Some time before the day of treatment the patient meets with their consultant to discuss the details. The treatment process, along with its advantages, disadvantages and risks will be explained, and the patient will have the opportunity to ask questions – a process which is encouraged.
It will be necessary to move between hospital sites, as there are no imaging facilities at The London Gamma Knife Centre. An ambulance team and the gamma knife nurse will facilitate transport on the day of treatment for the patient only. We regret that we cannot assist with any additional transport.
On the day of treatment the patient is met by their treating consultant, who will explain the process again, and the patient is asked to sign a consent form. A neurosurgical nurse remains with the patient for the entire day of treatment.
The day can be broken down into 6 different events:
A stereotactic frame is attached to the patient’s head. This frame enables the team to locate and target the lesion and is held in place by four surgical pins - two on the forehead, and two at the back of the head. These pins pierce the skin and are tightened so that they rest on the outer bone of the skull. A long acting local anaesthetic is injected at each site so no pain should be experienced, although patients do feel tightness, pressure and some discomfort as the pins are tightened. This feeling of discomfort usually resolves itself after about 15 minutes but some patients do continue to experience a degree of headache. The frame is worn for the entire day and is only removed after the gamma knife treatment has been completed.
All patients require an MRI scan for the purpose of treatment planning. Patients being treated for an AVM will also require an angiogram. These examinations are performed while the frame is being worn and their purpose is to enable accurate targeting and planning of treatment. CT scanning can be used for those patients who are unable to undergo MRI scans for medical or other reasons.
Gamma knife treatment is then planned by the consultant and the physicist, using the images which have been digitally imported into specialised software. In some cases this
can be a lengthy process, taking up to two hours. During this time the patient stays in the waiting room (an accompanying person is welcome) and is free to eat and drink and interact socially.
The patient is positioned in the gamma knife unit and secured in place using the frame. The treatment is divided into a number of fractions or ‘shots’, the patient being re-positioned after each shot of treatment. The number of shots required to make up a treatment varies greatly and depends on the size, site, and shape of the lesion. The treatment for trigeminal neuralgia is atypical; it consists of a single shot lasting 30-60 minutes. Treatment delivery can take from about 30 minutes up to about four hours, depending on the number of shots and the complexity of the treatment plan.
The frame is removed immediately after completion of treatment. This is quicker than the fitting of the frame and does not usually cause any distress. The tiny pin sites are dressed with a bandage. The patient is then transported back to the hospital for an overnight stay.
Patients are usually required to stay overnight for observation and are discharged the following morning with the clinician’s consent. For some patients, especially if the radiation dose given has been minimal and not in a critical area, the patient can go home shortly after treatment. A follow-up appointment will be arranged and a letter confirming this will be sent a few weeks after treatment.