A Multi-Point Optical Fibre Sensor for Proton Therapy

Abstract

As the technology to deliver precise and very high radiotherapeutic doses with narrow margins grows to better serve patients with complex radiotherapeutic needs, so does the need for sensors and sensor systems that can reliably deliver multi-point dose monitoring and dosimetry for enhanced safety and access. To address this need, we investigated a novel five-point scintillator system for simultaneously sampling points across a 74 MeV proton beam with a Hamamatsu 16-channel MPPC array. We studied the response across beam widths from 25 mm down to 5 mm in diameter and in multiple depths to observe beam penumbrae and output factors as well as depth–dose. We found through comparison to ionization chambers and radiochromic film that the array is capable of measurements accurate to within 8% in the centre of proton beams from 5 to 25 mm in diameter, and within 2% at 3.5 cm depth in water. The results from three trials are repeatable after calibration to within <1%. Overall, the five optical fibre sensor system shows promise as a fast, multipoint relative dosimetry system.