Gamma knife Vs. Cyberknife: radiosurgery to treat cancer and other diseases
Written in association with:Radiosurgery is not a conventional surgery for radiation therapy as it does not involve cutting with a knife, even though it uses the processes referred to as Gamma Knife and CyberKnife surgery. It is not undertaken in an operating theatre and patients are usually awake as its not painful, no anaesthetic is needed and they often go home on the same day.
What is stereotactic radiosurgery (CyberKnife and Gamma Knife)?
Stereotactic radiosurgery is a form of radiation therapy, which focuses high-power energy on a small area of the body without making incisions and minimises damage to nearby healthy cell tissues. ‘Radio’ refers to radiation usually in the gamma band. This type of radiation can penetrate human tissue and kill malignant cells that have clumped to form a tumour or lump. ‘Stereo’ refers to the ability to focus this radiation in all three dimensions onto a point in the body.
Why is stereotactic radiosurgery performed?
This type of treatment is very accurate, often achieving sub-millimetre precision. It is very useful in treating tumours in the brain or spinal column, which can lie next to very important structures such as the optic nerve or spinal cord that are delicate and need protecting.
How is stereotactic radiosurgery performed?
There are two ways in general to deliver stereotactic radiation:
1. Gamma Knife Surgery: using a fixed source of radiation, which is almost exclusively used for tumours in the brain. Often the head is fixed firmly in a frame when delivering such invasive treatment.
2. CyberKnife Surgery: it can be delivered using a beam of radiation fixed to a robotic arm so that the beam can be delivered in several pathways. This is a newer evolution and is non invasive.
How should a patient prepare for stereotactic radiosurgery?
Patients usually do not need to make special preparations but the specialist doctors and team delivering the treatment use sophisticated computers to work out doses and plan trajectories. It helps the patient to have done some reading to know what to expect, and to ask their doctor questions.
Are there any risks?
Despite stereotactic radiosurgery being very safe there are small risks. These can be divided into:
- Early risks – these may arise from damage to structures, which lie very close or even touch the target tumour. Some of the radiation may fall into these structures.
- Late risks – a problem may be the risk of inducing cancer of a different kind because of the radiation. This risk is very small but it does rise according to the size of the tumour and amount of radiation given.
What is the long-term outlook?
This depends on the type of tumour and if it has already spread to several locations. Often if a tumour is large, or if wrapping around a vital structure, then a doctor may feel this type of treatment is too risky or inappropriate. Whilst this is an amazing type of treatment, there are limitations. Often several teams of doctors and other specialist care workers such as radiographers, physicists and specialist nurses are involved in treating any one patient.
