Initial results of in vivo CT imaging of contrast agents using MPPC-based photon-counting CT

Sato, Daichi; Arimoto, M.; Yoshiura, Kotaro; Mizuno, Tomoya; Aiga, Ko; Ishiguro, Kairi; Tomoda, Takahiro; Kawashima, Hiroki; Kobayashi, Satoshi; Okumura, Kenichiro; Murakami, Kazuhiro; Kataoka, J.; Toyoda, T.; Sagisaka, Mayu; Terazawa, Shinsuke; Shiota, Susumu

doi:10.1016/j.nima.2022.167960

Cited by 11 publications

(4 citation statements)

References 9 publications

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“…The light yield of the YGAG scintillator is ∼50000 photons/MeV. Here, the YGAG scintillator was employed for various applications, such as X-ray computed tomography imaging [6,7]. During the experiment, the YGAG scintilator endured X-ray irradiation for over 1000 hours, using an X-ray generator with a tube voltage of 100 kV and a tube current of 0.5 mA.…”

Section: Gamma-ray Detectormentioning

confidence: 99%

Multi-pixel photon counter-based gamma camera with pinhole collimator to locate Cs-137 sources at high dose rates for the Fukushima nuclear power plant

Tomoda,

Arimoto,

Mizuno

et al. 2024

J. Inst.

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The Fukushima Daiichi Nuclear Power Plant was severely damaged during the 2011 Great East Japan Earthquake. However, the ongoing decommissioning work has been limited by the complexity of the reactor's internal structure and very high radiation levels; locating radioactive sources is essential for efficient decommissioning. Conventional gamma cameras are mainly designed for low radiation dose (∼mSv/h) and using them under high radiation conditions is difficult (>Sv/h). Therefore, we developed a pinhole gamma camera with a gamma radiation detector consisting of a high-speed YGAG scintillator array and multi-pixel photon counters to locate radioactive sources at high dose rates. The gamma-ray photon signals captured by the developed two-dimensional detector array can be processed at a speed as high as >1 MHz/pixel using the developed large scale integrated circuit. Herein, we report the measurement results of an extremely high radioactivity of 137Cs (∼34 TBq) using the developed gamma camera. The gamma-ray source position was determined using an angular size of ∼4.6°, with images obtained at 2 m from the radioactive source and at a dose rate of 0.3 Sv/h. The direct gamma rays with a photoelectric peak at 662 keV and scattered component of gamma rays can be distinguished from the measured spectrum. We also characterize the imaging capability of the 137Cs depending on the detected gamma-ray energies and discuss related details.

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Section: Gamma-ray Detectormentioning

confidence: 99%

Multi-pixel photon counter-based gamma camera with pinhole collimator to locate Cs-137 sources at high dose rates for the Fukushima nuclear power plant

Tomoda,

Arimoto,

Mizuno

et al. 2024

J. Inst.

Self Cite

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“…As shown in figure 5, the SSIM indices between the CT images without downsampling and those with downsampling ratios of 1/10 or more (i.e., 20, 25, 40, 50, and 100 projections) were ≳0.90 for the rod phantoms. In addition, the iodine concentration maps were calculated, as shown on the left side of figure 6; details of the concentration estimate method can be obtained from the literature [13]. The obtained SSIMs of the concentration maps were ≳0.90, with downsampling ratios of 1/10 or more.…”

Section: Static Phantom Imagingmentioning

confidence: 99%

“…In this study, we obtained the initial results of a quality evaluation of sparse-view CT images that were acquired using the PC-CT system. Static phantoms equivalent to an iodine-containing contrast agent and a mouse model injected with an iodine-containing contrast agent were prepared as subjects; these were previously used for image analysis with FBP [11][12][13]. CT scanning was then performed, and a CS-based image-reconstruction algorithm with the total-variation (TV) minimization was applied to the sparsely sampled projection data with various downsampling ratios.…”

Section: Introductionmentioning

confidence: 99%

Sparse-view image reconstruction with total-variation minimization applied to sparsely sampled projection data from SiPM-based photon-counting CT

Sato,

Arimoto,

Kotoku

et al. 2024

J. Inst.

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We constructed a sparse-view computed tomography (CT) system that combines a compressed sensing (CS)-based image-reconstruction algorithm and SiPM-based photon-counting (PC) CT. CS-based image-reconstruction algorithms have been extensively studied for X-ray CT image reconstruction using fewer projections because they are expected to reduce CT imaging time and radiation exposure while maintaining CT image quality. In most previous studies, CS-based image-reconstruction algorithms have been applied to data obtained through numerical simulations or conventional dual-energy CT. However, studies on PC-CT have been scarce. Therefore, we applied a CS-based image-reconstruction algorithm to the projection data obtained using our previously established SiPM-based PC-CT system and evaluated its image quality. We prepared static phantoms equivalent to iodine-containing contrast agents and a mouse model injected with iodine-containing contrast agents as subjects. Thereafter, CT scanning was performed. The obtained projection data were downsampled to simulate a sparse-view situation, and a CS-based image-reconstruction algorithm with total-variation minimization was applied. Consequently, sparse-view CT images were successfully reconstructed, and the image quality was maintained even after downsampling the projection data (downsampling ratios of 1/10 and 1/2 for the rod phantom and mouse model, respectively). Thus, the imaging time and exposure dose could be remarkably reduced (by a factor of 10 or 2), indicating that the CS-based image-reconstruction algorithm is effective for PC-CT.

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“…To do so, it is necessary to identify the exact location of the disease within the body. Imaging is effective in this identification owing to its high-contrast, clear images; X-ray contrast agents are an example of this type of technology [1][2][3]. A solution of iodine compounds is the most common commercially available X-ray contrast agent.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Single Nanometer-Sized Au Nanoparticles Coated with Silica Toward X-Ray Contrast Agent

Sakamoto,

Yamauchi,

Takase

et al. 2023

SSP

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In this study, we proposed a method for fabricating diagnostic imaging nanoparticles composed of Au nanoparticles and silica shells (Au/SiO2). The proposed method consisted of two steps. The first step was the synthesis of Au nanoparticles. In sodium hydroxide (NaOH) solution, hydrogen tetrachloroaurate (III) trihydrate was reduced with tetrakis(hydroxymethyl)phosphonium chloride to synthesize Au nanoparticles with a diameter of 1.7 ± 0.3 nm. The Au nanoparticles were then coated with silica in the following step. The silica coating was achieved via a sol–gel reaction of tetraethyl orthosilicate in the presence of Au nanoparticles in water/ethanol dissolved in NaOH. The Au/SiO2 nanoparticles degraded faster in saline or phosphate-buffered saline than in water, and the X-ray imaging capability was retained.

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Initial results of in vivo CT imaging of contrast agents using MPPC-based photon-counting CT

Cited by 11 publications

References 9 publications

Multi-pixel photon counter-based gamma camera with pinhole collimator to locate Cs-137 sources at high dose rates for the Fukushima nuclear power plant

Multi-pixel photon counter-based gamma camera with pinhole collimator to locate Cs-137 sources at high dose rates for the Fukushima nuclear power plant

Sparse-view image reconstruction with total-variation minimization applied to sparsely sampled projection data from SiPM-based photon-counting CT

Synthesis of Single Nanometer-Sized Au Nanoparticles Coated with Silica Toward X-Ray Contrast Agent

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