• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.64-65
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• 2010

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.242-243
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• 2010

• Journal of radiological science and technology
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• v.35 no.4
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• pp.299-308
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• 2012

To perform patient dose surveys in major interventional radiography procedures as a mean of inter-institutional comparison and of establishing reference dose levels with the ultimate goal of optimizing patient doses in the field of interventional radiography. We reviewed international patient dose survey data in the literature and measured patient dose in major interventional radiography procedures (TACE, AVF, PTBD, TFCA, GDC embolization). ESD(Entrance Skin Dose) was measured using TLD chips attached to the patient skin and ED(Effective Dose) was calculated using angiography unit-derived DAP. A survey of patient dose in interventional radiography procedures were also performed with a questionnaire for interventional radiologists and we proposed a guideline for optimizing patient doses in the field of interventional radiology. The patient dose survey data in interventional radiography procedures were very rare in literature compared with those in diagnostic radiography procedures. In TACE, the mean ED was 25.43 mSv and the mean ESD was 511.75 mGy. The mean ED of TACE was not high, but the cumulative dose should be checked, due to longer procedure TACE. In TFCA, the mean ED was 22.6 mSv and it was relatively high compared with data of other countries. In GDC embolization, the mean ED was not available, because GDC embolization was performed with old Image-Intensifier-type unit and there has no unit-installed ionization chamber. Also, the mean ESD of GDC embolization was up to 2,264 mGy and further studies are needed to calculate the net ED of GDC embolization. Patient dose occurred during interventional radiography procedures are high related with the difficulty of the procedure, fluoroscopy time, the number of angiographies and the treatment protocol. Therefore, continuous education and efforts should be made to optimize the patient dose in the field of interventional radiology.

• Journal of radiological science and technology
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• v.38 no.2
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• pp.101-106
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• 2015

Recently, There has been a growing interests in exposure dose to the patient who take a examination using radiation. The radiological technologists should be concerned about the exposure dose to patients and make an efforts to reduce the patient dose without decreasing the image quality. In the case of foreign, the exposure dose of general X-ray examination have been managed by standard value of exposure dose using dose area product (DAP) and entrance surface dose (ESD) dosimeter. This study is to compare DAP and ESD in skull anterior posterior (AP), chest posterior anterior (PA), and abdomen AP projections of phantom by using DAP and ESD dosimeter. In the results, there were no differences between DAP and ESD dosimeter.

• Journal of the Korean Society of Radiology
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• v.6 no.4
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• pp.281-290
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• 2012

The difference of radiation dose of MDCT due to different protocols between hospitals was analyzed by CTDI, DLP, the number of Slice and the number of DLP/Slice in 30 cases of the head, the abdomen and the chest that have 10 cases each from MDCT examination of the department of diagnostic imaging of three general hospitals in Gyeongsangbuk-do. The difference of image quality, CTDI, DLP, radiation dose in the eye and radiation dose in thyroid was analyzed after both helical scan and normal scan for head CT were performed because a protocol of head CT is relatively simple and head CT is the most frequent case. Head CT was significantly higher in two-thirds of hospitals compared to A hospital that does not exceed a CTDI diagnostic reference level (IAEA 50mGy, Korea 60mGy) (p<0.001). DLP was higher in one-third of hospitals than a diagnostic reference level of IAEA 1,050mGy.cm and Korea 1,000mGy.cm and two-thirds exceeded the recommendation of Korea and those were significantly higher than A hospital that does not exceed a diagnostic reference level (p<0.001). Abdomen CT showed 119mGy that was higher than a diagnostic reference level of IAEA 25mGy and Korea 20mGy in one-third. DLP in all hospitals was higher that Korea recommendation of 700mGy.cm. Among target hospitals, C hospital showed high radiation dose in all tests because MPR and 3D were of great importance due to low pitch and high Tube Curren. To analyze the difference of radiation dose by scan methods, normal scan and helical scan for head CT of the same patient were performed. In the result, CTDI and DLP of helical CT were higher 63.4% and 93.7% than normal scan (p<0.05, p<0.01). However, normal scan of radiation dose in thyroid was higher 87.26% (p<0.01). Beam of helical CT looked like a bell in the deep part and the marginal part so thyroid was exposed with low radiation dose deviated from central beam. In addition, helical scan used Gantry angle perpendicularly and normal scan used it parallel to the orbitomeatal line. Therefore, radiation dose in thyroid decreased in helical scan. However, a protocol in this study showed higher radiation dose than diagnostic reference level of KFDA. To obey the recommendation of KFDA, low Tube Curren and high pitch were demanded. In this study, the difference of image quality between normal scan and helical scan was not significant. Therefore, a standardized protocol of normal scan was generally used and protective gear for thyroid was needed except a special case. We studied a part of CT cases in the local area. Therefore, the result could not represent the entire cases. However, we confirmed that patient's radiation dose in some cases exceeded the recommendation and the deviation between hospitals was observed. To improve this issue, doctors of diagnostic imaging or technologists of radiology should perform CT by the optimized protocol to decrease a level of CT radiation and also reveal radiation dose for the right to know of patients. However, they had little understanding of the situation. Therefore, the effort of relevant agencies with education program for CT radiation dose, release of radiation dose from CT examination and addition of radiation dose control and open CT contents into evaluation for hospital services and certification, and also the effort of health professionals with the best protocol to realize optimized CT examination.

• Journal of Radiation Protection and Research
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• v.30 no.4
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• pp.175-183
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• 2005

Dose distribution of Korean radiation workers classified by occupational categories was analyzed. Statistics of the occupational radiation exposure(ORE) in 2002 of the radiation workers in diagnostic and dental radiology were obtained from the Korea Food and Drug Agency(KFDA) who maintains the database for individual radiation dose records. Corresponding statistics for the rest of radiation workers were obtained by processing the individual annual doses provided by the Korea Radioisotope Association(KRIA) after deletion of individual information. The ORE distribution was classified in term of 28 occupational categories, annual individual dose levels, age groups and gender of 52733 radiation workers as of the year of 2002. The total collective dose was 66.4 man-Sv and resulting average individual ORE was 1.26 mSv. Around 80% of the workers were exposed to minimal doses less than 1.2 mSv. However, it appeared that the recorded doses exceeded 20 mSv for 43 workers in the industrial radiography and for 147 workers in the field of radiology. Particularly, recorded doses of 23 workers in radiology exceeded the annual dose limits of 50 mSv, which is extraordinary when the working environment is considered. It is uncertain whether those doses are real or caused by careless placing of dosimeters in the imaging rooms while the X-ray units are in operation. No one in the workforce of 16 operating nuclear power plant units was exposed over 20 mSv in 2002. Number of workers was the largest in their 30's of age and the mean individual dose was the highest in their 20's. Women were around 20% of the radiation workers and their average dose was around one half of that of man workers.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.273-279
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• 2022

In order to reduce the absorbed dose given to the patient during dental radiography, a sensor that inserts a shield into the intraoralsensor was designed. Using the designed sensor, the change in absorbed dose depending on whether or not a shield was used was evaluated. The system used to evaluate the absorbed dose is VEX-S300C from Vatech, and the energy spectrum of X-rays was obtained through SPEKTR simulation based on the irradiation conditions of 65 kV, 3 mA, and 0.15 sec, and the number of photons for each energy was derived. After designing the system through Genat4 Application for Tomographic Emission(GATE) simulation, the energy spectrum obtained was used as a radiation source to calculate the absorbed dose. Lead was used for the shield, and simulations were performed at 0.1 mm thickness intervals from 0.1 mm to 0.5 mm was evaluated. In the case of using an X-ray field with a diameter of 60 mm, the decrease in absorbed dose according to the presence or absence of a shield decreased exponentially as the thickness of the shield increased. In addition, when a 20 mm × 30 mm field was used, the absorbed dose was significantly reduced even when no shield was used, and it was confirmed that the absorbed dose was further reduced when a shield was used.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.187-188
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• 2011

저 에너지 방사선검사 시 부득이하게 방사선 노출을 받게 되는 방사선 작업종사자나 환자의 보호자가 위치와 거리에 따른 방사선 피폭 선량의 감소 방안을 알아보고자 한다. Ion chamber mode 2026c, Reader기 20X6-1800을 사용하여 구강내 검사와 구강외 검사의 각각 검사실과 조정실에서의 관전압의 변화, 관전류와 조사시간의 변화, 조사방향의 변화에 따라 선량을 측정하였다. 그 결과 검사실 안에서는 최고선량이 평균 $702.8{\mu}R$으로 측정 되었으며, 조정실 안에서 측정하였을 경우 $20{\mu}R$이하의 낮은 선량을 보였으며, 후방검사보다 측방검사가 낮은 선량으로 나타났다. 방사선검사 시 위치와 거리에 따른 조사선량을 비교 분석하여, 적절한 거리 확보와 조사되는 중심방사선을 기준으로 측방($90{\sim}135^{\circ}$)에 위치함으로써 방사선 방어에 도움을 줄 것이며, 차폐문을 이용하여 방사선 피폭으로부터 감소 효과를 볼 수 있을 것이다.

• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.27-37
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• 2012

From Jan 2002 to June 2011, we evaluated 4419 cases of radiation dose of 323 radiation related individuals consist of physician, nurses, technician and others in local C national university hospital. On annual analysis, year 2003 ranked the highest and 2007 the lowest dose. Dose was relatively higher in male than female. Dose was highest in 30s on age basis analysis. Dose was high in order of physician, nurse, and technician. Average radiation dose was high in order of cardiovascular center, radiologic intervention ceter, radiologist individuals, and fluoroscopic contrast study room. Those doses did not excess the standard dose recommended by ICRP (20mSv/year). However unlike average dose, there are wide variations of dose in individuals. Therefore radiation related workers should do one's best in personal radiation exposure dose management for achievement of minimum dose of radiation.

• 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.