Radiosurgery has had a long history of success in achieving local control rates for metastatic disease in the brain. This treatment has recently been extended to other areas of the body and helps achieve local control for patients suffering from unresectable tumors of the liver and lung. The Cyberknife System is the only radiosurgery system in the world that can treat anywhere in the body to sub-millimeter accuracy. In addition, it uses a Monte Carlo dose calculation algorithm which is considered the gold standard of dosimetry. The Cyberknife System uses live patient motion tracking and a robotic X-ray unit to deliver doses much higher than traditional fractionated Radiation Therapy.
Volumetric Modulated Arc Therapy (VMAT)
VMAT is considered to be the most advanced delivery method for photon radiotherapy. VMAT delivers radiation by rotating the radiation machine around the patient; several arcs can be used, which allows our physicians to deliver highly conformal doses to both the identified tumor and regions of microscopic disease. The radiation fields continuously change shape to deliver the optimal dose to the tumor while sparing normal healthy tissue. VMAT takes less time to deliver than other techniques. At CCHS, we have been treating patients using VMAT since 2013.
Throughout the course of treatment, a patient’s anatomy may change due to any number of factors including: weight change, regression of local disease, and reduced tissue swelling following surgery. Tracking these changes requires sophisticated imaging algorithms. Deformable registration is the best way to precisely track radiation dose despite weight fluctuations or changes in internal organ geometry. In addition, we use this technology during the initial planning stages of treatment by adapting the CT and PET images taken during diagnosis. This eliminates excess radiation to healthy tissue from repeat scans.
Treatment planning is a complex problem and no two patients are the same. Using the RayStation planning system, we can generate dozens of treatment plans in a few minutes (rather than hours or days) that provide our physicians with the freedom to pick the best plan for each patient. This is called Multi-Criteria Optimization and is the cutting-edge of treatment planning that was recently introduced.