Prof. Youngjin Lee Profile

Prof. Youngjin Lee

Professor at Gachon Univ

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Publications (15)

Proceedings Article | 16 March 2020 Paper

Effect of geometric variations on image characteristics in digital tomosynthesis

Seungwan Lee, Burnyoung Kim, Dobin Yim, Youngjin Lee

Proceedings Volume 11312, 113122D (2020) https://doi.org/10.1117/12.2543148

KEYWORDS: Image quality, Imaging systems, X-ray sources, Image analysis, Spatial resolution, Modulation transfer functions, Digital imaging, Sensors, Spatial frequencies, 3D image processing

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Proceedings Article | 1 March 2019 Paper

Improvement of material decomposition accuracy using denoising and deblurring techniques in spectral mammography

Jisoo Eom, Burnyoung Kim, Wonhyung Kim, Youngjin Lee, Seungwan Lee

Proceedings Volume 10948, 109485N (2019) https://doi.org/10.1117/12.2512680

KEYWORDS: Denoising, Modulation transfer functions, Spatial resolution, Mammography, Image quality, Digital mammography, Monte Carlo methods, Image processing

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Proceedings Article | 9 March 2017 Paper

Performance evaluation of algebraic reconstruction technique (ART) for prototype chest digital tomosynthesis (CDT) system

Haenghwa Lee, Sunghoon Choi, Byungdu Jo, Hyemi Kim, Donghoon Lee, Dohyeon Kim, Seungyeon Choi, Youngjin Lee, Hee-Joung Kim

Proceedings Volume 10132, 101325V (2017) https://doi.org/10.1117/12.2255647

KEYWORDS: Chest, Reconstruction algorithms, Image quality, Radiography, Tumors, Algorithm development, Sensors, Health sciences, Opacity

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Proceedings Article | 18 March 2015 Paper

Feasibility of ray- and pixel-driven projector/back-projector in linear motion tomosynthesis

Sunghoon Choi, Seungwan Lee, Young-Jin Lee, Ye-Seul Kim, Haeng-Hwa Lee, Hee-Joung Kim

Proceedings Volume 9412, 94122Q (2015) https://doi.org/10.1117/12.2081132

KEYWORDS: Projection systems, X-rays, Systems modeling, Reconstruction algorithms, Sensors, Medical imaging, X-ray imaging, Ions, Neodymium, Tomography

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Proceedings Article | 18 March 2015 Paper

Evaluation of effective dose with chest digital tomosynthesis system using Monte Carlo simulation

Dohyeon Kim, Byungdu Jo, Youngjin Lee, Su-Jin Park, Dong-Hoon Lee, Hee-Joung Kim

Proceedings Volume 9412, 94125D (2015) https://doi.org/10.1117/12.2081778

KEYWORDS: Monte Carlo methods, Chest, Lung, Spine, Heart, X-rays, Bone, Tomography, Radiography, Imaging systems

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Proceedings Article | 18 March 2015 Paper

Detection of lung nodules in chest digital tomosynthesis (CDT): effects of the different angular dose distribution

Byungdu Jo, Youngjin Lee, Dohyeon Kim, Dong-Hoon Lee, Seong-Soo Jin, Shou-Chih Mu, Hye-Mi Kim, Hee-Joung Kim

Proceedings Volume 9412, 94125C (2015) https://doi.org/10.1117/12.2081767

KEYWORDS: Lung, Image quality, Chest, Imaging systems, Reconstruction algorithms, Image acquisition, Photons, Image processing, X-rays, Tomography

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Proceedings Article | 18 March 2015 Paper

An experimental study of the accuracy in measurement of modulation transfer function using an edge method

Dong-Hoon Lee, Ye-seul Kim, Hye-Suk Park, Young-Jin Lee, Hee-Joung Kim

Proceedings Volume 9412, 94123B (2015) https://doi.org/10.1117/12.2081370

KEYWORDS: Modulation transfer functions, Medical imaging, Smoothing, Image analysis, Sensors, Radiography, Spatial frequencies, Distortion, X-rays, Quantum efficiency

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Proceedings Article | 31 March 2014 Paper

Scatter correction method with primary modulator for dual energy digital radiography: a preliminary study

Byung-Du Jo, Young-Jin Lee, Dae-Hong Kim, Pil-Hyun Jeon, Hee-Joung Kim

Proceedings Volume 9033, 90335U (2014) https://doi.org/10.1117/12.2043016

KEYWORDS: Modulators, Dual energy imaging, Aluminum, Modulation, Monte Carlo methods, Polymethylmethacrylate, Radiography, Image quality, X-rays, Imaging systems

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In conventional digital radiography (DR) using a dual energy subtraction technique, a significant fraction of the detected photons are scattered within the body, resulting in the scatter component. Scattered radiation can significantly deteriorate image quality in diagnostic X-ray imaging systems. Various methods of scatter correction, including both measurement and non-measurement-based methods have been proposed in the past. Both methods can reduce scatter artifacts in images. However, non-measurement-based methods require a homogeneous object and have insufficient scatter component correction. Therefore, we employed a measurement-based method to correct for the scatter component of inhomogeneous objects from dual energy DR (DEDR) images. We performed a simulation study using a Monte Carlo simulation with a primary modulator, which is a measurement-based method for the DEDR system. The primary modulator, which has a checkerboard pattern, was used to modulate primary radiation. Cylindrical phantoms of variable size were used to quantify imaging performance. For scatter estimation, we used Discrete Fourier Transform filtering. The primary modulation method was evaluated using a cylindrical phantom in the DEDR system. The scatter components were accurately removed using a primary modulator. When the results acquired with scatter correction and without correction were compared, the average contrast-to-noise ratio (CNR) with the correction was 1.35 times higher than that obtained without correction, and the average root mean square error (RMSE) with the correction was 38.00% better than that without correction. In the subtraction study, the average CNR with correction was 2.04 (aluminum subtraction) and 1.38 (polymethyl methacrylate (PMMA) subtraction) times higher than that obtained without the correction. The analysis demonstrated the accuracy of scatter correction and the improvement of image quality using a primary modulator and showed the feasibility of introducing the primary modulation technique into dual energy subtraction. Therefore, we suggest that the scatter correction method with a primary modulator is useful for the DEDR system.

Proceedings Article | 19 March 2014 Paper

Projection-based energy weighting on photon-counting X-ray images in digital subtraction mammography: a feasibility study

Sung-Hoon Choi, Seung-Wan Lee, Yu-Na Choi, Young-Jin Lee, Hee-Joung Kim

Proceedings Volume 9033, 90334B (2014) https://doi.org/10.1117/12.2043035

KEYWORDS: Iodine, Digital mammography, Sensors, Photodetectors, Tumors, X-rays, Breast, Monte Carlo methods, Signal attenuation, X-ray imaging

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Proceedings Article | 19 March 2014 Paper

Optimization using detective quantum efficiency (DQE) of the high-resolution parallel-hole collimators with CdTe pixelated semiconductor SPECT system

Young-Jin Lee, Dae-Hong Kim, Ye-seul Kim, Hee-Joung Kim

Proceedings Volume 9033, 90334J (2014) https://doi.org/10.1117/12.2043006

KEYWORDS: Collimators, Semiconductors, Single photon emission computed tomography, Spatial resolution, Modulation transfer functions, Sensors, Gamma radiation, Monte Carlo methods, Silicon, Point spread functions

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Proceedings Article | 6 March 2013 Paper

Comparison of photon counting and conventional scintillation detectors in pinhole SPECT system for small animal imaging

Young-Jin Lee, Hyun-Ju Ryu, Su-Jin Park, Hee-Joung Kim

Proceedings Volume 8668, 866845 (2013) https://doi.org/10.1117/12.2005897

KEYWORDS: Sensors, Photon counting, Spatial resolution, Collimators, Scintillation, Single photon emission computed tomography, Imaging systems, Monte Carlo methods, Preclinical imaging, Image resolution

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Proceedings Article | 9 March 2012 Paper

The effect of energy weighting on x-ray imaging based on photon counting detector: a Monte Carlo simulation

Seung-Wan Lee, Yu-Na Choi, Hyo-Min Cho, Young-Jin Lee, Hyun-Ju Ryu, Hee-Joung Kim

Proceedings Volume 8313, 83135M (2012) https://doi.org/10.1117/12.910845

KEYWORDS: Sensors, Photon counting, Monte Carlo methods, X-ray imaging, X-ray detectors, Blood, Iodine, Gadolinium, X-rays, Image quality

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Photon counting detector based on semiconductor materials is a promising imaging modality and provides many benefits for x-ray imaging compared with conventional detectors. This detector is able to measure the x-ray photon energy deposited by each event and provide the x-ray spectrum formed by detected photon. Recently, photon counting detectors have been developed for x-ray imaging. However, there has not been done many works for developing the novel x-ray imaging techniques and evaluating the image quality in x-ray system based on photon counting detectors. In this study, we simulated computed tomography (CT) images using projection-based and image-based energy weighting techniques and evaluate the effect of energy weighting in CT images. We designed the x-ray CT system equipped with cadmium telluride (CdTe) detector operating in the photon counting mode using Geant4 Application for Tomographic Emission (GATE) simulation. A micro focus X-ray source was modeled to reduce the flux of photons and minimize the spectral distortion. The phantom had a cylindrical shape of 30 mm diameter and consisted of ploymethylmethacrylate (PMMA) which includes the blood (1.06 g/cm³), iodine, and gadolinium (50 mg/cm³). The reconstructed images of phantom were acquired with projection-based and image-based energy weighting techniques. To evaluate the image quality, the contrast-to-noise ratio (CNR) is calculated as a function of the number of energy-bins. The CNR of both images acquired with energy weighting techniques were improved compared with those of integrating and counting images and increased as a function of the number of energy-bins. When the number of energy-bins was increased, the CNR in the image-based energy weighting image is higher than the projection-based energy weighting image. The results of this study show that the energy weighting techniques based on the photon counting detector can improve the image quality and the number of energy-bins used for generating the image is important.

Proceedings Article | 9 March 2012 Paper

Optimization of hardware-based photon rejecter to separate electronic noise in the photon counting detector

Hyo-Min Cho, Hee-Joung Kim, Yu-Na Choi, Seung-Wan Lee, Young-Jin Lee, Hyun-Ju Ryu

Proceedings Volume 8313, 83135Z (2012) https://doi.org/10.1117/12.910793

KEYWORDS: Aluminum, Sensors, Iodine, Image quality, Photon counting, Interference (communication), X-ray imaging, Cadmium, Photodetectors, Image acquisition

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Proceedings Article | 3 March 2012 Paper

Optimization of high resolution collimator with CdTe detector: a simulation study

Young-Jin Lee, Hee-Joung Kim, Hyun-Ju Ryu, Hyo-Min Cho, Seung-Wan Lee, Yu-Na Choi

Proceedings Volume 8313, 831365 (2012) https://doi.org/10.1117/12.910846

KEYWORDS: Collimators, Sensors, Spatial resolution, Image resolution, Imaging systems, Monte Carlo methods, Cameras, Photon counting, Cadmium, Semiconductor materials

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Proceedings Article | 3 March 2012 Paper

Development of a pinhole collimator SPECT-CT system using a CdTe detector sample

Hyun-Ju Ryu, Young-Jin Lee, Seung-Wan Lee, Hyo-Min Cho, Yu-Na Choi, Hee-Joung Kim

Proceedings Volume 8313, 831364 (2012) https://doi.org/10.1117/12.910902

KEYWORDS: Sensors, Single photon emission computed tomography, Collimators, Point spread functions, X-rays, X-ray computed tomography, Imaging systems, Spatial resolution, Modulation transfer functions, X-ray imaging

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Showing 5 of 15 publications

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