LAUSR

A miniature optical fiber real-time X-ray radiation sensor based on plastic optical fiber coupled with a fast decay time trivalent cerium-activated yttrium aluminum garnet Y3Al5O12 (YAG:Ce) scintillator material is reported. The YAG material was tested in powder and ceramic form. Three separate sensors were irradiated three times on a Siemens Artiste linear accelerator (linac). The measured light output of the YAG:Ce ceramic to the detector at the distal end of the fiber is 4.52 times greater than the YAG:Ce powder, and its output intensity detected by photon counter is further increased 2.52 times using a two-layer highly reflective Teflon tape. The sensor made with YAG:Ce powder shows excellent repeatability, being a maximum of 0.36 %, but the value using YAG:Ce ceramic exhibits orientation sensitivity when located in orthogonal positions relative to the X-ray beam. To the best of our knowledge, the work described in this letter is the first instance of the direct high temporal resolution detection of the individual (circa 3.9 ms) output of X-ray light pulses of clinical linacs. The experimental results of pulsewidths are in good agreement with the manufacturer’s stated value of $3.45~\pm ~0.21~\mu \text{s}$ .