TA23-QA Process of Fractionated Stereotactic Radiotherapy (FSR)

Ching-Chong Jack Yang, PhD

Radiation Oncology Dept.

Monmouth Medical Center

300 2nd Ave

Long Branch, NJ 07740

Performing LINAC based Radiosurgery with invasive fixation device has been a very standard procedure and has taken advantages of the high localization accuracy. However, for tumors that are more sensitive to the fractionation treatment scheme, then the invasive immobilization lost its clinical usage. In order to acquire both high treatment precision and sharp dose gradient from Radiosurgery procedures, Fractionated Stereotactic Radiotherapy (FSR) provides another alternative methodology. QA of the FSR procedure remains similar to the single fraction treatment delivery, checking laser and patient repositioning accuracy from the calculated isocenter coordinates are necessary before each treatment delivery. Vendors or in-house developed tools or devices can also help to identify the patient treatment location for achieving high treatment precision. QA of FSR relies on careful alignment of the fiducial markers (either internal or external), laser system adjustment and calibration (table mounted system), isocenter verification, and treatment delivery verification. Another important item for FSR QA is the collision test, which not only verified in planning system, but also in the treatment delivery phase since arc therapy with couch angles is always critical in QA verification.