Dr. Hosang Jeon Profile

Dr. Hosang Jeon

Medical Physicist at Pusan National Univ

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Publications (7)

PROCEEDINGS ARTICLE | April 4, 2016

On the properties of artificial neural network filters for bone-suppressed digital radiography

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Tissues, Image processing, Digital filtering, Radiography, Electroluminescence, Bone, Artificial neural networks, Image filtering, Machine learning, Nonlinear filtering, Dual energy imaging, Network architectures, Neurons

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PROCEEDINGS ARTICLE | March 31, 2016

A framework for analytical estimation of patient-specific CT dose

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Statistical analysis, Chest, X-ray computed tomography, Signal attenuation, Calibration, Scanners, Photons, X-rays, Computer simulations, Image analysis, Monte Carlo methods, Head, Ray tracing, Computed tomography, Algorithm development

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PROCEEDINGS ARTICLE | March 30, 2016

Computed tomography with single-shot dual-energy sandwich detectors

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Optical filters, Sensors, X-rays, Copper, Photodiodes, Bone, Tomography, Image filtering, X-ray imaging, X-ray detectors

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PROCEEDINGS ARTICLE | March 30, 2016

Optimizing the CsI thickness for chest dual-shot dual-energy detectors

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Magnesium, Chest, Sensors, X-rays, Radiography, Modulation transfer functions, X-ray imaging, X-ray detectors, Signal detection, Dual energy imaging

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PROCEEDINGS ARTICLE | March 29, 2016

Analysis of the scatter effect on detective quantum efficiency of digital mammography

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Polymethylmethacrylate, Sensors, Photons, X-rays, Quantum efficiency, Quantum physics, Modulation transfer functions, Systems modeling, Digital mammography, Instrument modeling

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PROCEEDINGS ARTICLE | March 18, 2015

Physics-based modeling of computed tomography systems

Proc. SPIE. 9412, Medical Imaging 2015: Physics of Medical Imaging

KEYWORDS: X-ray computed tomography, Sensors, Photons, X-rays, Monte Carlo methods, Ray tracing, Algorithm development, X-ray imaging, X-ray detectors, Signal detection

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PROCEEDINGS ARTICLE | March 6, 2013

An experimental study on the shift-variant MTF of CT systems using a simple cylindrical phantom

Proc. SPIE. 8668, Medical Imaging 2013: Physics of Medical Imaging

KEYWORDS: Point spread functions, Imaging systems, Spatial frequencies, Image restoration, Computing systems, Fourier transforms, Radiotherapy, Computed tomography, Modulation transfer functions, Spatial resolution

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The modulation transfer function (MTF) is a typical parameter to measure the spatial resolution, which is an essential factor for evaluating the performance of computed tomography (CT) systems. It is known that the CT system does not follow the shift-invariant manner because of the cone-beam geometry and the transformation from the cylindrical coordinates to the axial coordinates when the image reconstruction is employed. Several studies reported that if the position of impulse receded from the center of a region of interest (ROI), the MTF degraded continuously. In this study, the trend of shift-variant characteristics of CT systems was measured and analyzed using a novel multi-cylindrical phantom. This study used to determine a point spread function (PSF) and MTF of a CT system using a simple cylindrical phantom. First of all, the optimal diameter of cylinder phantoms was experimentally determined as 70 mm to obtain reliable PSFs. Two kinds of field of views (FOVs), 40 cm and 60 cm, were used to vary reconstructed pixel sizes. The shift-variant MTF curves were acquired at five off-center positions per FOV. For the effective analysis of MTF shiftvariance, the integrated MTF values were calculated and used. In the result, the MTF slightly decreased as diameter increased from CT center in the central region within the distance of 10 cm. Moreover, a considerable MTF decrease suddenly occurred around the distance of 15 cm in the actual FOVs. The decreasing trend of the off-center spatial resolution of CT cannot be neglected in recent radiologic and radio-therapeutic fields requiring high degree of image precision, especially in sub-mm images. It is recommended that the ROI is laid on the CT center as close as possible. A novel cylindrical phantom was finally suggested to effectively measure PSFs with optimal diameters for clinical FOVs in this study. This phantom is cheap and convenient to use because it was only made of acryl with simple geometry. It is expected that the spatial resolution of CT can be easily monitored using our methodology in clinical CT sites.

Showing 5 of 7 publications

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