Surface Guided Radiotherapy
Surface Guided Radiation Therapy (SGRT) is a technique that significantly enhances the precision of radiation treatment across all types of cancers. It originated in 1979 with the use of cameras to map the body’s surface contours, gaining traction in radiotherapy by 2000 and becoming a pivotal tool in the field. Utilizing stereo vision technology, SGRT precisely monitors a patient’s surface, resulting in improved treatment outcomes, heightened patient safety, increased comfort, and accelerated treatment processes while minimizing errors.
SGRT relies on the patient’s external surface to ensure that radiation doses align precisely with the treatment plan. This involves the use of three camera units to monitor thousands of points on the patient’s skin, generating a real-time 3D surface image without the need for skin marks or tattoos. The system captures movements in six dimensions with submillimeter accuracy, enabling rapid interpretation and verification of the patient’s position throughout treatment. The radiation beam is activated only when the patient is correctly positioned, SGRT ensures optimal treatment quality and precision while minimizing the overall treatment time and imaging dose.
Recent clinical use of SGRT includes respiratory gating techniques. Since normal respiration can lead to organ motion, radiation therapy to tumors or lesions affected by respiration must be taken into consideration. Respiratory gating improves the quality and accuracy of radiation for lung and certain gastrointestinal cancers. SGRT with deep inspiration breath hold (DIBH) or shallow breath hold can overcome organ motion.
SGRT is widely used in patient positioning in patients with breast cancers. SGRT imaging provides guidance for correcting chin and arm position, thereby improving the breast position also. Left breast cancer irradiation using DIBH with optical surface scanners is nowadays widely implemented and this concept has also been adapted to right-sided breast irradiation for a reduction of lung and liver dose. SGRT enables protection to the heart from radiation therapy in left-sided breast cancer and significantly reduces damage to the radiosensitive structures of the heart such as the left anterior descending artery. DIBH also reduces the cardiac dose significantly in proton therapy for breast where any additional dose increases the risk of coronary artery disease and risk of ischemic heart disease. SGRT also helps in the setup of implantation of surgical clips for accelerated partial breast irradiation in early breast cancer.
SGRT benefits include treatment quality and comfort for brain and head and neck cancers. It also provides a way to perform Linac-based stereotactic radiosurgery for brain tumors providing better patient comfort and faster treatments. Prior to SGRT, patients had to have a frame fixed to their skull for achieving sub-mm accuracy especially in Gamma Knife machine. Patients with brain tumors using SGRT systems require the use of open-face masks or sometimes no masks. SGRT is appearing to be invaluable in cancers of the, prostate, abdomen, pelvis and cancers of the arms and legs.
Recently, a combination of SGRT with X-ray monitoring in a dedicated system has been introduced that enables a possibility of positioning the patient also according to the internal anatomy. Soon, SGRT systems could include entire clinical radiation therapy workflow, leveraging advancements in biometrics and face recognition algorithms. However, the reliability and accuracy of SGRT systems require robust Quality Assurance program to maintain submillimeter accuracy and safety in radiation
therapies. Continual evolution and integrated cutting-edge technologies hold promise in the field of radiation therapies offering hope and improved outcomes in patients battling cancer.