what is a cyber knife

what is a cyber knife

Cyber Knife is a robotic stereotactic radiosurgery system, designed in 1997 by American neurosurgeon John R. Adler, Professor of Neurosurgery and Radiotherapy at Stanford University and Peter and Russell Schonberg of Schonberg Research Corporation developed by Accuracy.

The idea of ​​the Cyber Knife is the engineering of the treatment, carried out in three dimensions designed by the physicist Renzo Carlo surplus with a traditional linear accelerator, a Varian 4 MV without any modification has been applied for the first time by the neurosurgeon Federico Colombo in November 1982 in the Department of Radiotherapy of the Hospital of Vicenza.

What technique inspired it?

This technique was in turn inspired by the equipment called the Gamma Knife, invented by the Swedish neurosurgeon Lars Leksell (1907 – 1986) and the radiobiologist Bjorn Larsson. The notable difference from Gammaknife is that the 3D linear accelerator system can be applied to any body district without being limited to intracranial targets. Other highly specialized neurosurgical centers have it, including in Europe.

First Installed

Today, about a hundred centers in Europe have this medical electrical equipment after the first one installed in Europe, in Vicenza, where the world’s first treatment in 3D with a standard linear accelerator had been conceived and implemented in November 1982, and now there were a series of thousands of treatments (in Italy, there are now 8 devices distributed between the North, Center and South).

Other highly specialized neurosurgical centers have it, including in Europe. Today, about a hundred centers in Europe have this medical electrical equipment after the first one installed in Europe, in Vicenza, where the world’s first treatment in 3D with a standard linear accelerator had been conceived and implemented in November 1982, and now there were a series of thousands of treatments (in Italy, there are now 8 devices distributed between the North, Center and South).

Other highly specialized neurosurgical centers have it, including in Europe. Today, about a hundred centers in Europe have this medical electrical equipment after the first one installed in Europe, in Vicenza, where the world’s first treatment in 3D with a standard linear accelerator had been conceived and implemented in November 1982, and now there were a series of thousands of treatments (in Italy, there are now 8 devices distributed between the North, Center and South).

Components of a Cyber knife

The Cyber ​​Knife is made up of certain components, including: robotic arm, linear accelerator, collimator, robotic bed, imaging system, and Synchronization system.

The robotic arm has 6 degrees of freedom and 120 main nodes (the points where the support robot can be placed) in which it can take up to 12 different directions for each of them, so I have a total of 1440 different orientations. with a positioning repeatability of less than 0.12mm. all this is very useful to have a more conformazioanlità possible for the treatment.

The linear accelerator is a compact system weighing 160 kg installed on the robotic arm. It uses 6 MV photons with a dose rate (Equivalent dose per unit time; Measured in Sv/h) of 800 MU/min. Inside there is a first form of collimation to which will be added the various secondary collimators that the cybernetic knife is equipped with. The secondary collimation system consists of 12 interchangeable circular collimators of various diameters (from 5 to 60 mm). In addition, there is also an IRIS collimator that has 12 moving segments to create fields of various sizes (same as circular collimators).

what is a cyber knife

The Cyber ​​Knife offers the possibility of selecting fixed collimators than IRIS thanks to a robotic system called Xchange, which automatically changes the collimator without having to interrupt treatment. The bed is the part of the machinery in which the patient is placed during the entire treatment. There are two versions of the latter: one with 6 degrees of freedom, the other with 5. This guarantees sub-millimetre precision in positioning, allowing the technician to make small corrections (during this phase) from the control station.

The imaging system is guaranteed by 2 pairs of low-energy X-ray sources on the ceiling and integrated amorphous silicon detectors on the floor. Regarding the pretreatment phase, two perpendicular images of the patient are acquired during positioning and subsequently recorded with the RRD (digital reconstructed radiographs) created by the TPS.

While for the intra-fraction image, before delivering the beam, the arm corrects the direction according to the patient’s position, real-time tracking of the lesion area through its surrogates. The robot can correct a maximum of: 10 mm for translations, 1° for El Paso and rotation and 3° for yaw. The Synchrony system is used to monitor respiratory movement and consists of 3 cameras mounted on a movable arm that can display LEDs placed on the patient. After that, this system is able to compare (thanks to external and internal markers) the external movement with that of the tumor; so we are able to follow the objective in each position it assumes throughout the treatment.

Uses of Cyber knife

The Cyber knife is an electromedical radiation therapy device used to eradicate forms of cancer. Therefore, its operation is based on irradiation (carried out with high power X-rays) of the patient from different angles to minimize damage to irradiated healthy tissues and obtain excellent focus on the target. Radiotherapy is made optimal by continuous monitoring of tumor location with a cross-system of stereoscopic X-rays and LEDs applied to the patient’s chest.

These chest LEDs allow you to follow the tumor during the patient’s breathing and automatically stop delivery in case of sudden movements. X-ray monitoring serves, instead, to locate the tumor, keep it monitored, correct breath-guided calibration and localize non-target tissues so therapy can be planned. The duration of the therapy, excluding the preparation time of the machine and the patient, lasts about ten minutes depending on the administration to be performed.

Treatments

However, consider that with this treatment a radiosurgical intervention is involved, that is, the use of relatively high doses to attack an extremely precise lesion. The therapies can be performed in a hypofractionated manner (dividing the beam into various fractions to minimize the dose absorbed by any organ at risk) or in a single session. There are several indications for surgical treatment with the Cyber ​​Knife. The treatments that prefer the use of this therapy are represented by benign and malignant tumors of the central nervous system, such as: of course, it is not only used for neuronal pathologies (as in the case of the Gamma knife), but also for lesions in areas critical, such as: spinal cord, liver, pancreas, lungs and prostate.

Tomotherapy

The same care is carried out by Tomotherapy, with the only differences that the administration is not carried out through an arm and a cradle is a robot, but with a gantry and a fixed bed (like other systems, then with a concentration of much lower dose than that obtained with 3D stereotactic irradiation as can be achieved with a Gamma knife or a Cyberknife that operate not in two but three dimensions (CT scans). In 2011 Accuray bought the Tomotherapy system for more than 277 million dollars.

Cyber knife has been on the market for several years. The evolution of this machine over the years has been based on increasing the software and optimizing it, in order to reduce the service time from a few hours to a few ten minutes. The cost of this machine is around 4 – 6 million € (VAT excluded). In addition, the Cyber Knife, like almost all radiotherapy devices, requires a bunker with technical specifications that guarantee an adequate level of safety for users and the health area.

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