HJAR Nov/Dec 2021

HEALTHCARE JOURNAL OF ARKANSAS I  NOV / DEC 2021 43 Scott Yakoubian Director of Medical Physics, Dosimetry and RSO CARTI, Inc. to the treatment and models the patient’s re- spiratory pattern, accurately predicting the lesion’s location. During treatment, real-time X-ray images allow the system to monitor a lesion’s actual location and adjust the re- spiratory model using artificial intelligence. The system uses the updated location infor- mation to make minute adjustments to the robot, thus compensating for lesion motion and precisely delivering the prescribed dose to the intended area. The “Accuray Precision” treatment plan- ning system that designs a patient’s treat- ment uses the most accurate calculation engine available: Monte Carlo. Aided byAc- curay Precision, the radiation oncologist can accurately develop the optimal treatment plan accounting for each patient’s unique anatomy. Each treatment plan is custom- ized for each patient, taking advantage of CyberKnife’s one-of-a-kind technology. With these technologies, CyberKnife is ideally suited to treat a host of central nervous system (CNS) diseases with ste- reotactic radiosurgery (SRS) and fraction- ated stereotactic radiation therapy (FSRT). The thousands of unique treatment beam angles allow for the treatment of simple and complex brain metastases, skull base lesions, as well as certain functional disor- ders like trigeminal neuralgia, while sparing normal brain tissue. Similarly, aggressive treatment of spine lesions can be performed safely while sparing the adjacent spinal cord by tracking spine position in real time and adjusting the treatment beam appropriately. Using real-time tumor and fiducial track- ing, CyberKnife also allows for highly ef- fective and safe treatment with stereotactic body radiotherapy (SBRT) to a number of tumor sites throughout the body. For some sites like lung cancer, CyberKnife is able to track lung tumors during the respiratory cycle and continually adapt the treatment beam to target the tumor as it moves dur- ing normal breathing. This results in smaller required margins and less dose to a multi- tude of nearby critical structures, such as normal lung, heart, blood vessels and spine. For other tumor sites, such as the prostate, liver and pancreas, CyberKnife is able to detect and track implanted fiducial metal markers and automatically adapt the treat- ment accordingly. For liver and pancreatic tumors, motion is largely due to respiratory motion, while for prostate cancer, it is largely due to bowel and bladder filling.Additionally, despite traditionally used devices to limit patient motion during treatment, inevita- bly, there is always some small amount of patient movement during treatment. This al- lows another layer of quality assurance that this motion is accounted for and that it will not cause inadvertent treatment of normal structures or missing of the target altogether. The concept of stereotactic treatments (SBRT, SRS and FSRT) is not new, but they have attracted more attention recently. Tra- ditional treatments for lung cancer could be as long as six to seven weeks, but for some early-stage lung cancer, treatment with SBRT can be performed in as few as three to five treatments over approximately a week and a half. Not only is the treatment course short- er, but these treatments are also tolerated very well with patients, typically experienc- ing minimal side effects and having success rates greater than 90%. Similarly, traditional radiation treatment courses for prostate can- cer are among the longest of any treated tu- mor site, sometimes approaching nine weeks and 45 treatments. While we have been able tomoderately shorten this for most patients — so-calledmoderate hypofractionation that is four to five weeks of 20 to 28 treatments — some patients are able to be treated with prostate SBRT in as few as four to five treat- ments with excellent biochemical control and few side effects. The publication of multiple clinical trials demonstrating survival benefits with the addition of SBRT to the standard-of-care chemotherapy in patients with oligometa- static disease (limited number of metastatic sites of disease) has shifted the way we ap- proach these patients. Instead of a one-size- fits-all approach to metastatic disease, we know that these patients will live longer on average. Additionally, data shows that ag- gressive local treatment to sites of disease in addition to systemic treatment improves it even more. In addition, in patients with more widespread metastatic disease, the proliferation of targeted chemotherapy and immunotherapy options means patients are living longer, making the need for durable local control with treatments such as SRS and SBRT more important, as well. These types of treatments result in life- changing benefits for patients. Fewer treat- ments mean fewer visits and more time at home with family. Additionally, real-time tumor tracking and robotic precision deliv- ery mean fewer side effects and potentially higher control rates. n Matthew E. Hardee, MD, PhD, is board certified by the American Board of Radiology. He completed a residency in radiation oncology at New York Univer- sity School of Medicine in New York, New York, and earned amedical degree fromDukeUniversity School of Medicine in Durham, North Carolina. ScottYakoubian,Director of Medical Physics,Dosim- etry and RSO, leads the department that covers all of CARTI’s treatment locations that offer radiation oncology.Yakoubian serves on the State ofArkansas’ Ionizing Radiation Licensure Committee and serves on an American Association of Medical Physicists Leadership subcommittee. He received a degree from Georgia Institute of Technology and has been in the field for 27 years.