• Progress in Medical Physics
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• v.19 no.4
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• pp.209-218
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• 2008

According to improved radiation therapy technology such as IMRT and proton therapy, the accuracy of patient alignment system is more emphasized and IGRT is dominated research field in radiation oncology. We proposed to study the feasibility of cone-beam CT system using simple x-ray imaging systems for image guided proton therapy at National Cancer Center. 180 projection views ($2,304{\times}3,200$, 14 bit with 127 ${\mu}m$ pixel pitch) for the geometrical calibration phantom and humanoid phantoms (skull, abdomen) were acquired with $2^{\circ}$ step angle using x-ray imaging system of proton therapy gantry room ($360^{\circ}$ for 1 rotation). The geometrical calibration was performed for misalignments between the x-ray source and the flat-panel detector, such as distances and slanted angle using available algorithm. With the geometrically calibrated projection view, Feldkamp cone-beam algorithm using Ram-Lak filter was implemented for CBCT reconstruction images for skull and abdomen phantom. The distance from x-ray source to the gantry isocenter, the distance from the flat panel to the isocenter were calculated as 1,517.5 mm, 591.12 mm and the rotated angle of flat panel detector around x-ray beam axis was considered as $0.25^{\circ}$. It was observed that the blurring artifacts, originated from the rotation of the detector, in the reconstructed toomographs were significantly reduced after the geometrical calibration. The demonstrated CBCT images for the skull and abdomen phantoms are very promising. We performed the geometrical calibration of the large gantry rotation system with simple x-ray imaging devices for CBCT reconstruction. The CBCT system for proton therapy will be used as a main patient alignment system for image guided proton therapy.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.370-374
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• 2009

In this paper, we presents a new cone beam computerized tomography (CB CT) system for the reconstruction of 3 dimensional dynamic images. The system using cone beam has less the exposure of radioactivity than fan beam, relatively. In the system, the reconstruction 3-D image is reconstructed with the radiation angle of X-ray in the image processing unit and transmitted to the monitor. And in the image processing unit, the Three Pass Shear Matrices, a kind of Rotation-based method, is applied to reconstruct 3D image because it has less transcendental functions than the one-pass shear matrix to decrease a time of calculations for the reconstruction 3-D image in the processor. The new system is able to get 3~5 3-D images a second, reconstruct the 3-D dynamic images in real time.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.468-470
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• 2002

We have designed X-ray detection system and multi-channel data acquisition system for Spiral CT application. X-ray detection system consists of scintillator and photodiode. Scintillator converts X-ray into visible light. Photodiode converts visible light into electrical signal. The multi-channel data acquisition system consists of analog, digital, master and backplane board. Analog board detects electrical signal and amplifies signal by 140dB. Digital board consists of MUX(Multiplex) which routes multi-channel analog signal to preamplifier, and ADC(Analog to Digital Converter) which converts analog signal into digital signal. Master board supplies the synchronized clock and transmits the digital data to image reconstructor. Backplane provides electrical power, analog output and clock signal. The system converts the projected X-ray signal over the detector array with large gain, samples the data in each channel sequentially, and the sampled data are transmitted to host computer in a given time frame. To meet the timing limitation, this system is very flexible since it is implemented by FPGA(Field Programmable Gate Array). This system must have a high-speed operation with low noise and high SNR(signal to noise ratio), wide dynamic range to get a high resolution image.

• Progress in Medical Physics
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• v.13 no.4
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• pp.229-233
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• 2002

We have tested a combined CT/SPECT system with a single CZT detector for x-ray and gamma-ray medical imaging. The size of detector is 10$\times$10$\times$5 ㎣, and the anodes are pixellated as a 4$\times$4 array with a pixel dimension of $1.5\times$1.5 $\textrm{mm}^2$. The cathode was coated with a continuous Au-plated. We have characterized the system performance by scanning a radiographic resolution phantom and the Hoffman Brain phantom. Pulse counting electronics with very short shaping time (50 ㎱) are used to satisfy high photon rates in x-ray imaging, and response linearity up to 3$\times$10$^{5}$ counts per second per detector element is achieved. Energy resolution of 10.4% and 5.3% FWHM at Tc-99m 140 keV peak are obtained for the 50 ㎱ and 2 $mutextrm{s}$ shaping times, respectively. The spatial resolutions of CT and SPECT are about 1mm and 9mm, respectively. Photopeak efficiency of detector systems are 41.0% for 50㎱ and 72.5% for 2 $mutextrm{s}$ shaping time.

• Journal of radiological science and technology
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• v.20 no.1
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• pp.15-20
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• 1997

Unlike conventional CT scan, the helical CT scan uses continuous rotating CT equipment with a slip ring to move the patient's coach at a constant speed while continuously scanning. Slice sensitivity profiles in the Z-position(SSPz) using the conventional X-ray CT have a shape similiar to a rectangular wave, which slightly spreads out into plains below the mountain. However, in the helical CT, with an expansion of the base, the rectangular shape collapses and a mouatain-like shape can be seen. We need to investigate the fellowing factors in helical CT scanning;the ability to scan along the axis of the body, effective slice width, slice shape and the precision of coach velocity, Helical scanning with sprial X-ray track is different from the conventional scanning in terms of the principle of image reconstruction performed. We believe that the problems in helical scanning can be solved by understanding new the special parameters such as the bed moving speed and the interval of image reconstruction.

• Proceedings of the Korea Multimedia Society Conference
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• 1998.10a
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• pp.321-326
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• 1998

본 연구에서는 환자와 한의사, 방사선 전문의 간에 초고속 통신망을 이용하여 원격으로 환자의 질환 상태를 파악하고 이에 따른 처방전을 내릴 수 있도록 하는 한방 원격 검진 시스템에서 환자의 X-ray 사진, CT 사진 등의 방사선 이미지들을 DICOM 프로토콜에 의거하여 저장하고 검색할 수 있도록 해주는 시스템을 구현하였다. 본 연구에서는 이미지 처리 및 관리 모듈을 Java 언어를 이용하여 구현함으로써 방사선 전문의와 한의사들이 컴퓨터의 기종에 관계없이 웹브러우저를 사용하여 환자의 X-ray나 CT 등의 방사선 사진을 살펴볼 수 있도록 하였다.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.741-745
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• 1991

This paper describes a feature extraction in digitized chest X-ray image and CT head Image. There are Extraction, Thresholding, Region G rowing, Split-Merge and Relaxation in feature extraction technique. In this study, Region Growing System was realized and Fuzzy Set Theory was applied in order to extract the vague region which the conventional method has difficulties in extracting. The performance of proposed algorithm was proved by being applied to chest X-ray image and CT head image.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.13-16
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• 2002

Recent topics on quality assurance (QA) of X-ray diagnosis in Japan were reported in this presentation. These were related to mass screening mammography (MMG), lung screening CT (LSCT), skin injury caused by interventional radiology (IVR) and traceable system of dosimeters for x-ray diagnosis. In these successful stories, the author would like to stress the cooperation of all the medical am: clinical staff including medical doctors, radiological technologists, medical physicists, manufacturers of medical devices and others.

• International Journal of Contents
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• v.4 no.1
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• pp.12-15
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• 2008

In this paper, we propose a new method of background removing for digital self-adaptive acquisition in medical X-ray imaging. We analysis the construction of video digital acquisition system and main factors of acquired image quality, propose a more efficiency method to against background non-uniformly. With proposed method, non-uniform illumination back ground was well removed without image quality degradation.

• Korean Journal of Acupuncture
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• v.19 no.2
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• pp.1-12
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• 2002

Objectives : Assuming That the Characteristic of Meridian System Has Been Similar to This of Electric Potentials in Human Body and That Measurements of Electric Potential at Well and Sea Points in Branches of the Twelve Meridians Will Be Representative of Measurements of the Twelve Meridians, to Measure the Electric Potentials in Healthy Volunteers(HG), Patients Diagnosed As a Cerebral Infarction(CG), a Arrhythmia(AG), a Other Intervertebral Disc Disorder(IG), and a Joint Disorder(JG), and Then to Find Out the Characteristic of Biophysical Meridian System, Finally to Compare with the Results of the Electric Potential in Those Groups. Methods : We Selected Who HG Were Diagnosed by a Blood Test, Urine Examination and Differentiation of Syndromes by Five Viscera among Volunteers, CG by CT and Wind-Syndrome Caused by Hyperactivity of the Liver-Yang, AG by EKG, CT, and Deficiency or the Heart Blood, IG by X-ray or CT and Pain in Waist, and JG by X-ray and Knee Pain. Their Electric Potential of Well and Sea Points in the Meridians Were Measured by hysiograph. Results and Conclusions : Measurements Were Analyzed by Factor Analysis, Analysis of Variance, and Logistic Regression Model, We Obtained That Most of the Results, In Conclusion, Hold Good for the Classical Meridian Doctrine.