How the CyberKnife works
The vast array of different angles/trajectories from which pencil beams of radiation converge upon the tumour lead to an extremely high cumulative dose of radiation therapy at the convergence point (the target/tumour) and yet a very fast 'fall-off' of dose at the periphery of the carefully mapped target. The surrounding normal tissues/organs only receive a small fraction of the high central dose of therapy.
Whilst any tumour may be destroyed by a very high dose of radiation therapy, it has very often been the case, with orthodox radiotherapy, that it has not been possible to deposit the required dose on a tumour without also depositing a toxically high dose of radiation on the surrounding organs. CyberKnife® often overcomes this problem by its capability to so accurately target and achieve a fast dose gradient ('fall-off') at the perimeter of the tumour/target.
Brain tumour treatment
Arteriovenous malformations, other vascular anomalies (cavernoma, haemangioblastoma, glomus tumour), meningiomas, and acoustic neuromas are now (in many cases) preferentially treated by stereotactic radiosurgical techniques such as CyberKnife®. The success of radiosurgery has made orthodox surgery obsolete for many patients helps them to avoid the associated risks.
Spine cancer treatment
Many of the vascular problems that occur in the brain also occur in the spine and CyberKnife® has marked advantages over other radiosurgical techniques in that it is capable of targeting spinal lesions. Thus arteriovenous malformations of the spine are amenable to this radiosurgical technique and some other vascular anomalies that do not encompass too much of the normal spinal cord.
Other spinal cord tumours may be considered for CyberKnife® therapy and vertebral tumours may similarly be treated by this technology.
Lung cancer treatment
Single or several tumours in the lung may be obliterated by single or a few fractions of CyberKnife® radiation therapy. Highly focussed obliterative doses of therapy can be used to both kill/ablate individual lung cancers (primary or secondary) with sparing of the surrounding lung (more so than other radiotherapeutic techniques).
At the same session, the CyberKnife® can treat up to several lung tumours notwithstanding the fact that they may be sited in different lung areas.
Prostate cancer treatment
Since the introduction of PSA screening in men, the discovery of early prostate cancer has greatly increased in the Western world. Importantly, the disease is highly curable at this time, and there are a number of treatment options for such patients. The main three options available in recent years have been surgery, prostate radiation seed brachytherapy, and external beam radiotherapy/IMRT.