• Journal of radiological science and technology
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• v.33 no.4
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• pp.355-362
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• 2010

This study determines a range of CT parameter values in Brain CT which are minimizing patient absorption dose without compromising the image quality and optimal exposure condition. We measured dose and image noise using conventional CT parameters in Brain CT. In additon, we evaluated dose, SNR and PSNR of head phantom images while changing kVp and rotation time. In this study, effectiveness of dose that was achieved from dose reproducible experiments in conventional head CT condition is determined by changing kVp and rotation time. Dose and PSNR is related to low dose-high resolution condition. In conclusion, we suggest that using proposed conditions is effective for imaging to compare with conditions proposed by the manufacturer.

• Journal of radiological science and technology
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• v.35 no.4
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• pp.293-298
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• 2012

In digital mammography, Exposure factor were automatically chosen using by measurement breast thickness and the density of mammary gland. It may cause a increase glandular dose. The purpose of this study was to investigate optimal image quality in digital magnification mammography to decrease radiation exposure of patient dose. Auto mode gives the best image quality however, AGD showed better image quality. Image quality of manual mode passed phantom test and SNR at 55% mAs of auto mode commonly used in the digital magnification mammography. Also it could reduce AGD. According to result, manual mode may reduce the unnecessary radiation exposure in digital magnification mammography.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.287-294
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• 2015

The purpose of this study, was Let's examine the exposure dose at the time of cerebral blood flow CT scan of acute ischemic stroke patients. In particular, long-term high doses of radiation sensitive organs and we Measured using phantom and a glass dosimeter. Apply the existing protocol suggested by the manufacturer (fixed time delay technique) and the proposed new convergence protocol (bolus tracking technique), reporting to measure the dose, dose reduction was to prepare the way. Results up to 39.8% as compared to the existing protocols in a new suggested convergence protocol, a minimum of 5.8% was long-term dose is reduced. Test dose of $CDTI_{vol}$ and DLP values decreased 25%, respectively, were measured at less than recommended dose. Try checking the protocol set out in the existing based on the analysis result of the above, by applying the proposed new convergence protocol by reducing the dose would have to contribute to improved public health. It is believed to be research continues to find the optimum protocol in the other tests.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.181-189
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• 2013

The optimum exposure parameters are found when examined using the automatic mode in FFDM. improve the image quality by applying denoising algorithm and propose methods to reduce AGD(Average Grandular Dose) a patient can receive. For the experiment, Nuclear Associates Model 18-222 phantom was the used, and the entrance dose and AGD were measured. And then, Signal, Noise, SNR and FOM(Figure of Merit) were measured, compared and analyzed image denoising before and after. As the experiment result, first, SNR was the highest at Mo/Mo 23kVp and W/Rh 35kvp was the lowest for the average glandular dose. It showed to use 28kVp of W/Rh to be the best through the result of FOM. SNR was the highest at Mo/Mo 23kVp(image denoising), and it showed to W/Rh and 28kVp to be the best in the FOM result which AGD was considered at the same time. By the image denoising, it is possible to reduce noise while maintain important information in the image.

• Journal of Radiation Protection and Research
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• v.30 no.1
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• pp.17-25
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• 2005

Since the safety of nuclear power plant has been becoming a big social issue the exposure dose of radiation for workers has been one of the important factors concerning the safety problem. The existing calculation methods of radiation dose used in the planning of radiation work assume that dose rate does not depend on the location within a work space thus the variation of exposure dose by different work path is not considered. In this study, a modified numerical method was presented to estimate the exposure dose during radiation work in radwaste storage considering the effects of the distance between a worker and sources. And a new numerical algorithm was suggested to search the optimal work path minimizing the exposure dose in pre-defined work space with given radiation sources. Finally, a virtual work simulation program was developed to visualize the exposure dose of radiation doting radiation works in radwaste storage and provide the capability of simulation for work planning. As a numerical example, a test radiation work was simulated under given space and two radiation sources, and the suggested optimal work path was compared with three predefined work paths. The optimal work path obtained in the study could reduce the exposure dose for the given test work. Based on the results, tile developed numerical method and simulation program could be useful tools in the planning of radiation work.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.51-61
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• 2015

Computed tomography(CT) using radiation have potential risks. All medical radiographic examinations should require the justification of medical imaging examinations and optimization of the image quality and radiation exposure. The CT examination was higher radiation dose then general radiography. Especially pediatric CT examinations need to great caution of radiation risk. Because of pediatric patient was more sensitive of radiation exposure. Therefore, physician should consider the knowledge of CT radiation exposure indicator information for reduce a needless radiation exposure. This article was aim to understanding of CT exposure indicator, size-specific dose estimates by American Association of Physicists in Medicine (AAPM) report 204, XR 25 and understanding of CT dose reduction technique.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.275-283
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• 2013

The patient radiation dose is different depending on selection of Ion chamber when taking Chest PA which using AEC. In this paper, we studied acquiring the best diagnostic images according to selection of Ion chamber on AEC mode as well as minimizing patient radiation dose. Experimental methods were selection of Ion chamber and change of sensitivity under the same conditions as Chest PA projection. At AEC mode, two upper ion chambers sensors and one lower ion chamber sensor were divided into 7 cases according to selection of on/off. after measuring five times respectively, we obtained average value and calculated exposure dose. Image assessment was done with measured Modulation Transfer Function, Peak Signal to Noise Ratio, Root Mean Square, Signal to Noise Ratio, Contrast to Noise Ratio, Mean to Standard deviation Ratio respectively. In exposure assessment results, selection of two upper chambers was the lowest. In resolution assessment results, image of two upper chambers had the second high spatial frequency at sensitivity at 625(High) was 1.343 lp/mm. RMS value of image selecting two upper chambers was low secondly. SNR, CNR, MSR were the high value secondly. As the sensitivity was increased, radiation dose was decreased but better image could be obtained on image quality. In order to obtain the best medical images while minimizing the dose, usage of two upper ion chambers is considered to be clinically useful at sensitivity 625(High).

• Radiation Oncology Journal
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• v.10 no.2
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• pp.155-161
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• 1992

The eye lens is known to be radiosensitive organ and catarat can be induced by relatively low dose of radiation. In the treatment of head and neck tumors, shielding blocks are frequently used to minimize dose on sensitive organs. The shielding block, which is made of high atomic number materials (cerrobend), produce significant dose perturbations in megavoltage photon beams. The effects of these perturbations of eye shielding blocks are measured with film and ion chambers for the treatment of head and neck malignancies. Optimum parameters for the treatment are suggested.

• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.154-159
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• 2011

To evaluate the radiation exposure of workers participating in task where high radiation exposure is expected, two-dosimeter is typically provided radiation workers, one on the chest and the other on the back, at Korean nuclear power plants (NPPs). In a previous study, the NCRP (55:50) algorithm was selected as the optimal two-dosimeter algorithm (TDA) with various field tests and this TDA has been applied to all Korean NPPs since 2006. In 2007, the International Commission on Radiological Protection (ICRP) published the new ICRP recommendation, ICRP 103, which provides the revised weighting factors for both radiation and tissues and the new reference phantom. In this study, the applicability of current NCRP (55:50) algorithm at Korean NPPs for ICRP 103 was analyzed. As a result, it was found that the NCRP (55:50) algorithm is still effective to estimate the effective dose of workers under ICRP 103.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.827-832
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• 2018

Research on effective dose analysis of actual conditions of use based on large data is scarce. In this study, the exposure conditions of Chest X-Ray examinations used by 324 medical institutions in Korea were calculated and evaluated using computer simulations. As a result of the experiment, the effective dose in the low energy parameter bands was 0.024 mSv, followed by spleen, adrenal glands, and lung. The effective dose in the high-energy exposure parameter band was 0.123 mSv, followed by height, spleen and adrenal glands. The effective dose was 0.017 mSv when the optimal conditions considered the quality and exposure proposed in Park's study were used. The results of the study will be a reference for chest X-rays and will help reduce patient exposure.