The challenge that physicians face in treating lung tumors is that the tumors move as the patient breathes. *
Radiosurgery devices, such as the CyberKnife® Robotic Radiosurgery System, offer patients a new option for the treatment of lung cancer. Unlike traditional radiation therapy, the CyberKnife System precisely identifies the tumor location as the patient breathes normally during treatment, and can be used, in some cases, to treat lung tumors noninvasively.
Before a typical CyberKnife treatment
Lung cancer treatment with the CyberKnife System involves a team approach in which several specialists participate. The patient’s team may include:
- Radiation oncologist
- Interventional radiologist
- Medical physicist
- Radiation therapist
- Medical support staff
Once the team is in place, preparations begin for CyberKnife treatment.
As part of the diagnosis process, physicians will have identified the location and size of the lung tumor. Depending on these results, some patients may not require the implantation of tiny fiducial markers (used as reference points to aid in tumor location). The CyberKnife System will use only the identifying characteristics of the tumor itself to clearly visualize the tumor within the chest and track it as the patient breathes normally.
Some tumors may require the placement of fiducials within the lung to help the CyberKnife System pinpoint the tumor’s exact location. In that case, the patient is scheduled for a short outpatient procedure beforehand in which three to five tiny gold “seeds” – fiducial markers – are inserted into the tumor or surrounding lung tissue. These markers may be placed by putting a small needle through the chest wall, 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 begin, a special custom-fit body cradle is made. 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 is also fitted with a special vest, which is worn during treatment. The data generated using the vest allows the CyberKnife robot to correlate chest motion and breathing patterns with the tumor position, precisely following the tumor’s motion to deliver each beam of radiation. This ensures safe and accurate radiation delivery.
With the patient lying in the cradle, a CT scan is performed to locate the patient’s tumor. This CT data is used by the CyberKnife team to determine the exact size, shape and location of the tumor. An MRI or PET scan also may be necessary to fully visualize the tumor and nearby anatomy. Once the imaging is completed, the patient removes his or her vest and it is stored with the custom-fit body cradle for use in CyberKnife treatment.
A treatment plan is specifically designed by a medical physicist in conjunction with the patient’s physicians. The patient need not be present. During treatment planning, the CT, MRI and/or PET scan data is downloaded into the CyberKnife System’s treatment planning software. The medical team determines the size of the area to be targeted by radiation and the radiation dose, and identifies critical structures – such as the spinal cord or vital organs – where radiation should be minimized.
At this time, the CyberKnife System calculates the optimal radiation delivery plan to treat the lung tumor(s). Each patient’s unique treatment plan takes full advantage of the CyberKnife System’s extreme maneuverability, allowing for a safe and accurate lung cancer treatment. After the treatment plan is developed, the patient returns to the CyberKnife center for treatment, which is usually delivered in one to five sessions.
The treatment session
For most patients, the CyberKnife treatment is a completely pain-free experience. They may dress comfortably in street clothes, and are free to bring music to listen to during the treatment. Patients also may want to bring something to read or listen to during any waiting time, and have a friend or family member accompany them to provide support before and after treatment.
At treatment time, the patient puts on his or her vest and lies on the custom body cradle. The radiation therapist ensures that the vest is properly adjusted and that the patient is positioned appropriately on the treatment couch.
As treatment begins, the location of the lung tumor is tracked and detected continously as the patient breathes normally. The medical team monitors every step via closed-circuit TV as the CyberKnife tracks the patient’s lung tumor, and safely and precisely delivers radiation to it.
The CyberKnife System’s computer-controlled robot moves around the patient’s body to various locations from which it delivers radiation. At each position, the robot stops and special software determines precisely where the radiation should be delivered by correlating breathing motion with the tumor’s location. Nothing is required of the patient during treatment, except to relax and lie as still as possible.
Once treatment is complete, most patients quickly return to their daily routines with little interruption of their normal activities. If treatment is being delivered in stages, the patient will need to return for additional treatments over the next several days as determined by his or her physicians. Most patients experience minimal side effects, which typically go away within the first week or two after treatment. Physicians will discuss all possible side effects with their patients prior to treatment. In addition, they may prescribe medication to control any side effects, should they occur.
After completing a CyberKnife radiosurgery treatment, it is important for patients to schedule and attend any follow-up appointments. Each patient should be aware that his or her tumor will not suddenly disappear. Response to lung cancer treatment varies from patient to patient. Clinical experience thus far has shown most patients respond very well to CyberKnife treatments. Physicians will monitor the outcome in the months and years following a patient’s treatment, often using CT scans or PET-CT scans.
*Source material drawn from www.cyberknife.com Please refer to that website for a complete listing of references used in the original information sections.
CyberKnife® is a registered trademark of Accuray Incorporated.