Radioluminescence of some optical fibres

Area of Science:

• Medical Physics
• Materials Science
• Radiological Imaging

Background:

• Scintillator-based radiation detectors offer an attractive method for measuring radiation fields and dose.
• A key challenge is discriminating scintillator luminescence from unwanted signals, particularly radioluminescence from optical fibers used for signal transmission in diagnostic radiology.

Purpose of the Study:

• To identify optical fibers with low radioluminescence suitable for use with scintillator detectors in diagnostic radiology.
• To compare the radioluminosity of various commercial optical fiber materials, including polystyrene, polystyrene wavelength shifting fibers, PMMA, and silica.

Main Methods:

• A survey of ten commercial optical fibers was conducted.
• Measurements utilized two photomultipliers with different spectral responses and a clinical X-ray unit to assess radioluminescence.
• Fiber core materials investigated included polystyrene (PS), PMMA, and silica.

Main Results:

• Poly-methylmethacrylate (PMMA) fibers demonstrated the lowest radioluminescence.
• Clear polystyrene (PS) fibers produced five to ten times more luminescence than PMMA fibers, depending on the photomultiplier's spectral sensitivity.
• Only one high-OH silica fiber showed comparable low luminescence up to 520 nm; low-OH silica and wavelength-shifting fibers exhibited high fluorescence and were unsuitable.

Conclusions:

• PMMA optical fibers are the most suitable material for transmitting scintillator signals in diagnostic radiology due to their minimal radioluminescence.
• The selection of optical fibers is critical for minimizing signal impairment in scintillator-based radiation dose measurements.
• Wavelength shifting and low-OH silica fibers are not recommended for this application because of their significant fluorescence.