located with high precision and then
- Attaches to the couch to hold the head in place to ensure the beams are on target.
Target determination
Target determination is informed by x-ray images obtained using stereotactic computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), magnetoencephalography, or cerebral angiography.
Proven alternative treatment
Stereotactic radiosurgery provides patients with an alternative to more invasive surgery and is particularly useful in cases with tumours and abnormalities that are:
- Hard to reach or
- Situated close to vital structures.
Gamma Knife radiosurgery is offered by the Gamma Knife South Africa team as an alternative, minimally invasive therapy in managing patients with tumours, vascular malformations and other abnormalities in the brain.
As science and techniques evolve, craniopharyngiomas, pineal region tumours, uveal melanomas and patients with other movement disorders are increasingly being treated using stereotactic radiosurgery.
View: Leksell Gamma Knife Icon – the ultimate solution for cranial radiosurgery