31 Aug Cyberknife

Another tool that is used in radiation therapy is a machine called Cyberknife. Cyberknife is a newer technology that allows a robot to treat a patient with a high dose of radiation to the cancer area. This is what the Cyberknife looks like:

It also has a small accelerator structure inside the top of the machine. It is placed on a robotic arm that can move very quickly in any direction. This robot is the same kind of robot that is used for welding in the Auto industry.
It help us to treat cancer patients in a couple of really cool ways. Since the radiation can be “pulsed” or turned on and off very quickly, it allows us to create very small pencil like beams of radiation and then concentrate them in a particular area over the tumor. Since the machine can move all around the patient. we can create several hundred different beams and then focus them all at one point inside of the patient, directly at the tumor site. This allows us to increase the dose to the cancer, and really decrease exposure to normal tissues. This helps with better chances for a cure, and less side effects. Here is a picture of how many different beams converge on a tumor near the spine:

In order for the machine to know where the tumor is located inside of the patient, fiducial markers have to be placed inside of the patient as well. Typically these fiducials are about the size of a grain of rice, placed either under the skin or directly into a tissue or organ. They are either made from Gold or n opaque substance that can be seen on a film. Once they are placed inside of the patient, a CT is obtained and then there locations are placed into a computer. Once the physicians locates the fiducials, the tumor, and any critical structures it is then sent to the Cyberknife. By using this information, it then uses 6 cameras to detect where the location of the fiducials, and then can distribute radiation from various angles in order to deliver the correct amount of dose to the cancer. It is kind of like a GPS system for cancer.
Cyberknife is wonderful for tumors that are located inside of the brain. Historically patients would have to have a large halo placed on their heads, drilled in place into their skull, and then that frame was attached to a couch during treatment. This would physically lock the patient in place and they would not be able to move at all during treatment. This frame was also very heavy. With Cyberknife there is no need for a frame system. Since fiducials can be placed just under the skin in the skull, it can allow the machine to track where the patient and the tumor are at any time and point in space. This is better for the patient, and it also means that they do not have to wear this large halo anymore.
Another cool feature of Cyberknife is that if you placed fiducial markers inside of a lung cancer, you can then track the motion of a lung cancer. When we breath are chest move. If you can imagine a cancer inside the lung, every time you breath, it moves. Cyberknife allows us to track that moving and reduce the area that we would typically have to treat with radiation. Since lungs are very sensitive to radiation, damage can occur very easily to the normal tissues. This is just another advantage that we have for treating lung cancer. It allows us to see that motion, account for it, target the lung cancer precisely, and then limit the exposure to the normal tissues.
If you have any further questions, please feel free to email me: CANCERGEEK@GMAIL.COM
-CancerGeek