Measurement of angular correlation changes in double-photon emission nuclides using ultrasound irradiation

• Published in: Journal of instrumentation 2023-04, Vol.18 (4), p.C04001
• Main Authors: Sensui, F., Uenomachi, M., Shimazoe, K., Takahashi, H., Zhihong, Z., Ishijima, A., Nakagawa, K.
• Format: Article
• Language: English
• Subjects: Angular correlation; Aqueous solutions; Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc); Electric fields; Electric potential; Emission analysis; Gamma emission; Gamma rays; Interaction of radiation with matter; Irradiation; Nuclear medicine; Nuclides; Photomultiplier tubes; Photon emission; Photons; Point sources; Read out systems; Scintillation counters; Ultrasonic imaging; Ultrasonic testing; Voltage
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/18/04/C04001

Our group has been developing DPECT (Double Photon Emission CT) to enhance nuclear medicine diagnostics using cascade nuclides that emit multiple gamma rays simultaneously. It is possible to detect the local environment around the nuclide by examining the angular correlation of the emitted cascade gamma-rays. In this study, with the goal of developing a new imaging method combining ultrasound and nuclear medicine, we investigated the effect of ultrasound on cascade gamma-ray emission and found that the angular correlation could be changed by a micro-electric field around 111 In in an aqueous solution caused by ultrasound irradiation. Using 8 × 8 array of GAGG scintillators as a detector and Hamamatsu Photonics 8 × 8 MPPCs as a photomultiplier, eight detectors were used and arranged in a ring shape to surround the point source 111 In from 360° direction. For the readout system, using a dynamic ToT board, read out its channel information, energy information as ToT signal, and detection time information simultaneously and independently concerning gamma-ray detection. We measured the angular correlation change with four types of ultrasound intensities of 0.05 V, 0.10 V, 0.15 V, and 0.20 V input voltage, and found that the gamma-ray emission angle distribution decreased by about up to 5% around the 90° direction and increased by about up to 5% around 0° and 180° for an ultrasound with an input voltage of 0.15 V or higher.