• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.663-669
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• 2017

In diagnostic medical imaging, it is essential to reduce the scattered radiation for the high medical image quality and low patient dose. Therefore, in this study, the influence of the scattered radiation on medical images was analyzed as the tube voltage increases. For this purpose, ANSI chest phantom was used to measure the scattering ratio, and the scattering effect on the image quality was investigated by RMS evaluation, RSD and NPS analysis. It was found that the scattering ratio with increasing x-ray tube voltage gradually increased to 48.8% at 73 kV tube voltage and to 80.1% at 93 kV tube voltage. As a result of RMS analysis for evaluating the image quality, RMS value according to increase of tube voltage was increased, resulting in low image quality. Also, the NPS value at 2.5 lp/mm spatial frequency was increased by 20% when the tube voltage was increased by 93 kV compared to the tube voltage of 73 kV. From this study, it can be seen that the scattering radiation have a significant effect on the image quality according to the increase of x-ray tube voltage. The results of this study can be used as basic data for the improvement of medical imaging quality.

• Journal of the Korean Society of Radiology
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• v.11 no.2
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• pp.79-85
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• 2017

The purpose of this study is to investigate the cause analysis according to the difference between the pre exposure tube voltage and actual exposure tube voltage in mammography in connection with breast pressure thickness, breast size and body mass index and to find the improvement. The study tracked 377 women age 40 and older among the mammography examiners conducted by the National Health Insurance Corporation. It was analyzed that breast pressure thickness, breast size and body mass index according to the difference between the pre exposure tube voltage and actual exposure tube voltage among the parameters of dose report been sent to the picture archiving communication system with reference to the image with cranio-caudal projection in mammography. As are result, it shows that the thicker the breast thickness, smaller the breast size and lower body mass index, the higher the difference of tube voltage. In conclusion, the minimum tube voltage of mammography machine should be reset in order to set the tube voltage according to breast pressure thickness and breast size that are suitable for our country in mammography, in addition, it was considered that radiologist should make an effort to reduce radiation exposure and make a good quality image with reducing the difference of mammography condition by making a correct exposure condition in case of examining the patients with thin breast pressure and small breast size.

• Journal of the Korean Society of Radiology
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• v.12 no.4
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• pp.541-547
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• 2018

To evaluate the effect of dose and image quality for Chest Digital Tomosynthesis(CDT) using sensitivity and tube voltage(kV). CDT images of the phantom were acquired varying sensitivity 200, 320, 400 according to set tube voltage of 125 kV and 135 kV. The dose and Dose Area Product(DAP) according to change of sensitivity and kV were evaluated and Image quality was evaluated by PSNR, CNR, SNR using Image J. Dose were lowered 14~23% less than sensitivity 200, 125 kV and DAP were lowered 13~26% less than sensitivity 200, 125 kV. PSNR were over 27 dB, which were significant value and CNR, SNR were better as sensitivity value was lower. But there were different statistical significant to each item. CNR and SNR were not statistically significant at sensitivity 320, 135 kV(P>0.05). CDT can improve image quality with lower radiation dose using better than quality and correction power at digital radiography system.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.185-191
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• 2018

The purpose of this study was to evaluate the usefulness of BMI application to Urography CT by applying different tube voltages in accordance with body mass index. Group A (n = 38) with body mass index of lower than 25 was examined with tube voltage of 100 kVp while Group B (n = 45) with a BMI of 25 and higher was examined with tube voltage of 120 kVp. C group (n = 37) with body mass index (BMI) of lower than 25 was examined with tube voltage of 120kVp. Although the difference in average dose between group A (100 kVp) and group C (120 kVp) with low body mass index (BMI) of lower than 25 was $214.8mGy{\cdot}cm$, there was no significant difference in qualitative evaluation and, compared with patient group with body mass index of 25 and higher, results obtained were rather good. Therefore, this study verified that the tube voltage of lower than 100 kVp does not have adverse effect on the quality of image for patients with body mass index (BMI) of lower than 25.

• The Journal of the Korea Contents Association
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• v.19 no.12
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• pp.517-526
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• 2019

The purpose of this study is to find the optimal method for clinical application by analyzing image quality and radiation output according to parameter combination when using the Automatic Exposure Control (AEC). The experimental method combines 70, 81 kVp with sensitivity S200, S400, S800 and S1000 of the Automatic Exposure Control for Entrance Surface Dose (ESD), current volume, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR), Time-to-Radiation Dose Curve in abdomen and pelvis. And then, image quality and radiation output stability were evaluated. As a results, Entrance Surface Dose, current volume, Signal to Noise Ratio, Contrast to Noise Ratio decreased as the tube voltage and sensitivity were set higher. In addition, the higher tube voltage and sensitivity, the Time-to-Radiation Dose Curve showed a poor output stability. In conclusion, the higher the combination of tube voltage and sensitivity in the use of Automatic Exposure Control, the more problems can be seen in image quality and stability of the radiation output. Therefore, a relatively low combination of tube voltage and sensitivity showed that the image quality and radiation output stability could be optimized by minimizing the error range that would occur when the detector recognized a combination of parameters.

• Progress in Medical Physics
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• v.17 no.4
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• pp.201-206
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• 2006

In this study, we have fabricated the noninvasive tube voltage meter which can observe the waveform of tube voltage and measure the tube voltage by using the Intensity of X-ray beam irradiated from radiotherapy simulator and also investigated the feasibility for clinical applications. Two pin photodiodes acting as X-ray detectors were arranged in parallel at the position of ${\pm}1.4cm$ in the y-axis of X-ray field and the aluminum filters with different thickness were placed above them. Using this detector, we could get the ratio ($r_{eff}$) of the relative output voltage which is proportional to the thickness of the filters. And the logarithm of effective peak tube voltage ($InkV_{p,eff}$) was obtained by Victoreen's NERO 6000M used as reference tube voltage meter. From the linear regression analysis of $r_{eff}$ and In $kV_{p,eff}$ the correlation coefficient (r) of linear equation was obtained to be 0.996 for the calibration of the tube voltage meter. Therefore, we suggest that the noninvasive tube voltage meter fabricated in this study can be used for clinical applications due to Its high accuracy.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.749-755
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• 2019

In this study, we investigated the effects of tube voltage (kVp) and tube current (mAs) on an exposure index (EI) applied to a digital radiography. There used an inverter type digital X-ray generator and an image receptor (IR) utilized a portable wireless detector without a grid. Radiographic images were acquired using a cone pyramid phantom produced using a 3D printer. The X-ray tube voltage was increased from 40 kVp to 120 kVp with 10 kVp increment, and the tube current was increased from 1 mAs to 128 mAs with the twice increment. As a result, kVp had logarithmic relationship with the EI as high $R^2$ value, and mAs had a very high linear relationship too. Also, there was a high correlation between the area dose and the EI of the IR, with the $R^2$ value being 0.76 or more. In conclusion, it had showed that mAs affected the EI linearly, and that it could be advantageous to adjust the easy-to-predict mAs to maintain proper image qualities.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.430-434
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• 2004

본 논문에서는 관전류 직접제어 방식을 채택한 3.2kW(80kV,40mA)급 최소형, 최경량 Portable X-선 장치를 제안한다 본 장치는 X-선 발생을 위한 고전압 발생 단에 모노탱크 블록 사용하였고, 고주파 고전압용 인버터에는 스위칭 전력소자로서 Mini block type의 MOS-FET를 채용, 80kHz로 스위칭 함으로서 고전압 변압기를 비롯한 고전압 발생부의 크기와 무게를 최소화하였다. X-ray Power의 출력이 높아짐에 따라, X-ray tube의 필라멘트 인버터의 출력용량 또한 증가되었다. 본 논문에서는 설정 관전류에 대한 정밀한 제어를 위하여 2단계 모드로 필라멘트 예열을 행하여 관전류 응답특성을 개선하였으며 제안한 휴대용 X-선 발생장치의 부하변동에 따른 X-선 관전압과 관전류의 개선된 특징을 실험파형을 통하여 입증하였다.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.750-754
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• 2003

본 논문에서는 X-선 관전류를 직접 검출하여 제어하는 2.4kW(80kv,30mA)급 최소형, 최경량 휴대용 X-선 발생 장치를 제안한다. 본 장치는 X-선발생을 위한 고전압 발생단에 모노탱크 블록 사용하였고, 고주파 고전압용 인버터에는 스위칭 전력소자로서 MOS-FET를 채용, 70kHz로 스위칭 함으로서 고전압 변압기를 비롯한 고전압 발생부의 크기와 무게를 최소화하였다. 또한, 설정 관전류에 대한 정밀한 제어를 위하여 2단계 모드로 필라멘트 예열을 행하여 관전류 응답특성을 개선하였으며 제안한 휴대용 X-선 발생장치의 부하변동에 따른 X-선 관전압과 관전류의 개선된 특징을 실험파형을 통하여 입증하였다.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.373-379
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• 2018

The purpose of this study was to investigate quantitative data on the difference in breast entrance surface dose with changes in focus-film distance, patient posture (anteroposterior-posteroanterior), thoracic wall thickness, rib bone thickness, lung tissue thickness, tube voltage, and high-voltage rectification method in Whole Spine Scanography, which is necessary for the treatment of scoliosis patients. Given a tube voltage of 90 kVp, kerma of 0.1 mGy, focus-film distance of 260 cm, tube voltage ripple rate of 0, filter thickness of 3.5 mm, and thickness of patient's thoracic wall of 120 mm as an X-ray exposure condition, from the simulation results using the Simulation of X-ray Spectra program to confirm the reduction effect of breast entrance surface dose according to the patient's posture (AP and PA), there was a dose reduction effect in aluminum filter thickness of 2.6 times at 3.5 mm, 25.7 times the thoracic wall thickness at 120 mm, 1.43 times higher tube voltage, and 0 to 1.14 times the tube voltage ripple rate. The total dose reduction effect was about 109 times. In order to confirm the dose reduction effect of RANDO phantom posture (AP and PA), from the results of the measurements taken under the conditions that the focus-film distance was 260 cm, the tube voltage was 90 kVp, the tube current was 270 mA, the exposure time was 0.31 sec, and the tube voltage ripple rate of X-ray generators was 0, the entrance surface dose reduction effect of the breast in the PA position was found to be 20.56 times lower than that of the AP position.