SU‐E‐T‐159: Characteristics of Fiber‐Optic Radiation Sensor for Proton Therapeutic Beam

Abstract

Purpose: A fiber‐optic radiation sensor using Cerenkov radiation has been widely studied for use as a dosimeter for proton therapeutic beam. Although the fiber‐optic radiation sensor has already been investigated for proton therapeutic, it has been examined relatively little work for clinical therapeutic proton beams. In this study, we evaluated characteristics of a fiber‐optic radiation sensor for clinical therapeutic proton beams. We experimentally evaluated dose‐rate dependence, dose response and energy dependence for the proton beam. Methods: A fiber‐optic radiation sensor was placed in a water phantom. Beams with energies of low, middle and high were used in the passively‐scattered proton therapeutic beam at the National Cancer Center in Korea. The sensor consists of two plastic optical fibers (POF). A reference POF and 2 cm longer POF were used to utilize the subtraction method for having sensitive volume. Each POF is optically coupled to the Multi‐Anode Photo Multiplier Tube (MAPMT) and the MAPMT signals are processed using National Instruments Data Acquisition System (NI‐DAQ). We were investigated dosimetric properties including dose‐rate dependence, dose response and energy dependence. Results: We have successfully evaluated characteristics of a fiber optic radiation sensor using Cerenkov radiation. The fiber‐optic radiation sensor showed the dose response linearity and low energy dependence. In addition, as the dose‐rate was increased, Cerenkov radiation increased linearly. Conclusion: We evaluated the basic characteristics of the fiber optic radiation sensor, the dosimetry tool, to raise the quality of proton therapy. Based on the research, we developed a real time dosimetry system of the optic fiber to confirm the real time beam position and energy for therapeutic proton pencil beam.