Patient positioning based on a radioactive tracer implanted in patients with localized prostate cancer: a performance and safety evaluation.

Purpose: To evaluate the performance and safety of a radiation therapy positioning system (RealEye) based on tracking a radioactive marker (Tracer) implanted in patients with localized prostate cancer.

Methods And Materials: We performed a single-arm multi-institutional trial in 20 patients. The iridium-192 ((192)Ir)-containing Tracer was implanted in the patient together with 4 standard gold seed fiducials.