Characterization of a Low-Cost Plastic Fiber Array Detector for Proton Beam Dosimetry

Abstract

The Pencil Beam Scanning (PBS) technique in proton therapy uses fast magnets to scan the tumor volume rapidly. Changing the proton energy allows changing to layers in the third dimension, hence scanning the same volume several times. The PBS approach permits adapting the speed and/or current to modulate the delivered dose. We built a simple prototype that measures the dose distribution in a single step. The active detection material consists of a single layer of scintillating fibers (i.e., 1D) with an active length of 100 mm, a width of 18.25 mm, and an insignificant space (20 μm) between them. A commercial CMOS-based camera detects the scintillation light. Short exposure times allow running the camera at high frame rates, thus, monitoring the beam motion. A simple image processing method extracts the dose information from each fiber of the array. The prototype would allow scaling the concept to multiple layers read out by the same camera, such that the costs do not scale with the dimensions of the fiber array. Presented here are the characteristics of the prototype, studied under two modalities: spatial resolution, linearity, and energy dependence, characterized at the Center for Proton Therapy (Paul Scherrer Institute); the dose rate response, measured at an electron accelerator (Swiss Federal Institute of Metrology).

A Multi-Point Optical Fibre Sensor for Proton Therapy

“…Radiotherapy systems employing or potentially benefiting from multipoint sensing range from particle radiotherapy [1][2][3] to brachytherapy [4][5][6][7][8][9] and teletherapy [10][11][12][13]. The simultaneous, real-time monitoring of multiple points inside and outside of an irradiated volume using fibre-based sensors is currently under investigation by several groups with some success, namely in the form of the commercially available Hyperscint™ scintillator dosimeter [14]-a system that utilises a spectrometer and employs a spectral separation method to chromatically remove induced Čerenkov and fluorescence from the total signal [15][16][17].…”

“…To date, though proton therapy is increasing in treatment sites and frequency [23], options available for multipoint sensing in protons, both pencil-beam scanned and passively scattered, are largely based on electronic sensors acting as both dosimeter and digitizer and therefore are located in the irradiation chamber [2,[24][25][26], exposing sensitive elements to damaging radiation. A reuseable array where the sensing material is not subject to radiation damage and is (relatively) easily replaced at low cost, such as small volumes of plastic optical fibre scintillators with long extensions leading to electronics outside of the irradiation chamber, would provide a cost-effective and long-lasting solution.…”

Organic Scintillator-Fibre Sensors for Proton Therapy Dosimetry: SCSF-3HF and EJ-260

“…Both scintillating materials have been and continue to be studied for radiation detection, dosimetry, and monitoring applications [25][26][27][28][29][30]. In addition, a number of scintillator fibre sensors, both organic and inorganic, have been investigated for their dosimetric potential in proton and neutron radiation [31][32][33][34][35][36][37][38][39][40]; however, thus far, the proposed specific use of these materials has not yet been explored.…”

Development, Characterization and Valuable Use of Novel Dosimeter Film Based on PVA Polymer Doped Nitro Blue Tetrazolium Dye and AgNO3 for the Accurate Detection of Low X-ray Doses

“…Furthermore, having a lightweight, portable and easy-to-handle dosimeter is very required and advantageous. The most suitable choice was the use of thin films based on different polymers [ 23 , 24 ]. Numerous researches and publications have reported the investigation of polyamide-6, polyvinyl alcohol and polystyrene films dopped with various dyes, in the detection of various types of radiation [ 25 , 26 , 27 ].…”