NSW Government NSW Health
South Eastern Sydney Local Health District
nsw health

Stereotactic Radiosurgery (SRS)

What is Stereotactic Radiosurgery?

SRS involves the delivery of a high dose of radiotherapy to a very localised lesion (benign or malignant) within the brain or the skull base region around the brain. There are two recognised treatment methods of delivering this treatment.

  1. SRS
  2. SRS (IMRS) Intensity Modulated Radiosurgery

Due to the irregular shapes of some of the lesions Intensity Modulated Radiosurgery or IMRS technique can be implemented. This technique enables the specialist to shape the beam to better treat the lesion and minimise the dose to normal tissue. This approach may also be applied to tumours outside the brain.

Types of tumours suitable for Stereotactic Radiosurgery include:

Benign tumours:

Malignant tumours:

  • Arteriovenous Malformations
  • Meningiomas
  • Pituitary tumours
  • Vestibular Schwannomas/Acoustic Neuromas
  • Trigeminal Neuralgia
  • Cerebral metastases
  • Consultation for SRS with the Specialist:

    Not all patients are suitable for SRS. Lesions that are too large or close (within 3mm) to the optic chiasm, (the nerve responsible for vision) determines that the radiotherapy given stereotactically has to be in small doses each day over a number of fractions with doses ranging from 30 -70Gy.  This is referred to as Stereotactic Radiotherapy.

    Scans are evaluated at the time of consultation and discussion regarding the benefits and possible side effects of the procedure will also be discussed. Stereotactic Radiosurgery works in the same way as other types of radiotherapy, however the aim of the treatment is not to obliterate the tumour rather 'halt' the tumour cells from multiplying resulting in 'Lack of Progression' or stabilising the tumour. This is with the exception of Arteriovenous Malformations for which the treatment aim is complete obliteration of the lesion.

    There are currently a number of research studies being done at The Prince of Wales Cancer Centre on Stereotactic Radiosurgery, one example is the Meningioma study (a benign lesion) where the Lack of Progression Rate to date is 95%.

    At consultation a Stereotactic Radiosurgery Brochure will be given to you outlining details of the treatment and the procedure for the day.

    If the decision is made to treat, you will be contacted confirming the day, date and time. The Research Manager will also contact you 1-2 days prior to treatment to discuss your treatment, medications (eg., if you are diabetic), parking, pacemaker, clips etc, allergies, claustrophobia and any special needs you may have.

    Day of Procedure:

    Your clinician would have taken a detailed medical history noting medications and allergies. Please inform the Study Co-ordinator if you are diabetic.
    The staff at the Radiation Oncology reception desk will be expecting you on your day of treatment, please advise the staff when you arrive. Also bring previous scans, Medicare card and any current medication (insulin if diabetic) you take during the day.

    Stereotactic Radiosurgery involves eight phases:

    1. MP-Rage

    2. Administration of analgesia (codeine forte) and anti-nausea medication (if required) approximately 15 minutes prior to headring application

    3. Administration of local anaesthetics x 2 to numb the scalp area
    4. Application of headring
    5. CT fusion
    6. Computerised planning
    7. Radiation treatment (this component of your treatment may range from half an hour to two hours)
    8. Post procedure/treatment discussion with clinician regarding acute post SRS side-effects and follow up appointments.

    Pre-Treatment Imaging:

    Patients are escorted to Radiology for an MP-Rage (or mini MRI) which takes approximately 7-10 minutes using intravenous contrast and is for planning purpose only.

    Mid-Morning: - Headring Fitting
    Your treatment relies upon developing co-ordinates used to define exactly where your lesion and adjacent brain structures are. This is done by using a metal ring reference plane around your head.

    Prior to the headring fitting, local anaesthetics x 2 are given in 2 stages:

    1. injections x 4 of fast acting local anaesthetics (numbs the area within seconds)
    2. injections x 4 of long-lasting local anaesthetics (should last for approximately 6-8 hours) to alleviate pain

    The headring is then attached which should take no more than 10 minutes.

    CT Fusion
    A CT scan is done taking approximately half an hour without contrast dye. If you have an AVM lesion an Angiogram is also required.

    Radiation Treatment
    Radiation treatment involves two radiation therapists and a stereotactic registered nurse. Treatment usually ranges from half an hour to two hours depending on the complexity of the procedure and is done late afternoon. Treatment is divided into segments and you lie on the patient couch being moved to a different position for each segment.

    Post Procedure
    The clinician will remove the headring. An oral steroid (dexamethasone) and anti-nausea tablets are administered to help reduce any intracranial swelling and possible headache. When you are comfortable you will be discharged.  Your clinician will discuss periodical follow up appointments and MRI monitoring. The Research Manager will keep in regular contact with you to check your post stereotactic progress.