• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.473-479
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• 2019

PET-CT improves performance and reduces the time by combining PET and CT of spatial resolution, and uses CT scan for attenuation correction. This study analyzed PET image evaluation. The condition of the tube voltage and current of CT will be changed using. Uniformity phantom and resolution phantom were injected with 37 MBq $^{18}F$ (fluorine ; 511 keV, half life - 109.7 min), respectively. PET-CT (Biograph, siemens, US) was used to perform emission scan (30 min) and penetration scan. And then the collected image data were reconstructed in OSEM-3D. The same ROI was set on the image data with a analyzer (Vinci 2.54, Germany) and profile was used to analyze and compare spatial resolution and image quality through FWHM and SI. Analyzing profile with pre-defined ROI in each phantom, PET image was not influenced by the change of tube voltage or exposure dose. However, CT image was influenced by tube voltage, but not by exposure dose. When tube voltage was fixed and exposure dose changed, exposure dose changed too, increasing dose value. When exposure dose was fixed at 150 mA and tube voltage was varied, the result was 10.56, 24.6 and 35.61 mGy in each variables (in resolution phantom). In this study, attenuation image showed no significant difference when exposure dose was changed. However, when exposure dose increased, the amount of dose that patient absorbed increased too, which indicates that CT exposure dose should be decreased to minimum to lower the exposure dose that patient absorbs. Therefore future study needs to discuss the conditions that could minimize exposure dose that gets absorbed by patient during PET-CT scan.

• Korean Journal of Digital Imaging in Medicine
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• v.11 no.2
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• pp.101-107
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• 2009

With the recent development of diagnosis using radiation and increasing demand of the medical treatment, we need to minimize radiation exposure dose. So, This is the method which reduce patient dose by measuring surface dose of radiographic change factor and by comparing theoretical and actual dose, when we take an X-ray which is generally used. By changing the factor of kV, mAs, FSD, whose range is 60 to 120 kV, 20 to 100 mAs, 80 to 180 cm, we compared theoretical surface dose with actual surface dose calculated by the simple calculation program, Bit system, and NDD-M method As a result, when kV and mAs were higher, theoretical surface dose and actual surface dose were more increased. but the higher FSD was, the more decreased surface dose was. According to this, the error were measured about 0.1 to 0.2 mGy in low dose part and about 0.7 to 1.5 mGy in high dose part. Therefore, this shows that theoretical surface dose calculation method is more correct in low dose part than in high dose part. In conclusion, we will have to make constant efforts which can reduce patient and radiographer's exposure dose, studying methods which can predict patient's radiation exposure dose more exactly.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.433-438
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• 2019

The medical institutions use radiation generating devices and radioactive isotopes to diagnose and treat patients. The patient transporter performs work in an environment that is more likely to be exposed to radiation when compared with the general public, such as inevitably entering the radiation management area for patient transfer, or transferring the isotope-administered patient at a short distance. For this reason, we conducted a study to determine the degree of exposure of the patient transporter. The 12 patient transporters working at Incheon A General Hospital are eligible. From April 1, 2019 to April 30, 2019, the dosimeter was used in the chest for one month and the accumulated dose was measured. The dosimeter used was a Optically Stimulated Luminescence Dosimetry (OSLD) and the dose reading was OSLD Microstar Reading System. As a result of cumulative dose measurement for one month, the average of the deep dose was 0.13 mSv and the surface dose was 0.13 mSv, and the cumulative dose for one month was multiplied by 12 to estimate the cumulative dose expectation As a result, the average of the deep dose and the surface dose were 1.52 mSv and 1.51 mSv, respectively. It is necessary to classify the patient transporter as a frequent visitor in order to measure and manage the exposure dose, increase the knowledge of protection against radiation through education and training, and prevent radiation trouble through medical examination.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.489-492
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• 2014

This thesis provides the design of system software for the management of radiation dose that is generated using computer tomography(CT). Because radiation exposure is different depending on the difference in sensitivity to each part for each of the patient's body, if we will be able to manage an appropriate amount of radiation, it is possible to estimate the radiation exposure of the patient as a result. Recently, radiation leakage incident of Japanese nuclear power plant was in the news internationally and there is a growing interest not only a nuclear power plant, to medical radiation exposure. In spite of the fact that currently safety management of radiation is under control only the workers of the radiation involved, exposure management of patients until now have been required. Surgery and inspection using the radiation in Korea will increase, due to this medical exposure has increased, but it is a reality that medical institution don't know the level of radiation exposure applied to the patient. Therefore a system for managing the radiation exposure of the patient from the medical institution is required. This paper proposes a design of a software program to manage the radiation exposure of CT is an typical imaging tool to use the radiation in the medical institution. By check the amount of radiation dose and set the limit of dose, we would help to optimize the medical exposure of the patient.

• Journal of radiological science and technology
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• v.20 no.2
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• pp.56-62
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• 1997

To evaluated the image quality and the patient exposure for the chest radiography, its fundamental imaging properties were investigated. The basic imaging properties were evaluated by measuring characteristic curves, relative speeds, average gradient, and patient exposure dose. The image qualities were evaluated by using a rotating meter. It was found that the film gradient of SRO750/SRH system was 3.13 and that of SRO750/HR-C30 was 1.77. The ratio of SRO1000/TMH to FS/RP-1 was 1 to 18.2. It was possible to visualize the static image when the exposure time was less than 2.5 msec in patient that had respiratory excessive motion, heart beat and natural physical motion, and less than 8.5 msec in normal. The ratio of medical exposure dose compared with our method was 1 to 25 in the routine chest radiography and maximum was 1 to 70. In estimation of the image quality in same cases, we found that the image of SRO1000/SRH and TMH of super sensitive systems was the same results. We found that these super sensitive screen-film systems were available for the chest radiography considering the relationship between the image quality and patient exposure.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.269-271
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• 2002

It is reported that exposure for the patient and the medical staff from IVR is large. Direct measurement of patient exposure is difficult, since the measurement disturbs reading of images. The fluorescence glass-dosimeter system consisting of small-size glass chips is developed in recent years. Owing to its small size and physical characteristics, direct monitoring of surface dose may be feasible. The dose measurement for patient and medical staff during head interventional radiology (IVR) examinations was tried by using the fluorescence glass-dosimeter system. A dose response of the glass dosimeter is almost linear in large dose range but its energy dependency is high. About 20% variation of sensitivity was observed in the effective energy of 45-60keV which was used in IVR. In spite of this shortcoming, the fluorescence glass-dosimeter system is a convenient means for a dose monitoring during IVR performance.

• Journal of radiological science and technology
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• v.21 no.1
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• pp.52-58
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• 1998

We can and must improve the diagnostic images using available knowledge and technology. At the same time we must strive to reduce the patient's integral and entrance radiation dose. Reducing the integral dose to the patient during the radiologic procedure is a primary concern of the patient, especially the pediatric patient, the radiologist and the technologist. A 100cm focal film distance generally is used for most over-table radiography. The early x-ray tubes and screen film combinations required long exposures, which often resulted in motion artifacts. But nowaday, we have the generators and x-ray tubes that can deliver the energy necessary in a very short time and the receptors that can record the information just as rapidly. And, we performed this studies to evaluate the patient exposure dose and the image quality by increasing focal film distance in diagnostic radiography. There are many factors which affected to exposure factor, but we studied to verify of FFD increase, only. Effect of increasing the focal film distance to a 140 cm distance was tested as follows; 1. The focal film distances were set at 100, 120, and 140cm. 2. A 18cm acryl(tissue equivalent) phantom was placed on the table top. 3. An Capintec 192 electrometer with PM 05 ion chamber was placed at the entrance surface of the phantom, and exposure were made at each focal film distances. 4. The procedure was repeated in the same manner as above except the ion chamber was placed beneath the phantom at the film plane. 5. Exit exposure were normalize to 8mR for each portions of the experiment. Based on the success of the empirical measurements, a detailed mathematical analysis of the dose reduction was performed using the percent depth dose data. The results of this study can be summerized as followings ; 1) Increasing FFD from 100 cm to 140 cm, we would create a situation that would have a significant effect on the overall quality of radiograph and achive the 17.42% reduction of entrance dose and the 18.95% reduction of integral dose that the patient receives. 2) Thickness of Al step wedge for equal film density increased with the long distance. 3) Increasing FFD, Magnification of image was lowered. 4) Resolution of image also increased with the FFD. As the results described above, we strongly recommend using the long FFD to provide better information for our patients and profession in abdomen radiographic studies.

• Journal of radiological science and technology
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• v.24 no.1
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• pp.17-22
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• 2001

Medical X-ray examination are increased double for the last $6{\sim}8$ years. Therefore a patient exposure dose should be decrease half every 7 years. We made an experiment on copper filter thickness to decrease a patient exposure dose up to half and compared to the Image quality by MTF. The results as follow 1. A thin region like extremities needs a thicker Cu filter as compared a thick region. 2. 1/2 reduction filter must be thicker when kVp Increase. 3. Exposure factor should be increas when using 1/2 reduction filter ; extremity is 4.0 times, chest 2.9 times, skull 1.62 times, and abdomen 1.58 times 4. The MTF of using 1/2 reduction filter is lower than without filter. But no difference of visual image. 5. 1/2 reduction filter compared with double speed screen showed almost same image quality.

• Journal of radiological science and technology
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• v.21 no.1
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• pp.29-34
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• 1998

The purpose of simple abdomen erect projection is to see the fluid level which indicates gastrointestinal ileus or free air due to perforation. we do not have to insist on low kVp technique in simple abdomen erect position as long as we can detect the fluid level and free air shadow. Therefore, the author tried to decrease patient dose by high kVp technique and to improve the image quality due to motion artifact by reduction of exposure time. [Methods] Experiment 1. * screen/film SRO1000/HRH * exposure factor : $140\;kvp{\pm}5\;kv$ with added filters, 200 mA, 0.01 sec * phantom : Acryles : 15.0 cm(equivalent to 17 cm body thickness) 17.5 cm(equivalent to 21 cm body thickness) 20.0 cm (equivalent to 25 cm body thickness) With the exposure factor for same film density($D=0.8{\pm}0.1$) and with the materials above, we tried to find out entrance skin dose and gonad dose for both male and female. Experiment 2. Burger's phantom radiography were checked to see whether there was any change of image quality according to the kVp and the added filters. Experiment 3. Using rotating meter(self made), we examined the motion artifact and the exposure time limitation. [Results and conculution] 1. Using high voltage technique of 140 kVp with added filter, Skin dose, testicle dose and ovary dose decrease to 89.3%, 47% and 71.4% respectively compare to 70 kVp technique, 2. No great changes of Burger's phantom image has detected as from 70 kVp to 140 kVp and the air hole size of Burger's phantom over 0.028 cc(Diameter 3 mm, hight 4 mm) can be distinghished. 3. 0.01 sec(1 pulse) exposure time is possible in the single phase full wave rectification that why we can quitely reduce the unsharness caused by patient's movement.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.2
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• pp.71-76
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• 2011

Because interventional procedure operates looking at premier as real time when perate intervention enemy, by patient is revealed during suitableness time in radiation, side effect such as radiation injury of skin is apt to happen. It established by purpose of study that measure exposure dose that patient receives about these problem, and find solution for radiation injury and repletion method. In this study, we used Rando phantom of identical structure with the human body which becomes accomplished with 4 branch ingredient of the attempt and system equivalent material them and absorbed dose were measured by TLD. According to the laboratory, it shows that operations such as TFCA procedure or uterine myoma embolization are more dangerous than TACE procedure. If both operations are inspected during a short time, it is not affected in being bombed. However, it can lead to palliative agenesis or depilate, definitive agenesis only if operations are repeated more than three times. Dose distibution based on experiment, to reduce radiation exposure to patients result from reduction of scatter ray as we control field size of radiation and protection of side organs except for tumor. also we knew that we can protect patients form radiation exposure, if we increas SOD and decrease SID.