Western Australia will soon be equipped with one of the latest worldwide technologies for cancer treatments. The CyberKnife is a multi-million dollar system which is being installed in the department of Radiation Oncology at Sir Charles Gairdner Hospital in Perth.
The CyberKnife (Accuray Inc., Sunnyvale, CA) is a non-invasive alternative to surgery for the treatment of both cancerous and non-cancerous tumours anywhere in the body, including the prostate, lung, brain, spine, liver, pancreas and kidney. Although suitable for multiple sites the CyberKnife will provide a distinct advantage over and above more conventional radiotherapy in particular circumstances, such as when radiation damage to nearby healthy anatomy cannot be avoided with more conventional approaches. The treatment – which delivers beams of high dose radiation to tumours with extreme accuracy – offers new hope to our patients.
The CyberKnife has an intelligent robotic design and can move around the patient. It is non-invasive treatment for patients with surgically complex or inoperable tumours. The system targets the tumour anywhere in the body with sub-millimetre accuracy. Precise tumour targeting is even more important for treatment of the tumours with some level of respiratory-induced movement.
The CyberKnife is an image-guided system to chase and target the tumour. It consists of an orthogonal pair of X-ray cameras coupled to a small X-band linear accelerator mounted on a robotic arm which allows the beam to be directed at any part of the body from any direction. Using a higher microwave frequency in the X-band for accelerating electrons reduces the size and weight of the accelerator substantially. As a result, the CyberKnife linear accelerator is small, lightweight (~120 kg), and yet generates a 6-MV X-ray beam.
The imaging system in CyberKnife consists of two diagnostic X-ray tubes mounted orthogonally (90 degrees offset) in the ceiling and two opposing flat-panel detectors. The system is capable of acquiring and processing multiple images for patient setup as well as for tracking the target (tumour) motion during treatment. The target location is confirmed relative to skeletal structure by comparing real-time radiographic images with the reference treatment planning CT images. The robotic arm has six degrees of freedom and is capable of manoeuvring and pointing the linac beam almost anywhere in space. After sensing any target motion, the robotic arm moves the beam to the newly detected target position for alignment.
In addition to vast benefits to the patient, the availability of this modern device provides a great opportunity for researchers to explore and investigate more in the field of Medical Physics, and improve the performance and efficiency of the existing system.