More effective treatment with new technology
CyberKnife is a precision radiation therapy device based on robotic technology. The system can be used for cancer treatments and also for bening tumours and other medical conditions.
The photon radiation delivered with the CyberKnife system is produced in a small linear accelerator positioned at the hand of the robot. X-band linear accelerator can produce 6 MV photon radiation at high dose rate. Similar radiation can be produced with conventional treatment machines, but the way the CyberKnife can deliver and aim the radiation beams to the patient is unique. Because of highly agile and accurate robot, the radiation beams can be directed to the target from different angles avoiding sensitive organs and sparing normal tissue.
Robotic assisted technology
The robot is German made KuKa kr-240, which is commonly used also in car industry. This model is however extensively modified to work as a medical device for radiotherapy. The robot is highly accurate, with capable of hitting a moving target at 0,5 mm accuracy. The high accuracy together with multiple beam delivery directions enable to treat confidently small targets at difficult positions.
CyberKnife will locate its target by comparing patient’s 2D images from the treatment planning system to the images taken from patient before and during the treatment. These treatment images are taken with an integrated X-ray imaging system. The system consists of two X-ray sources at the ceiling and two large digital image detectors embedded at floor. CyberKnife system utilizes live image guidance and if the patient or the target moves during the treatment session, this will be detected and corrected by changing the directions of the robot, or moving the robotic couch on where patient lies.
Traditionally radiotherapy patients are fixed in a reproducible and immobile position during the treatment. This is usually realized with several different fixation devices which limit and prevent patient from moving. With the CyberKnife system the image guided target tracking enables fixations that are easy to use and much more comfortable for the patients. When the patient and the target position is monitored during the treatment, rigid immobilization is no longer needed in most cases.
When delivering radiation therapy to a target which moves along with a breathing cycle, the synchrony tracking is being used. This system enables the robot to move with the target and irradiating it during the breathing pattern in real time. It could be said, that the robot is breathing with the patient and following the breathing pattern. This synchrony system calculates an individual breathing model by utilizing three cameras and LED lights fastened in a synchrony vest, which the patient wears during the treatment. With the cameras tracking the movement of the chest wall and simultaneously the X-ray imaging system tracking the target, CyberKnife's computer system is able to calculate a predictive model of the patient’s breathing cycle. The model is used to predict in 10ms beforehand where the target will be in every phase of the breathing cycle. The model is constantly updated during the treatment, so if the breathing pattern changes, it will be observed and taken in to account. If there is unpredicted movement, such as cough or yawn, the treatment will stop immediately. After the possible abrupt action, the model is being verified and the treatment is continued after the verification. This synchrony system is easier for the patients because they can breathe normally during the treatment, unlike with other respiratory systems available, where the patients have to hold their breath or breathing is actively controlled via breathing device during the treatment.
Delivering CyberKnife radiotherapy
CyberKnife radiotherapy treatments are delivered with hundreds of small photon beams (diameter ranging from 5-60mm). The radiation beam diameter is changed with a collimator. The robot can change the size of the collimator very fast with an Iris(tm) collimator, which works as cameras iris, reducing and increasing the opening. With some treatments, only few beam sizes are needed, so Iris(tm) is not needed. Robot can then pick up a suitable fixed collimator from an exchange(tm) table next to the robot. This is done automatically even during the treatment.
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