간행물
Journal of the Korean Society of Radiology KCI 등재 한국방사선학회논문지 Journal of the Korean Society of Radiology (JKSR)
- 발행기관 한국방사선학회
- 자료유형 학술지
- 간기 연7회
- ISSN 1976-0620 (Print)
- 수록기간 2007 ~ 2019
- 주제분류 공학 > 원자력공학 공학 분류의 다른 간행물
- 십진분류KDC 512DDC 610
권호리스트/논문검색
Volume 11 Number 3 (2017년 6월) 10건
1.
2017.06
서비스 종료(열람 제한)
DC/DC switching power converters are commonly used to generate a regulated DC output voltage with high efficiency. The advanced DC/DC converter uses a PWM-IC with OP-Amp. (Operational Amplifier) to control a MOSFET (metal-oxide semiconductor field effect transistor), which is a switching component, efficiently. In this paper, it is shown that the electrical characteristics of OP-Amp. are affected by radiations of γ rays using 60Co for TID (Total Ionizing Dose) testing and 5 heavy ions for SEL (Single Event Latch-up) testing. TID testing on OP-Amp. is accomplished up to the total dose of 30 krad, and the cross section(㎠) versus LET(MeV/mg/㎠ ) in the OP-Amp. operation is evaluated SEL testing after implementation of the controller board.
2.
2017.06
서비스 종료(열람 제한)
The purpose of this study was to evaluate the clinical efficacy of 128 MDCT (multi-detector computed tomography) for reducing the CareDose 4D dose and comparing the image quality with the fixed tube current technique. For this purpose, we conducted the phantom and clinical studies to evaluate the exposure dose and image of the subject before and after applying the CareDose 4D system in abdominal examination using 128 MDCT. In the phantom study, ROI (Region of interest) was located at the center, 3, 6, 9, 12 o'clock, into two groups: group A without CareDose 4D and Group B applied were measured. In the clinical study, ROI was located at the liver 8 segments, divided into two groups too. The measured items were CT number, noise, and dose length product (DLP) dose. The result of CTDIvol (CT Dose Index volume) measurements in phantom and clinical studies were lower than those before CareDose 4D application, and dose and effective dose were also measured lower (p<.05). There was no difference in CT number before and after application (p>.05). In conclusion, using CareDose 4D, we can obtain optimal image information without deteriorating image quality while reducing patient dose.
3.
2017.06
서비스 종료(열람 제한)
With the increase in leisure life, the population of ski resorts is rapidly increasing. The activity at the ski resort is likely to receive a direct chance of natural sunlight or space ray. Because it is located in the mountains where altitude exists. As a general rule, it is widely known that the higher the elevation rate, the more increasing the natural radiation dose. However, the natural radiation dose rate for the ski slopes has not been reported yet. Various ski resorts exist in Korea, but this study had chose 4 ski resorts to measure the natural dose of natural radiation. As a result, the natural radiation dose for the ski slope was measured at a relatively high dose of ordinary living areas. However, the level of natural radiation dose was not worrisome. It is recommended to wear ski wear or goggles to minimize natural radiation exposure at the ski slopes
4.
2017.06
서비스 종료(열람 제한)
Compton suppression apparatus using the Compton scattering response, by inhibiting part of the spectrum Compton continuum Compton continuum in the area of the peak analysis of the gamma rays that enables a clearer device. In order to find out the geometry structure of high-purity germanium detector(HPGe) -NaI(TI) and to optimize the effect of movement, Monte Carlo simulation was used to grasp the behavioral characteristics of Compton suppression and compare several layout structures. And applied to the cylinder beaker used for the environmental measurement by using the efficiency according to the distance. For the low-energy source such as 81 keV, the Compton continuum is scarcely developed and the suppression effect is also insignificant because the scattering cross-section of the Compton effect is relatively low. In the spectrum for the remaining energy, it can be seen that the Compton continuum part is suppressed in a certain energy range. Compton suppression effect was not significantly different from positional shift. average reduction factor(ARF) value was about 1.08 for 81 keV and about 1.23 for 1332.4keV energy at the highest value .It can be seen that suppression over the Compton continuum region of the energy spectrum is a more appropriate arrangement. Therefore, it can be applied to various environmental sample measurement through optimized structure.
5.
2017.06
서비스 종료(열람 제한)
This study investigated the risk factor of Gallbladder stone in Busan and Kyungnam area. The subjects of the experiment was performed with patients by abdominal ultrasonography among the patients who came to the P hospital from June 2016 to December 2016. Among them, risk factors were analyzed on 353 people at the same time when abdominal ultrasonography and hematological test. The statistical analysis of risk factors related to the Gallbladder stone was performed by independent t-test and chi-square test. In consider of difference verification result for calculations odds ratio about independent variables, multiple logistic regression analysis to conduct verify adequacy by calculating forecasting model from variable. As a result, Gallbladder stone risk factors have relevance to age ɤGTP with probability model and values to calculated. Age was showed sensitivity 49.7%, specificity 82.2%, receiver operating characteristic area under curve 0.724. Forecasting probability sensitivity 69.3%, specificity 62.4%, receiver operating characteristic area under curve 0.699 showed, ɤGTP confirmed validity of forecasting model
6.
2017.06
서비스 종료(열람 제한)
At the Brain MRI examination, RF Pulse are irradiated on the human head in order to acquire MR images. At this time, a considerable part of the irradiated RF Pulse energy is absorbed in our body and the temperature of the human head will rise depending on the degree of exposure, so it will affect the human head. Even if the same RF Pulse energy is given, if the metal is inserted in the human head, the conductivity of the human head is greatly increased by the metal, so the SAR value increases and the temperature also rises. Therefore, we started this research with the question as to whether there is difference between the change in SAR value and temperature displayed on the head of the human according to use or not of the dental implant. Experiments were using the XFDTD program on a 128 MHz RF Pulse frequency by a 3.0 tesla MRI. We can see that both are increasing that the average value of SAR and temperature that absorbed by the human head model used the dental implant. In addition, the average maximum SAR value and the maximum temperature rise in the brain part are shown below the international safety standard value but the influence can not be ignored because of the result may change according to the increase in the number of dental implant. And as future tasks. we need to the simulation of temperature rise and SAR due to an increase in the number of implants and volumes of teeth, dental implant material.
7.
2017.06
서비스 종료(열람 제한)
Potentially lethal damage repair (PLDR) in HFL-I was investigated by delayed plating experiments. The surviving fraction data were fitted to the linear Quadratic equation (LogSn=-nγ(αd+βd2) where γ=1 for immediate plating). And a repair factor γ was developed to compare survival for immediate and delayed plating . When we only took into account the repair factor of PLDR γ which was derived from the delay assay, the cell survival response th fractionated carbon ion irradiation was not fully matched. This gap suggested that consideration of another repair process is necessary. So this suggests that the various repair process plays an important role in the fractionated irradiations.
8.
2017.06
서비스 종료(열람 제한)
Chronic kidney disease can be treated if it is detected early, but as the disease progresses, it becomes impossible to recover. Finally, renal replacement therapy such as transplantation or dialysis should be used. Ultrasonography is used to diagnose kidney cancer, inflammatory disease, nodular disease, and chronic kidney disease. It is used to identify information about degree of inflammation using information such as kidney size, internal echo characteristics. Currently, the degree of disease in the clinic uses the value of glomerular filtration rate. However, even in ultrasound, changes in the degree of inflammation and disease can be observed. In this study, we used ultrasound images to quantify the changes in brightness, size, cortex, and subclinical changes of the kidney with progression of the disease, and compared them with the glomerular filtration rate used in clinical practice . In 105 cases, we performed 35 cases of normal kidney, 35 cases of early kidney disease, and 35 cases of terminal kidney. The brightness of the cortex of the image was obtained and the difference in brightness between the cortex and the proximal portion was obtained by the slope. The graph of the portion which was not smooth due to the ultrasonic characteristics was used as the function regrass. The size reduction was obtained from the original data. The results were as follows: It was proportional to the glomerular filtration rate. It is considered that the algorithm can be applied to the disease if the algorithm study continues.
9.
2017.06
서비스 종료(열람 제한)
The cone beam computed tomography(CBCT) which can acquire 3-dimensions images is widely used for confirmation of patient position before radiation therapy. In this study, through the simulation using the Monte Carlo technique, we will analyze the exposure dose by cone beam computed tomography and present the standardized data. For the experiment, MCNPX(ver. 2.5.0) was used and the photon beam spectrum was analyzed after Cone beam was simulated. As a result of analyzing the photon beam spectrum, the average energy ranged from 25.7 to 37.6 keV at the tube voltage of 80 ∼ 120 kVp and the characteristic X-ray energy was 9, 60, 68 and 70 keV. As a result of using the water phantom, the percentage depth dose was measured, and the maximum dose appeared on the surface and decreased with depth. The absorbed dose also decreased as the depth increased. The absorbed dose of the whole phantom was 9.7 ~ 18.7 mGy. This is a dose which accounts for 0.2% of about 10 Gy, which is generally used for radiation therapy per week, which is not expected to have a significant effect on the treatment effect. However, it should not be overlooked even if it is small compared with prescription dose
10.
2017.06
서비스 종료(열람 제한)
In the non-destructive inspection field, we invest a lot of time and resources in developing the radiation source system to ensure the safety of the workers. However, the probability of accidents is still high. In order to prevent potential radiation accidents in advance, it is necessary to directly verify the position of the radiation source, but the research is still insufficient. In this study, we developed a monitoring system that can detect the position of the radiation source in the source guide tube in the gamma-ray irradiator. The characteristics of the radiation detector are estimated by monte carlo simulation. As a result, the radiation detector for Ir-192 gamma-ray energy was analyzed to have secondary electron equilibrium at 150 μm regardless of the semiconductor material. Also, it is expected that the gamma ray response characteristic is the best in HgI2. These results are expected to be used as a basis for determining the optimal thickness of the radiation detector located in the detection part of the future monitoring system. In addition, when developing a monitoring system based on this, radiation workers can easily recognize the danger and secure safety, as well as prevent and preemptively respond to potential radiation accidents.
