Gamma Knife® FAQs

Contents

• What is Gamma Knife®?
• What is special about Gamma Knife®?
• What can Gamma Knife® treat?
• What does a typical Gamma Knife® treatment consist of?

What is Gamma Knife®?

The Gamma Knife® is a machine designed to deliver radiation in a very precise manner by targeting hundreds of pinpointed beams of radiation directly at the tumour. This is a non-invasive and non-surgical treatment for brain conditions.

What is special about Gamma Knife®?

Gamma Knife® is an innovative treatment and, despite the name, does not involve surgery or knives. Although it is state-of-the-art technology it has stood the test of time since the late 1960s when the prototype was first used. Gamma Knife® allows the traditional beam radiation, which is delivered to patients with tumours, to be administered as a day case procedure. This is in contrast to conventional radiotherapy which involves radiation being administered in small doses over weeks.

What can Gamma Knife® treat?

Gamma Knife® can be used to treat the following conditions in the head and neck (please click on the links for more information). For radiosurgery below the neck alternatives include CyberKnife® or TrueBeam.

• Acoustic neuroma (vestibular schwannoma)
• Arterio-venous malformations (AVMs)
• Cerebral metastases
• Brain tumours
• Meningiomas
• Metastatic Deposits
• Pituitary Tumours
• Trigeminal Neuralgia
• Other skull base tumours

Please note that Gamma Knife® would not normally be used to treat tumours greater than 3.5cm in diameter or large vascular malformations. Primary brain tumours such as astrocytomas and glioblastoma multiforme are generally not suitable for primary treatment with radiosurgery but Gamma Knife® is sometimes used as a boost therapy after conventional treatment has been given.

What does a typical Gamma Knife® treatment consist of?

• The day starts at 07:30 at St Barts Hospital, London in the MRI department. A consent form will be signed by the patient to allow us to proceed with the radiosurgery.
• Local anaesthetic will be injected into the scalp to allow fixation of an aluminium frame to the skull using 4 titanium tipped screws. This provides a fixed reference to allow the computer software to determine the location of the target within the head with an accuracy of around 1mm.
• An MRI scan is then taken with the frame in position to provide the dataset needed for the software dose planning
• The patient is then taken to the Gamma Knife Centre and waits for the dose planning to be completed and checked before the treatment is given
• The required total dose of radiation needed to treat the problem is selected and the treatment plan ‘signed off’. The Gamma Knife® surgery is given, in a treatment time determined by the size of the target and the total dose of radiation needed. Usually this involves less than one hour of treatment after which the frame is removed.
• The patient is normally discharged within an hour of the end of treatment but some will be advised to stay in hospital overnight.

Following the treatment a follow-up is usually carried out by the referring doctor, who may be one of the treating clinicians. This usually involves a brief check after six weeks to ensure that there have been no undue side effects and then normally involves MRI scans at intervals to check on the results of treatment.