Room: Exhibit Hall | Forum 8
Purpose: To characterize attenuation, bending losses and response to positrons for a dual readout scintillating fiber-based wrist detection system developed to determine the arterial input function in PET.
Methods: The scintillating fiber was excited by ultraviolet (UV) and gamma radiation (Â¹Â³â?·Cs, 186.5 kBq). The excitation sources were placed at different positions along the scintillating fiberâ€™s axis. The ratio of the signals on both ends was fitted to a mono-exponential function to determine the attenuation lengths. Since the detector will be wrapped around the wrist, signal losses for different bending radii were evaluated. The output ratio for loops with different radii were compared with the corresponding ratio of a straight fiber to determine potential signal losses. Furthermore, two scenarios were investigated with 100 ÂµCi/ml of Â¹â?¸F solution injected in a polyethylene wrist-phantom; A) stationary case where the solution was injected inside the phantom, B) flow of the solution entering and exiting the phantom.
Results: The attenuation lengthÂ of the light emitted by the UV and Â¹Â³â?·Cs sources in the scintillating fiber was 146Â±6 cm and 169Â±9 cm respectively. Attenuation depends on the wavelength. The excitation sources may not result in the same excitation spectrum, which can explain the difference in attenuation between the sources. Bending losses with Â¹Â³â?·Cs were smaller than the measurementsâ€™ uncertainty, while for the UV, measured losses rangedÂ from 0.82% with radius of 15 cm to 2.20% at 6 cm. For scenario A with the Â¹â?¸F, the maximum signal in the phantom occurred after 1min-25,7sec. For scenario B, the solution was present in the phantom from 17.9 to 38.0 seconds.
Conclusion: This preliminary study demonstrated the feasibility and robustness of the detector set-up. In future studies, phantom measurements resembling clinical cases with realistic input function will be carried out prior to testing the detector on patients.
Funding Support, Disclosures, and Conflict of Interest: Funding: Vincent Turgeon acknowledges partial support by the CREATE Medical Physics Research Training Network grant of the Natural Sciences and Engineering Research Council (Grant number: 432290) and the "Fonds de recherche Nature et technologies Quebec" (Grant number 199601)