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Son Kihong,Kim Jin Sung,Kao Chien-Min,Cho Seungryong 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.11
A real-time dose-guidance is highly desirable for monitoring the accuracy of the radiation treatment during irradiation. We present a sequentially processed image reconstruction algorithm (SPIRA) for in-beam TOF-PET that has the potential to provide concurrent imaging of the positron distributions from list-mode TOF-PET data in particle therapy. The SPIRA employs the maximum-likelihood (ML) criterion and reconstructs an image in the continuous-coordinate event space. In parallel, a serial processor (SP) is adopted to support concurrent imaging. The algorithm has been applied to computer simulation data generated for its potential use in in-beam TOF-PET monitoring of dose distributions in proton therapy, including a full-ring system and a dual-head partial-ring system. We considered various coincidences resolving times (CRTs) for the systems including 300 ps and 600 ps. Two opening angles Ø, 45 and 90°, were considered in the partial-ring geometry. The images generated by the SPIRA appear to provide better resolution and contrast recovery than by the conventional image reconstruction method in which the events are simply placed at the computed positions based on the TOF measurement. We believe that SPIRA can be useful for in vivo treatment verifcation in a real-time dose-guided particle therapy.
Kihong Son,Seunghyung Lee,Hyobin Lee,Yejin Lee,Dongwook Son,Seunghyeon Myeong,Minjoo Chang,Daehong Kim,Myung-Ae Chung 한국자기학회 2023 Journal of Magnetics Vol.28 No.4
This simulation study aims to differentiate between contrast media and calcification in blood vessel using the effective atomic number (EAN) extraction method in electromagnetic X-ray computed tomography (CT) imaging. Calibration was performed on six tissue-equivalent materials, three contrast medium, and one calcium solution. The Hounsfield unit (HU) values at 80 kV and 140 ㎸ with electromagnetic spectrum using dualenergy computed tomography (DECT) facilitated this calibration. EAN from the polynomial method was then compared with that from the Stoichiometric method. In 120 ㎸ vascular imaging, when the HU of calcium and iodine contrast media were alike, EAN provided a more pronounced contrast than HU. The iodine contrast agent’s enhancement in EAN was approximately 30.0 %, and in HU, it was 13.0 % relative to calcium. This indicates EAN’s potential to better differentiate contrast media from calcification in clinical contexts.
Son, Kihong,Cho, Seungryong,Kim, Jin Sung,Han, Youngyih,Ju, Sang Gyu,Choi, Doo Ho unknown 2014 Journal of applied clinical medical physics Vol.15 No.2
<P>Image‐guided techniques for radiation therapy have improved the precision of radiation delivery by sparing normal tissues. Cone‐beam computed tomography (CBCT) has emerged as a key technique for patient positioning and target localization in radiotherapy. Here, we investigated the imaging radiation dose delivered to radiosensitive organs of a patient during CBCT scan. The 4D extended cardiac‐torso (XCAT) phantom and Geant4 Application for Tomographic Emission (GATE) Monte Carlo (MC) simulation tool were used for the study. A computed tomography dose index (CTDI) standard polymethyl methacrylate (PMMA) phantom was used to validate the MC‐based dosimetric evaluation. We implemented an MC model of a clinical on‐board imager integrated with the Trilogy accelerator. The MC model's accuracy was validated by comparing its weighted CTDI (CTDIw) values with those of previous studies, which revealed good agreement. We calculated the absorbed doses of various human organs at different treatment sites such as the head‐and‐neck, chest, abdomen, and pelvis regions, in both standard CBCT scan mode (125 kVp, 80 mA, and 25 ms) and low‐dose scan mode (125 kVp, 40 mA, and 10 ms). In the former mode, the average absorbed doses of the organs in the head and neck and chest regions ranged 4.09‐8.28 cGy, whereas those of the organs in the abdomen and pelvis regions were 4.30‐7.48 cGy. In the latter mode, the absorbed doses of the organs in the head and neck and chest regions ranged 1.61‐1.89 cGy, whereas those of the organs in the abdomen and pelvis region ranged between 0.79‐1.85 cGy. The reduction in the radiation dose in the low‐dose mode compared to the standard mode was about 20%, which is in good agreement with previous reports. We opine that the findings of this study would significantly facilitate decisions regarding the administration of extra imaging doses to radiosensitive organs.</P><P>PACS number: 87.57.uq</P>
Beam line design and beam transport calculation for the μSR facility at RAON
Pak, Kihong,Park, Junesic,Jeong, Jae Young,Kim, Jae Chang,Kim, Kyungmin,Kim, Yong Hyun,Son, Jaebum,Lee, Ju Hahn,Lee, Wonjun,Kim, Yong Kyun Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10
The Rare Isotope Science Project was launched in 2011 in Korea toward constructing the Rare isotope Accelerator complex for ON line experiments (RAON). RAON will house several experimental systems, including the Muon Spin Rotation/Relaxation/Resonance (μSR) facility in High Energy Experimental Building B. This facility will use 600-MeV protons with a maximum current of 660 pμA and beam power of 400 kW. The key μSR features will facilitate projects related to condensed-matter and nuclear physics. Typical experiments require a few million surface muons fully spin-polarized opposite to their momentum for application to small samples. Here, we describe the design of a muon transport beam line for delivering the requisite muon numbers and the electromagnetic-component specifications in the μSR facility. We determine the beam-line configuration via beam-optics calculations and the transmission efficiency via single-particle tracking simulations. The electromagnet properties, including fringe field effects, are applied for each component in the calculations. The designed surface-muon beamline is 17.3 m long, consisting of 2 solenoids, 2 dipoles affording 70° deflection, 9 quadrupoles, and a Wien filter to eliminate contaminant positrons. The average incident-muon flux and spin rotation angle are estimated as 5.2 × 10<sup>6</sup> μ<sup>+</sup>/s and 45°, respectively.
채승훈,Kihong Son,이수열 한국전자통신연구원 2022 ETRI Journal Vol.44 No.5
Nondestructive testing, which can monitor a product’s interior without disassembly, is becoming increasingly essential for industrial inspection. Computed laminography (CL) is widely used in this application, as it can reconstruct a product, such as a printed circuit board, into a three-dimensional (3D) highmagnification image using X-rays. However, such high-magnification scanning environments can be affected by minute vibrations of the CL device, which can generate motion artifacts in the 3D reconstructed image. Since such vibrations are irregular, geometric corrections must be performed at every scan. In this paper, we propose a geometry calibration method that can correct the geometric information of CL scans based on the image without using geometry calibration phantoms. The proposed method compares the projection and digitally reconstructed radiography images to measure the geometric error. To validate the proposed method, we used both numerical phantom images at various magnifications and images obtained from real industrial CL equipment. The experiment results confirmed that sharpness and contrast-to-noise ratio (CNR) were improved.