Kenji Shimazoe

The time over threshold (TOT) method has several advantages over direct pulse height analysis based on analog to digital converters (ADCs). A key advantage is the simplicity of the conversion circuit which leads to a high level of integration and a low power consumption. The TOT technique is well suited to build multi-channel readout systems for pixelated detectors as described in our previous work that also exploits the Pulse Width Modulation (PWM) method. The main limitation of the TOT techniq

Positron-emission tomography (PET) and single-photon-emission computed tomography (SPECT) are well-established nuclear-medicine imaging methods used in modern medical diagnoses. Combining PET with ¹⁸F-fluorodeoxyglucose (FDG) and SPECT with an ¹¹¹In-labelled ligand provides clinicians with information about the aggressiveness and specific types of tumors. However, it is difficult to integrate a SPECT system with a PET system because SPECT requires a collimator. Herein, we d

Single photon emission computed tomography(SPECT) is a useful medical imaging modality using single photon detection from radioactive tracers, such as 99Tc and 111In, however further development of increasing the contrast in the image is still under investigation. A novel method (Double Photon Emission CT / DPECT) using a coincidence detection of two cascade gamma-rays from 111In is proposed and characterized in this study. 111In, which is well-known and commonly used as a SPECT tracer, emits tw

Abstract Single-photon-emission computed tomography (SPECT) and positron-emission tomography (PET) are highly sensitive molecular detection and imaging techniques that generally measure accumulation of radio-labeled molecules by detecting gamma rays. Quantum sensing of local molecular environment via spin, such as nitrogen vacancy (NV) centers, has also been reported. Here, we describe quantum sensing and imaging using nuclear-spin time-space correlated cascade gamma-rays via a radioactive trace

We have developed Time over Threshold (ToT) based Pr:LuAG-APD PET (TODPET) tomograph with a mixed signal front-end. The tomograph consists of 8 block detectors, each of which is composed of a 12 × 12 array of 2 × 2 x 10mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> Pr:LuAG crystals individually coupled with 12 × 12 UV-enhanced APD arrays. The APDs are individually read out with a custom-designed Time over Threshold ASIC and FPGA readout

The architecture of a multi-channel front-end system is important for realizing a high-resolution PET system. We propose a novel front-end pulse processing scheme with pulse width modulation (PWM) and pulse train method for PET systems. Each channel of the proposed system consists of a preamplifier, a shaping amplifier, a comparator, and a digital circuit that generates a pulse train for each event. The preamplifier-shaper-discriminator module first generates a trigger pulse with time-over-thres

Abstract Multi-molecule imaging and inter-molecular imaging are not fully implemented yet, however, can become an alternative in nuclear medicine. In this review article, we present arguments demonstrating that the advent of the Compton positron emission tomography (Compton-PET) system and the invention of the quantum chemical sensing method with double photon emission imaging (DPEI) provide realistic perspectives for visualizing inter-molecular and multi-molecule in nuclear medicine with MeV ph

Quantum technology, such as the quantum computers, has attracted significant attention in recent years. In nuclear medicine, powerful and highly sensitive molecular imaging modalities such as PET (Positron Emission Tomography), SPECT (Single Photon Emission CT) and MRI (Magnetic Resonance Imaging) provide accurate morphological and functional information. Exploiting certain aspects of quantum mechanics may bring further improvements in sensitivity, spatial resolution and enable novel capabilitie

Depth of interaction (DOI) information is important in the development of high-resolution detectors as it helps to reduce parallax error in positron emission tomography (PET) systems. Further, the determination of depth in the crystal is important for making scintillation crystal-based detectors in many other applications, such as the Compton imager and multi-radiation imagers. In this paper, a novel DOI method based on discrimination of the wavelength of the scintillation light emitted from a s

Compton imaging is a useful method for localizing sub MeV to a few MeV gamma-rays and widely used for environmental and medical applications. The direction of recoiled electrons in Compton scattering process provides the additional information to limit the Compton cones and increases the sensitivity in the system. The capability of recoiled electron tracking using trigger-mode Silicon-On-Insulator (SOI) sensor is investigated with various radiation sources. The trigger-mode SOI sensor consists o

X-ray photon-counting computed tomography (PCCT) has garnered considerable interest owing to its low-dose administration, high-quality imaging, and material decomposition characteristics. Current commercial PCCT systems employ compound semiconductor photon-counting X-ray detectors, which offer good energy resolution. However, the choice of materials is limited, and cadmium telluride or cadmium zinc telluride is mostly used. Although indirect radiation detectors can be used as alternatives to com