The challenge that doctors face with tumors in the lung is that those tumors move as the patient breathes. The CyberKnife offers patients a new option for the treatment of lung cancer. Unlike traditional radiation therapy, the CyberKnife precisely identifies the tumor location as the patient breathes normally during treatment and can be used, in some cases, to treat lung tumors non-invasively.
The CyberKnife treatment generally involves four steps:
As part of the diagnosis, doctors will identify the location and size of the lung tumor. Depending on these results, some patients may not require the implantation of fiducial markers. The CyberKnife will use only the identifying characteristics of the tumor itself to clearly visualize the tumor within the chest and track the tumor as the patient breathes normally.
Some tumors may require the placement of fiducials within the lung to help the CyberKnife pinpoint the tumor’s exact location. In that case, the patient will be scheduled for a short outpatient procedure beforehand in which three to five tiny gold seeds -- called fiducial markers -- are inserted into the tumor or surrounding lung tissue. These markers may be placed by putting a small needle through the chest, guided by CT scan or an ultrasound. Alternatively, a camera might be passed through the patient’s mouth and into the airways or into the esophagus to allow access to the tumor. If fiducials are required, the patient must wait approximately one week before CyberKnife treatment planning can begin to ensure that fiducial movement has stabilized.
Before CyberKnife treatments can begin, patients will be fitted for a special body cradle. The cradle is made of a soft material that molds to the patient’s body and is designed to make treatment more comfortable and to ensure body position is the same for each treatment session. The patient also will be fitted with a special vest, which is worn during CyberKnife treatment and enables the robot to correlate chest motion and breathing patterns with the tumor position. The data generated with the vest allows the CyberKnife robot to precisely follow the tumor’s motion as it delivers each beam of radiation, ensuring safe and accurate radiation delivery.
While lying in the cradle, a CT scan will be performed to locate the patient’s tumor. This CT data will be used by the CyberKnife team to determine the exact size, shape and location of the tumor. A MRI or PET scan also may be necessary to fully visualize the tumor and nearby anatomy. Once the imaging is done, the patient will remove his or her vest and it will be stored with the custom-fit body cradle for use in CyberKnife treatment.
A treatment plan will be specifically designed by a medical physicist in conjunction with the patient’s doctors. Patients will not need to be present at this time. During treatment planning, the CT, MRI and/or PET scan data will be downloaded into the CyberKnife’s treatment planning software. The medical team will determine the size of the area to be targeted by radiation and the radiation dose, as well as identifying critical structures – such as the spinal cord or vital organs – where radiation should be minimized.
At this time, the CyberKnife will be able to calculate the optimal radiation delivery plan to treat the lung tumor(s). Each patient’s unique treatment plan will take full advantage of the CyberKnife’s extreme maneuverability, allowing for a safe and accurate lung cancer treatment. After the treatment plan is developed, the patient will return to the CyberKnife Center for treatment. The treatment is usually delivered in one to five sessions.
For most patients, the CyberKnife treatment is a completely pain-free experience. They may dress comfortably in street clothes and the CyberKnife center may allow the patient to bring music to listen to during the treatment. The patient also may want to bring something to read or listen to during any waiting time, and be accompanied by a friend or family member to provide support before and after treatment.
When it is time for treatment, the patient will be asked to put on their vest and lie on their custom body cradle. The radiation therapist will ensure the vest is properly adjusted and that the patient is positioned correctly on the treatment couch.
As treatment begins, the location of the lung tumor will be tracked and detected continually as the patient breathes normally. The medical team will be watching every step of the way as the CyberKnife tracks the patient’s lung tumor as it moves, and safely and precisely delivers radiation to it.
The CyberKnife’s computer-controlled robot will move around the patient’s body to various locations from which it will deliver radiation. At each position, the robot will stop. Then, special software will determine precisely where the radiation should be delivered by correlating breathing motion with the tumor. Nothing will be required of the patient during treatment, except to relax and lie as still as possible.
For more information about CyberKnife, call 253-403-6399.