• Journal of radiological science and technology
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• v.26 no.1
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• pp.31-37
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• 2003

The conclusions after appraisal usefulness of korean 30 kHz inverter type X-ray equipments which are currently used in the clinics are like those followings. 1. The specific characters of mA, kVp, msec in the radiography keep very good accuracy and showed good waveform also under KS regulations. 2. The output of the X-ray equipment is showed 1.7 times higher than single-phase. 3. mA, kVp of the fluoroscopy and Sopt film exposure mA, kVp showed appropriated results under the regulations. 4. As we consider the conversion factor of image intensifier tube used for two years, it showed pretty high results, 310 at 75 kV, and knew that the conversion factor which followed by increasing kVp increased its computations like Kim's experimentation. Those X-ray equipment showed excellent results in the appraisal while those were operating so we think that those X-ray equipments will be substitute for expensive foreign equipment in korean domestic medical equipment in the future.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.353-360
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• 2020

This research aims at suggesting exposure condition that shows maintaining the value of the physical image quality factor by decreasing tube voltage and tube current from the standard exposure condition(80 kV, 7 mA) of a CBCT apparatus. To measure the value of the physical image quality factor, modular transfer function(MTF) was analyzed and dose-area product(DAP) was used for the measurement of exposure dose. CBCT images of a Sedentex IQ phantom were obtained under 15 exposure conditions of different combination of tube voltage(80, 78, 76 kV) and tube current(7, 6, 5, 4, 3 mA) and MTF 10 was calculated under each exposure conditions. There were no significant differences in MTF 10 under 80 kV-6 mA, 80 kV-5 mA exposure conditions in comparison with standard exposure condition. Based on the results of this research, 80 kV-5 mA condition are expected to be able to reduce exposure dose with maintaining the value of the physical image quality factor of the standard exposure condition.

• Progress in Medical Physics
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• v.26 no.1
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• pp.28-35
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• 2015

In this study, we investigated the effects of an iterative reconstruction algorithm and an automatic exposure control (AEC) technique on image quality and radiation dose through phantom experiments with coronary computed tomography (CT) angiography protocols. We scanned the AAPM CT performance phantom using 320 multi-detector-row CT. At the tube voltages of 80, 100, and 120 kVp, the scanning was repeated with two settings of the AEC technique, i.e., with the target standard deviations (SD) values of 33 (the higher tube current) and 44 (the lower tube current). The scanned projection data were reconstructed also in two ways, with the filtered back projection (FBP) and with the iterative reconstruction technique (AIDR-3D). The image quality was evaluated quantitatively with the noise standard deviation, modulation transfer function, and the contrast to noise ratio (CNR). More specifically, we analyzed the influences of selection of a tube voltage and a reconstruction algorithm on tube current modulation and consequently on radiation dose. Reduction of image noise by the iterative reconstruction algorithm compared with the FBP was revealed eminently, especially with the lower tube current protocols, i.e., it was decreased by 46% and 38%, when the AEC was established with the lower dose (the target SD=44) and the higher dose (the target SD=33), respectively. As a side effect of iterative reconstruction, the spatial resolution was decreased by a degree that could not mar the remarkable gains in terms of noise reduction. Consequently, if coronary CT angiogprahy is scanned and reconstructed using both the automatic exposure control and iterative reconstruction techniques, it is anticipated that, in comparison with a conventional acquisition method, image noise can be reduced significantly with slight decrease in spatial resolution, implying clinical advantages of radiation dose reduction, still being faithful to the ALARA principle.

• Progress in Medical Physics
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• v.18 no.3
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• pp.139-143
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• 2007

The purpose of this study was to measure and evaluate radiation dose for MDCT parameters. Patient dose for various combination of MDCT parameters were experimentally measured, using MDCT (GE light speed plus 4 slice, USA), model 2026C electrometer (RADICAL 2026C, USA), standard Polymethylmethacrylate (PMMA) head and body CT dosimetry phantoms. In clinical situations, for a typical abdominal scan performed with MDCT at 120 kVp, 180 mAs, 20 mm collimation, and a pitch of 0.75 $CTDI_w,\;CTDI_{vol}$ were measured as 20.2 mGy, 26.9 mGy, respectively. When scan length is assumed as 271.3 mm, DLP and measured effective dose of the abdominal would be calculated as $729.1\;mGy{\cdot}cm$, 10.9 mSv, respectively.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.264-272
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• 2011

This study was function experiment or inspection of diagnosis x-ray unit at the hospital. It's how many changes tube voltage, tube current, DOSE value through the experiment depending on temperature increasing. The study want to know whether which parameter shown out of range or not how about image quality and so on. Increasing tube current and DOSE were not only too many radiation to the patient and radiation workers and make bad images but also the tube should be damaged by heat. This study was recommended proper exposure at intervals of seconds because passed inspection, reduced radiations for patient and the tube used long term. This results in the hospital`s finances will be very helpful.

• The Journal of the Korea Contents Association
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• v.9 no.3
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• pp.225-231
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• 2009

The purpose of the current study was to compare radiation dose of 64MDCT performed with automatic exposure control (AEC) with manual selection fixed tube current. We evaluated the CT scans of phantom of the chest and abdomen using the fixed tube current and AEC technique. Objective image noise shown as the standard deviation of CT value in Hounsfield units was measured on the obtained images. Compared with fixed tube current, AEC resulted in reduction of the chest and abdomen in the CTDIvol (35.2%, 5.9%) and DLP (49.3%, 3.2%). Compared with manually selected fixed tube current, AEC resulted in reduced radiation dose at MDCT study of chest and abdomen.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.192-198
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• 2003

Recently, the Inverter type X-ray generator is rapidly replacing the conventional single-phase or three-phase X-ray generator, it has several merits of space-saving: high accuracy and reproducibility. This paper presents a 40kw(12kV, 80mA) high tension generator system for diagnosis X-ray. The control circuit and design consideration of the proposed high tension power supply are given. Issues in the design of high voltage isolating transformer are discussed. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. 1'he proposed apparatus has several advantages, e. g., the fast rising time of tube voltage, accuracy and reduced component size etc.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.185-187
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• 2007

기존 LCD 백라이트 인버터 시스템은 램프 관전류 제어를 위해 인버터 구동 펄스 폭의 크기를 변조하는 PWM(Pulse Width Modulation) 방식이다. 이 경우 시비율의 폭을 가변함에 따라 효율 저감 및 회로 발열 등의 단점이 있다. 본 논문에서는 인버터를 고정 주파수 및 50% 고정 시비율로 구동하고 램프 관전류 제어를 위해 링크전압을 제어하는 새로운 방식을 제안한다. 이를 통해 효율 증대, EMI 성능의 향상 및 전체 시스템의 원가저감 효과를 획득 할 수 있다.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.887-893
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• 2018

The purpose of this study is to compare the performance of X-ray generators installed in hospitals and universities and apply the quality control items of diagnostic X-ray generators to recognize the importance of periodic performance management. First, the reproducibility and linearity test results showed that the PAE of the reproducibility evaluation was high for the GX-650 devices that met the acceptance criteria in all the experimental conditions and lacked the periodic quality control. In the linearity evaluation, when the tube voltage was set to 100 kVp, It was measured to deviate from the error. In addition, it was found that the PAE in the low-accuracy evaluation results relative to an X-ray tube voltage and tube current of the device low occurrence frequency. The HVL experiment was included in all of the devices at the HVL by tube voltage. Therefore, it is necessary to recognize the importance of quality control of all devices rather than hospital and laboratory, and to manage the device performance by actively managing the device, and to establish a short - term quality control system like special medical devices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8479-8486
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• 2015

This study aim is occur in brain CT cause of beam hardening effect and reducing method, We will scan Bone opaque bead phantom on variation of image on the influence factor with equipment called 'Samatom Senation 16' with following listed herein : tube voltage, tube current, slice thickness, gantry angle, base line which affect beam-hardening effect. After that we are going to start Quantitative Analysis resulted in previous scanning and Qualitative Assessment with CT image sheet evaluation. result of quantitative analysis 140kVp $31.56{\pm}2.89HU$ on tube voltage, 150mA $-3.87{\pm}0.12HU$ on tube current, 3mm on slice thickness, and $13.31{\pm}1.03HU$ IOML on gantry angle which was the least beam-hardening effect. Like Qualitative Analysis, we went through Qualitative Assessment and most of valuers got a result of 140kVp on tube voltage, 150mA on tube current, 3mm on slice thickness. As before valuers evaluated gantry angle that scanned image from IOML or OML was the least beam-hardening effect occured. There are meaningful differences when we compare all theses factors statistically(P<0.05). therefore We consider that Minimizing artifact that caused by beam-hardening effect can provide better quality of image to deciphers and patients. if we rise tube voltage in permissible dose limit, set tube current in a limit that does not effect to image quality, use slice thickness too thin enough to harm resolution, use IOML or OML on gantry angle.