• Title, Summary, Keyword: x-radiation

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Investigation of Image Characteristics in Phase-Contrast X-Ray Imaging (PCXI) Using a Conventional X-Ray Grid

  • Lim, Hyunwoo;Lee, Hunwoo;Cho, Hyosung;Seo, Changwoo;Je, Uikyu;Park, Chulkyu;Kim, Kyuseok;Kim, Guna;Park, Soyoung;Lee, Dongyeon;Kang, Seokyoon;Lee, Minsik
    • Journal of the Korean Physical Society
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    • v.71 no.10
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    • pp.722-726
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    • 2017
  • Phase-contrast x-ray imaging (PCXI) is an emerging technology which allows for imaging of smaller features in the examined sample than conventional attenuation-based x-ray imaging with lower x-ray dose. In this work, we investigated a relatively simple approach to PCXI using a conventional x-ray grid, which has potential to open the way to further widespread use of the technique into many application fields. We performed a simulation using a useful PCXI software developed in our previous study to investigate the image characteristics. We also performed a preliminary experiment for PCXI using a table-top setup which consists of a focused-linear x-ray grid having a 200-lines/in strip density, a microfocus x-ray tube having a $55-{\mu}m$ focal spot, and a CMOS-type flat-panel detector having a $49-{\mu}m$ pixel resolution. We successfully extracted absorption, dark-field, and phase-contrast x-ray images of much enhanced visibility at a time from the raw image of the sample by Fourier analysis. Further, we made a composite image by combining the absorption image with the colored dark-field image and compared its image characteristic to that of the absorption image alone.

- A Study on Safety of the Radiation Exposure Dose Optimization at Chest B-ray Examinations - (사업장 단체검진 시 흉부촬영의 방사선피폭 최적화 및 안전에 대한 고찰)

  • Rhim Jae Dong;Kang Kyong Sik
    • Journal of the Korea Safety Management & Science
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    • v.6 no.3
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    • pp.87-97
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    • 2004
  • The National Health Insurance Act, the Industrial Health Act and the School Health Act require chest radiography at least once a year. In chest radiographic examination, most group examinations use indirect X-ray primarily aiming at diagnosing diseases and enhancing people's health. This study purposed to minimize radiation exposure dose by comparing it between direct and indirect chest X-ray studies. According to the result of comparing and analyzing radiation exposure dose, the average incident dose and penetrating dose were 0.929μGy and 0.179μGy respectively in direct chest X-ray and 6.807μGy and 1.337μGy in indirect chest X-ray In order to minimize radiation exposure dose at direct and indirect chest X-ray, indirect X-ray should be excluded from group examination if possible. Moreover, it is necessary to control the quality of equipment (Q/A & Q/C) systematically and to avoid using unqualified equipment in order to reduce radiation exposure dose.

The reduction methods of operator's radiation dose for portable dental X-ray machines

  • Cho, Jeong-Yeon;Han, Won-Jeong
    • Restorative Dentistry and Endodontics
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    • v.37 no.3
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    • pp.160-164
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    • 2012
  • Objectives: This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Materials and Methods: Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. Results: The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. Conclusions: When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.

Development of Radiation Restrictor for Secondary Radiation Shielding of Mobile X-ray Generator (이동형 X선 발생장치의 2차 방사선 차폐를 위한 선속조절기 개발 연구)

  • Koo, Bon-Yeoul;Kim, Gha-Jung
    • Journal of radiological science and technology
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    • v.41 no.5
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    • pp.397-403
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    • 2018
  • Mobile X-ray generators are used not in the radiation area but in open space, which causes the exposure of secondary radiation to the healthcare professionals, patients, guardians, etc., regardless of their intentions. This study aimed to investigate the shielding effect of the developed radiation restrictor to block the secondary radiation scattered during the use of mobile X-ray generator. Upon setting the condition of mobile X-ray generator with chest AP, spatial doses were measured by the existence of human equivalent phantom and radiation restrictor, and measured by the existences of phantom and radiation restrictor at the same length of 100 cm. Measurements were taken at intervals of 10 cm every $30^{\circ}$ from $-90^{\circ}$ (head direction) to $+90^{\circ}$ (body direction). Upon the study results, spatial doses in all direction were increased by 45% on average when using phantom in the same condition, however, they were decreased by 64% on average when using the developed radiation restrictor. The dose at 100 cm from the center of X-ray was $3.0{\pm}0.08{\mu}Gy$ without phantom and was increased by 40% with $4.2{\pm}0.08{\mu}Gy$ after phantom usage. The dose when using phantom and the developed radiation restrictor was $1.4{\pm}0.08{\mu}Gy$, which was decreased by 66% compared to the case without using them. Therefore, it is considered the scattered radiation can be shielded at 100-150 cm, the regulation of the distance between beds, effectively with the developed radiation restrictor when using mobile X-ray generators, which can lower the radiation exposure to the people nearby including healthcare professionals and patients.

The Electrical and Radiation Detection Properties of $Au/Cd_{1-x}Zn_x/Te(x=20%)/Au$ Structure ($Au/Cd_{1-x}Zn_x/Te(x=20%)/Au$ 구조의 전기적 특성 및 방사선 탐지 특성)

  • 최명진;왕진석
    • Electrical & Electronic Materials
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    • v.10 no.1
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    • pp.39-44
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    • 1997
  • Bulk type radiation detector of Au/Cd$_{1-x}$ Zn$_{x}$Te(x=20%)/Au structure using Cd$_{1-x}$ Zn$_{x}$Te(x=20%) wafer(3x4xl mm$^{3}$) grown by high pressure Bridgman method has been developed. We etched wafer surfaces with 2% Br-methanol solution and coated gold thin film on the surfaces by electroless deposition method for 5 min. in 49/o HAuCI$_{3}$ 4H20 solution. Initial etch rates of Cd, Zn and Te were 46%, 12% and 42% respectively. After etched, the surface of wafer was slightly revealed to Te rich condition. The leakage current was increased with etch time, but it didn't exceed 3nA at 50volt. The thickness of Au film was about 100nm by Rutherford Backscattering Spectroscopy(RBS). The resolution were 6.7% for 22.1 keV photon from 109 $^{109}$ Cd and 8.2% for 59.5 keV photon from $^{241}$ Am. The radiation detector such as Au/Cd$_{1-x}$ Zn$_{x}$Te(x=20%)/Au structure was more effective to monitor the low energy gamma radiation.iation.

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Leakage and scattered radiation from hand-held dental x-ray unit (이동용 치과 X선 발생장치의 누설 및 산란 선량에 관한 연구)

  • Kim, Eun-Kyung
    • Imaging Science in Dentistry
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    • v.37 no.2
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    • pp.65-68
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    • 2007
  • Purpose: To compare the leakage and scattered radiation from hand-held dental X-ray unit with radiation from fixed dental X-ray unit. Materials and Methods: For evaluation we used one hand-held dental X-ray unit and Oramatic 558 (Trophy Radiologie, France), a fixed dental X-ray unit. Doses were measured with Unfors Multi-O-Meter 512L at the right and left hand levels of X-ray tube head part for the scattered and leakage radiation when human skull DXTTR III was exposed to both dental X-ray units. And for the leakage radiation only, doses were measured at the immediately right, left, superior and posterior side of the tube head part when air was exposed. Exposure parameters of handheld dental X-ray unit were 70 kVp, 3 mA, 0.1 second, and of fixed X-ray unit 70 kVp, 8 mA, 0.45 second. Results: The mean dose at the hand level when human skull DXTTR III was exposed with portable X-ray unit $6.39{\mu}Gy$, and the mean dose with fixed X-ray unit $3.03{\mu}Gy$ (p<0.001). The mean dose at the immediate side of the tube head part when air was exposed with portable X-ray unit was $2.97{\mu}Gy$ and with fixed X-ray unit the mean dose was $0.68{\mu}Gy$ (p<0.01). Conclusions: The leakage and scattered radiation from hand-held dental radiography was greater than from fixed dental radiography.

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Comparison Study on Changes of Antigenicities of Egg Ovalbumin Irradiated by Electron Beam or X-Ray

  • Kim, Mi-Jung;Lee, Ju-Woon;Sung, Nak-Yoon;Kim, Su-Min;Hwang, Young-Jung;Kim, Jae-Hun;Song, Beom-Seok
    • Food Science of Animal Resources
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    • v.34 no.5
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    • pp.570-575
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    • 2014
  • This study was conducted to compare the effects of two forms of radiation (electron and X-ray; generated by an electron beam accelerator) on the conformation and antigenic properties of hen's egg albumin, ovalbumin (OVA), which was used as a model protein. OVA solutions (2.0 mg/mL) were individually irradiated by electron beam or X-ray at the absorbed doses of 0 (control), 2, 4, 6, 8, and 10 kGy. No differences between the two forms of radiation on the structural properties of OVA were shown by spectrometric and electrophoretic analyses. The turbidity of OVA solution increased and the main OVA bands on polyacrylamide gels disappeared after irradiation, regardless of the radiation source. In competitive indirect enzyme-linked immunosorbent assay, OVA samples irradiated by electron beam or X-ray showed different immunological responses in reactions with monoclonal and polyclonal antibodies (immunoglobulin G) produced against non-irradiated OVA. The results indicate that electron beam irradiation and X-ray irradiation produced different patterns of structural changes to the OVA molecule.

Spatial Dose Distribution from Portable Hand-Held Dental X-Ray Equipment (이동형 치과 X선 발생장치의 공간선량 분포)

  • Han, Gyeong-Soon;Ahn, Sung-Min
    • Journal of dental hygiene science
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    • v.15 no.3
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    • pp.254-258
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    • 2015
  • To compare the stationary dental X-ray generator and the portable dental X-ray generator and to understand spatial radiation dose depended on locations by measuring spatial radiation dose of the portable dental X-ray generator. The researchers used an Ionization chamber to measure spatial radiation dose which was generated while applying X-ray radiation to real bone skull phantom with both portable and stationary dental X-ray generator. There were 4 measurement locations which were immediate anterior, right, left and posterior. Distance of measurement was 50 cm in every location and the recorded result is an average of two applications of X-ray radiation to the maxillary molar area under the condition of 70 kVp, 3 mA, 0.1 sec. Average spatial radiation dose of portable X-ray generator was $37.51{\mu}Sv$, much higher than that of stationary X-ray generator which was $10.77{\mu}Sv$ (p<0.001). The result of the spatial radiation dose of the portable X-ray generator showed a huge difference depending on types of units which varied from $17.77{\mu}Sv$ to $68.90{\mu}Sv$ (p<0.05), also depending on the measurement location, immediate anterior resulted in the highest radiation dose of $54.14{\mu}Sv$ and immediate right was the lowest of $13.60{\mu}Sv$. Immediate left and posterior, however, resulted in similar radiation dose which were $42.12{\mu}Sv$, $40.18{\mu}Sv$ (p<0.01). With this result, we claim that usage of portable dental X-ray generator should be restricted to patients who can't move and exposure to radiation should be minimized by wearing lead-apron.

A study on radiation safety education, knowledge, and practice in using portable intraoral X-ray equipment of dental hygienist's (치과위생사의 이동형 구내방사선 촬영에 관한 방사선 방어 교육, 지식, 수행에 관한 연구)

  • Ryu, Jeong-Min;Kang, Bo-Sun;Kim, Seol-Hee
    • Journal of Korean society of Dental Hygiene
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    • v.17 no.6
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    • pp.1053-1065
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    • 2017
  • Objectives: The purpose of this study is to evaluate radiation safety education, knowledge and practice of dental hygienists in using handheld portable intraoral X-ray equipment and to suggest the need for radiation safety education in using handheld portable intraoral X-ray equipment. Methods: We surveyed 223 dental hygienists from July, 2017 to August in the dental clinics of Daejeon, Seoul and Gyeonggi area. Results: Radiation safety educational experience was higher in a year's career (72.9%), than 3 years experience (32.5%) (p<0.05). 82.7% of dental clinic workers took university education for radiation safety education while 55.6% of dental hospital workers took company training (p<0.05). More than 70% of the subjects did not have experience of radiation safety education about using portable intraoral X-ray. Radiation safety knowledge was highest in a year's career (p<0.05). The cumulative dose, radiation sensitivity, and lead defense knowledge were high in all subjects, but knowledge related to scattering radiation and scattering radiation sources was low. Practice of portable intraoral X-ray safety was significantly lower than knowledge. Conclusions: Knowledge of portable intraoral radiography safety is available, but performance is poor. Even with the small amount of radiation exposure, the risk is perceivable. There is a need to actively utilize the provided radiation protection products. In order to do this, efforts should be made to improve knowledge and performance of radiation safety through not only college education but also postemployment training.

Correlation between the Portable X-ray and the Radiation Exposure dose in the Emergency Department: Cohort Study (응급실에서 이동식 단순 X-선 검사와 피폭선량과의 상관관계: 코호트 연구)

  • Kim, Yu Jung;Ahn, Hee Cheol;Sohn, You Dong;Ahn, Ji Yoon;Park, Seung Min;Lee, Won Woong;Lee, Young Hwan
    • Journal of The Korean Society of Clinical Toxicology
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    • v.11 no.2
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    • pp.101-105
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    • 2013
  • Purpose: This study was conducted in order to determine the relationship between the number of portable X-rays and the radiation exposure dose for emergency medical service providers working in the emergency department (ED). Methods: A prospective study was conducted from February 15, 2013 to May 15, 2013 in the ED in an urban hospital. Six residents, seven emergency medical technicians (EMT), and 24 nurses were enrolled. They wore a personal radiation dosimeter on their upper chest while working in the ED, and they stayed away from the portable X-ray unit at a distance of at least 1.8 m when the X-ray beam was generated. Results: The total number of portable x-rays was 2089. The average total radiation exposure dose of emergency medical service providers was $0.504{\pm}0.037$ mSv, and it was highest in the EMT group, 0.85(0.58-1.08) mSv. The average of the total number of portable X-rays was highest in the doctor group, 728.5(657.25-809). The relationship between the number of portable X-rays and the radiation exposure dose was not statistically significant(-0.186, p=0.269). Conclusion: Under the condition of staying away from the portable X-ray unit at a distance of least 1.8 m, the relationship between the number of portable X-rays and the radiation exposure dose was not statistically significant.

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