Radiation-induced light in optical fibers and plastic scintillators: application to brachytherapy dosimetry

Abstract

Abstruct-A small plastic scintillator bonded to an optical fiber has several characteristics that make it promising as a brachytherapy dosimeter. In these dosimeters, scintillation light represents signal, whereas Cerenkov and luminescence light from the optical fiber stem is noise that must be subtracted. The dosimeter accuracy can be improved by optically filtering part of the fiber stem light. Spectral measurements were performed to guide the choice of scintillator, fiber, and filter. Spectral signatures and total luminescence of three scintillators and five different silica optical fibers, excited by a 8 Ci I9'Ir source, were measured. The total radiation-induced light from the various optical fibers differed by up to a factor of 5.6. The percentage of fiber-produced light due to luminescence varied between 15 and 79%. A fiber with weak emission was used in the dosimeter with BC408S, a scintillator with minimum emission wavelength of 400 nm. A 400-nm cutoff UV filter gave a factor of two increase in signal-to-noise. The dosimeter response was linear for dose rates varying by at least three orders of magnitude, representing source-to-probe distances of 0.2-10 cm. Measurement errors of the dosimeter compare favorably with other brachytherapy dosimeters.

Towards two-dimensional brachytherapy dosimetry using plastic scintillator: New highly efficient water equivalent plastic scintillator materials

“…The need for a highly efficient radiation dosimeter for radiotherapy has prompted many investigators to study and use plastic scintillator as a real time detector. [1][2][3][4][5][6] While all these studies used plastic scintillator ͑PS͒ as a single element dosimeter, i.e., measuring radiation dose at one point in space at a time ͑except the work of Olde and Brannen, 6 in which the scintillation light was integrated over an area͒, our group has endeavored to create a two-dimensional PS dosimeter by observing the light emitted by a plastic scintillator sheet. [7][8][9][10][11] In either case, high accuracy dosimetric measurements in low-energy photon fields requires PS material with radiological properties approximating those of water.…”

Characterizing energy dependence and count rate performance of a dual scintillator fiber‐optic detector for computed tomography

“…fiber medium. 18,19 This reference fiber was positioned adjacent and parallel to other fibers to quantify all stem counts originating in the scintillator waveguide. These stem counts were subtracted from the measured signal in the detector fibers.…”

Measurements of Relative Depth Doses Using Fiber-Optic Radiation Sensor and EBT Film for Brachytherapy Dosimetry

“…The first is based on removing Cerenkov light using a background dummy fiber without employing an organic scintillator [14]- [16]. In this method, real scintillating light is obtained by subtracting Cerenkov light generated in the dummy fiber.…”