Scintillating fiber arrays for in-vivo real-time patient quality assurance for medical linear accelerators

Abstract

The purpose of this research is to design real-time, in-vivo, transmission scintillating fiber detectors capable of identifying errors in external beam radiation therapy when a fraction of a treatment has been delivered. Two Cherenkov radiation corrected scintillating fiber detectors were constructed. These transmission detectors are fastened directly to the linac collimator using the accessory tray mount. One detector was developed for IMRT and consists of a linear array of 60 1.5mm square scintillating fibers aligned to the linac MLC leaf pairs. The second has higher resolution and is designed for SBRT/SRS. This real-time dosimeter is composed of two high-density orthogonal arrays of 128 0.5mm square fibers with a 0.8mm pitch and can capture angular projections to reconstruct 2D beam fluence with sub-millimetric resolution. The fibers are coupled to high-speed, high-gain optoelectronics and a high-speed analog-to-digital converter to process the output from each detector in real-time. The data is analyzed using in-house developed software to reconstruct the delivered dose and beam fluence. These novel detectors set a new benchmark for treatment accuracy and patient safety for radiation therapy treatments.