Stereotactic body radiotherapy

Application of high dose radiotherapy in single fraction or less than 5 fractions with stereotactic guidance is called stereotactic radiotherapy. When compared to other radiotherapy modalities, the conformality of dose distribution is much better with stereotactic radiotherapy especially in tumors less than 4 cm. It is crucial to treat target volume with high precision in each fraction. Cyberknife (Accuray, Sunnyvale, CA) is a relatively new image-guided stereotactic radiosurgery and body radiotherapy device. It can irradiate the target from 1200 different angles. This enables us to treat the target with high precision and high dose while the organs at risk can be spared. Before performing imaging modalities for treatment planning, fudicials are placed in or around the target to identify the target volume and to track it during the treatment. In each treatment position the location of the target volume is verified with X ray images. If the images taken during treatment and the images obtained from treatment planning system matches the treatment begins. With the development of non-invasive stabilization mechanisms stereotactic radiotherapy modalities could be used in different parts of the body besides cranium. Primary and metastatic lung cancer, primary and metastatic liver cancer, pancreas cancer, recurrent head and neck cancer, recurrent gynecological cancer are examples of stereotactic body radiotherapy applications.