Radiosurgery, the therapy of brain tumors, has long been made using a so called Gamma Knife with high activity sealed sources such as Cobalt-60. Nowadays the therapy can also be made with a linear accelerator such as a Cyber Knife. What are your experiences? Can you share advantages and disadvantages of each system. At the end do you think that the use of radioactive sources is still (medically)justified for radiosurgery given the alternative of a Linear accelerator?
Dear Dr. Flury,
both Gamma Knife (GK) and CyberKnife (CK) have unique specifications for the application of radiosurgery but deviding them in pros and cons is really subjective. For example, using a rigid head fixation in an MRI examination immediately before treatment planning and application (GK) is the nearly ideal situation for a radiation therapist. This is the main advantage of GK in my opinion as it is highly specialized system for very small intracranial lesions. But, frameless immobilization (CK) is less invasive and more convenient for the patient and can result in similar targeting precision and accuracy when combined with X-ray based alignment and use of previous MRI data (rigid and deformable image registration available). Moreover, CK can also be used for extracranial targets including tracking option for motion compensation (needs x-rays) and also with larger field sizes (different collimator options avialable). This high flexibilty is the main advantage of CK in my opinion. Of course, one can find other pros and cons depending on which specification you look at regarding patient workflow:
http://pasadenacyberknife.com/cyberknife-vs-gamma-knife/
https://www.valleygammaknife.com/gamma-knife-vs-cyberknife/
There are also comparisons on dose distribution with advantages and disadvantages for both systems, e.g.
Article Comparing Gamma Knife and CyberKnife in patients with brain metastases
From radiation protection point of view, shielding of Co-60 radiation (GK) is easier compared to 6 MV Linac photons (CK). But, Co-60 sources needs to be regularily exchanged causing radioactive waste and also theft proctection is an issue, which could the main disadvantage for public authorities.
Best regards
Radiosurgery is applicable to patients with primary brain/head tumours with brain metastases, vascular malformations and a number of functional diseases. Gamma Knife can only targert different types of cancer with a single treatment session of high-dose radiation, while CyberKnife is able to treat cancer anywhere on the body in one to five radiation treatments. The recovery period of Gamma Knife radiosurgery is minimally invasive with a short and mild recovery period.
The gamma knife is used for pathologies of the head with a diameter of less than 3 centimetres. The LINAC is a radiation device which emits X-rays. LINAC has tertiary collimators (multileaf or ring collimators) which allow the radiation therapist to direct the radiation focus as precise as is necessary to treat the lesions. In the gamma knife, the adapted linear accelerator has only one source of rays. This emitter head must therefore be moved around the patient, otherwise (with a single entrance point) the tolerance of the tissue in the pathway of the ray would be exceeded quickly and –as a consequence- the therapeutic target dose in the target lesion could not be reached. Moving parts the complex feature of the moving parts of the LINAC system require a vast amount of maintenance and quality control rather than Co-60 gamma knife.
both of thes are very accurate, the important factor is how you use these tools. how well can you define the target and can you plan it with minimum dose to the normal tissues
Regarding the quality of up-to-day medical linear accelerators it is kind of marketing to sell special devices for stereotactic radiosurgery.
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