The Stereotactic Radiosurgery Unit at Prince of Wales Hospital began patient treatment in 1990, making it the most experienced clinical service in Australia with over 350 patients treated by Stereotactic Radiosurgery to date. In addition fractionated Stereotactic Radiotherapy has been in regular use for two years. The most advanced computer planning programs are available to ensure accuracy and safety of treatment.

Many lesions or tumours within the brain are not suitable for treatment by surgery. Features that determine this include: the site, including proximity to important brain structures; previous treatment given; and patient preference for non surgical treatment. Stereotactic Radiation Treatment relies upon precisely locating the lesion in the brain with exact coordinates (similar to latitude and longitude), and aiming at that target. This treatment can be given as:-

· Stereotactic Radiosurgery (SRS) - a single high dose of radiation is given, the procedure being done in one day. This is suitable for vascular malformations, benign tumours and cancer matasteses, where the target (lesion) is less than 3 cm in size and is away from important structures such as visual (optic) nerves.

· Stereotactic Radiotherapy (SRT) - this gives the radiation treatment over many days (fractions)usually 5-6 weeks. This procedure allows larger lesions (up to 5 cm in size) and those close to important structures to be treated.

Benefits:

· Non invasive - no surgery is involved, the only component passing into the brain is the invisible X-ray beam.

· Convenience - typically done as day only or out patient procedures, with all patients, other than children, wide awake during the procedure.

· Results - in most situations comparable to surgery. Can even be used where previous radiotherapy has been given.

· Safety - although risks of serious damage exist, these are usually less than 5%. Allows much lower dose of radiation to be given to the surrounding brain.

· Recovery - return to work or normal life function is the norm a few days after SRS, or continuing during SRT.

Disadvantages:

The time to benefit can take weeks to months but without progression of the lesion during that time.

The Procedure:

· Consultation and Acceptance for treatment - Not all patients are suitable for treatment. The radiological images, (scans, etc) will be evaluated by members of our Radiosurgery Team and the decision made for SRS or SRT.

· Pre-Treatment Imaging - most patients treatment is planned with a Magnetic Resonance Imaging (MRI) scan. A brief scan (7-10 mins) is done a few days prior to the treatment.

· Frame Fixation - treatment relies upon developing co-ordinates, used to define exactly where the lesion and important brain structures are, from a metal ring reference plane around the head.

SRS - after insertion of a local anaesthetic into the skin, the frame is attached to the skull bone, remaining there usually for 6-8 hours.

SRT - dental impressions and back of head individual moulds are taken that allow for accurate replacement of the head ring on a daily basis - this may require 2-3 fittings over a period of 5 days before planning.

· Treatment Imaging - with the head ring on, a CT scan is performed enabling us to determine the exact co-ordinates. Some patients having SRS will also require an angiogram to be performed.

· Planning - sophisticated software programmes on advanced hardware computer platforms allow 3-D visual graphics to be displayed on the computer screen, to determine the best way to treat the target. This is akin to the flight simulation programmes that major airline pilots perform frequently.

· Treatment - this is a short component of the procedure usually only taking 20-40 minutes. The head of the Linear Accelerator (LINAC) moves across the patient’s head while the invisible, silent X-Ray beam zeros in on the target. Treatment is divided into a number of segments with the patient couch being moved to a different position for each segment.

· Completion - after the treatment the head ring is taken off, by unscrewing the pins for SRS and detaching the dental plate for SRT, the patient is usually able to go home with very low likelihood of immediate side effects.

· Quality Assurance - multiple checks take place throughout each step of the procedure to ensure the accuracy, including verifying the head ring has not moved.

· Follow Up - can usually be done by referring specialist. This ranges from doing serial blood tests for patient with hormone active pituitary tumours, to scans for tumours and angiograms for vascular malformations.

· Comparison - the Gamma Knife is one method of treatment by SRS, as is the use of Protons from a Cyclotron. In this unit we use a LINAC to provide the X-Ray beam. In terms of results, there is little difference to choose between the three methods, a LINAC having the advantage of providing treatment by SRT.

Research:

An ongoing active research programme exists to better refine the treatment both in terms of effectiveness as well as in terms of safety, with presentations of our results being made at national as well as international meetings. A contribution towards this research would be much appreciated.

Feel free to make any comment about the procedure during your time here, or upon your return home. By this feedback we aim to make it a better treatment for all.

Information: Details regarding this treatment can be obtained by contact with one of the members of the team - (02) 9382 2539.