• Nuclear Engineering and Technology
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• 제53권9호
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• pp.3035-3043
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• 2021

Epidemiological research has revealed that radiation exposure can cause cataracts. The Korean nuclear regulatory body has proposed the reduction of the occupational dose limit for the lens of the eye from 150 mSv/y to 100 mSv/5y, with an additional limitation of not exceeding 50 mSv/y for a specific year, taking into account the recommendations of the International Commission on Radiological Protection, and the International Atomic Energy Agency. This means that radiation workers should receive the same level of radiation safety for the lens of the eye as for whole-body protection. Korean nuclear power plants (NPPs) are conducting research to establish the radiation protection program for the lens of the eye. In terms of the preliminary results of the implementation of the radiation protection program for the lens of the eye dedicated to Korean NPPs, this review article summarizes the current state of understanding of the regulations, technical guidance, eye lens dosimeters, and radiation field conditions resulting in lens dose.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.335-339
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• 2024

Employees of nuclear medicine facilities performing medical procedures with the use of open radioactive sources require continuous detailed control of exposure to ionizing radiation. Thermoluminescent (TL) detectors placed in dosimeters: for the whole body, for lenses, ring and wrist dosimeters were used to assess exposure. The highest whole-body exposure of (1.70 ± 1.09) µSv/GBq was recorded in nurses administering radiopharmaceutical to patients. The highest exposure to lenses and fingers was recorded for employees of the quality control zone and it was (8.08 ± 2.84) µSv/GBq and a maximum of (1261.46 ± 338.93) µSv/GBq, respectively. Workers in the production zone received the highest doses on their hands, i.e. (175.67 ± 13.25) µSv/GBq. The measurements performed showed that the analyzed workers may be classified as exposure category A. Wrist dosimeters are not recommended for use in isotope laboratories due to underestimation of ionizing radiation doses. Appropriately selected shields, which significantly reduce the dose received by employees, must be used in isotope laboratories. Periodic measurements confirmed that the appropriate optimization of exposure reduces the radiation doses received by employees.

• Imaging Science in Dentistry
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• 제43권2호
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• pp.77-84
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• 2013

Purpose: This study aimed to provide comparative measurements of the effective dose from direct and indirect digital panoramic units according to phantoms and exposure parameters. Materials and Methods: Dose measurements were carried out using a head phantom representing an average man (175 cm tall, 73.5 kg male) and a limbless whole body phantom representing an average woman (155 cm tall, 50 kg female). Lithium fluoride thermoluminescent dosimeter (TLD) chips were used for the dosimeter. Two direct and 2 indirect digital panoramic units were evaluated in this study. Effective doses were derived using 2007 International Commission on Radiological Protection (ICRP) recommendations. Results: The effective doses of the 4 digital panoramic units ranged between $8.9{\mu}Sv$ and $37.8{\mu}Sv$. By using the head phantom, the effective doses from the direct digital panoramic units ($37.8{\mu}Sv$, $27.6{\mu}Sv$) were higher than those from the indirect units ($8.9{\mu}Sv$, $15.9{\mu}Sv$). The same panoramic unit showed the difference in effective doses according to the gender of the phantom, numbers and locations of TLDs, and kVp. Conclusion: To reasonably assess the radiation risk from various dental radiographic units, the effective doses should be obtained with the same numbers and locations of TLDs, and with standard hospital exposure. After that, it is necessary to survey the effective doses from various dental radiographic units according to the gender with the corresponding phantom.

• Journal of Radiation Protection and Research
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• 제1권1호
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• pp.10-14
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• 1976

공동(空洞)크기가 LiF 열형광선량계(熱螢光線量計)의 감응(感應)에 미치는 영향(影響)을 포리에틸렌 매질내(媒質內)에 삽입(揷入)한 구형(球型) 열형광선량계공동(熱螢光線量計空洞)의 가상계(假想系)에서 이론적(理論的)로 연구(硏究)하였다. 크기가 다른 반경(半徑)을 가진 구형공동(球型空洞)의 감응(感應)은 최근(最近)의 공동이론(空洞理論)을 適用(적용)하여 입사광자(入射光子) 에너지의 함수(函數)로서 계산(計算)하였다. 그반경(半徑)은 1.578mm에서 6.528mm까지 취하였고 입사광자(入射光子)에너지는 0.02MeV에서 0.3Mev까지의 범위를 택하였다. 결과(結果)로서 매질내(媒質內)에 삽입(揷入)한 공동(空洞)으로서의 LiF 열형광선량계(熱螢光線量計)의 감응(感應)은 입사광자(入射光子)의 에너지는 물론 선량계(線量計) 자체(自體)크기의 함수(函數)라는 것을 발견(發見)하였다.

• 대한소아치과학회지
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• 제39권3호
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• pp.273-279
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• 2012

목적: 상악 정중과잉치의 영상진단 시 시행되는 콘빔 전산화단층촬영술에 대한 환자의 방사선 피폭을 유효선량으로 평가하고, 치근단 및 파노라마방사선촬영술의 방사선피폭과 비교하고자 하였다. 재료 및 방법: 선량 측정용 두경부 마네킨의 23부위에 열형광선량계 소자를 위치시키고 해당 방사선촬영술을 시행하였다. 열형광선량계 판독기로 흡수선량를 측정하고 방사선 조사된 조직의 비율을 곱하여 방사선 가중선량을 구한 후, 국제방사선방호위원회에서 2007년에 공지한 조직 가중계수를 이용하여 유효선량을 구하였다. 결과: 조직 및 기관의 흡수선량은 콘빔 전산화단층촬영술, 치근단방사선촬영술 그리고 파노라마방사선촬영술에서 뺨, 하악체, 이하선에서 가장 높았다. 유효선량은 콘빔 전산화단층촬영에서는 48 ${\mu}Sv$, 치근단방사선촬영술에서는 2 ${\mu}Sv$ 그리고 파노라마방사선촬영술에서는 18 ${\mu}Sv$였다. 결론: 상악 정중과잉치 진단 시, 추가적인 진단학적 정보를 제공하지만, 콘빔 전산화단층촬영술은 일반 치근단 및 파노라마 방사선촬영술보다 방사선피폭이 크다.

• 센서학회지
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• 제7권5호
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• pp.313-318
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• 1998

LiF에 Mg, Cu, P를 활성제로 첨가한 고감도의 LiF:Mg,Cu,P TLD를 제작하고, 잠상퇴행과 열처리조건에 따른 열형광 특성의 변화와 재사용성을 조사하였다. 제작한 LiF:Mg,Cu,P TLD는 시판중인 TLD-700(Harshaw Chemical Co.)에 비해 25.3배 열형광 강도가 높았으며, 실온에서 1개월 간 보관했을 때는 주 peak의 잠상퇴행이 나타나지 않았고, $100^{\circ}C$에서는 7일 경과 후 50% 정도 열형광강도가 감소하였다. 또한 $260{\sim}320^{\circ}C$의 온도 영역에서 열처리에 따른 열형광 특성 변화를 조사하였으며, TLD가 초기의 열형광 강도를 회복하여 재사용이 가능한 열처리 온도와 시간을 각각 $280^{\circ}C$, 10분으로 정하였다.

• Nuclear Engineering and Technology
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• 제6권4호
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• pp.239-247
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• 1974

방사선 안전관리의 효과적인 연구를 위해 유사인체 모형을 설계, 제작하였다. 이 모형의 치수는 한국인의 체격과 근사하게 맞추었으며 두께 2.5cm인 포리에칠렌판 35매로 구성되었다. 유사인체모형의 표면에 착용한 열형광 설량계(Disc type TLD)로써 외부 ${\gamma}$-방사선에 의한 신체특정부위의 피폭선량을 측정하였으며, 아울러 깊이에 따른 흡수선량에 대해서 열형광 선량계(micro rod type TLD)로써 측정하여 결정장기 부위의 각단면에 대한 등가선량선을 얻었다. 선량측정은 방사선 작업자의 작업환경조건에 유사하도록 유사인체 모형에 대해 배치하고 여러 입사방항에 대해서 실시하였다. 그 결과 Cs-137, ${\gamma}$-방사선에 대하여 두께 20cm인 유사인체 모형에서의 감쇄는 0.439였으며 이는 보고된 자료들과 잘 일치하였다.

• 치과방사선
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• 제20권2호
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• pp.315-333
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• 1990

This study was performed to measure the skin absorbed doses from full mouth standard intraoral radiography (l4 exposures) in bisecting angle and paralleling techniques. Thermoluminescent dosimeters were used in a phantom. Circular tube collimator(60㎜ in diameter, 20㎝ in length) and rectangular collimator(35㎜ × 44㎜, 40㎝ in length) were set for bisecting angle and paralleling techniques respectively. All measurement sites were classified into 8 groups according to distance from each point of central rays. The results were as follows: 1. The skin absorbed doses from the paralleling technique were significantly decreased than those from the bisecting technique in both points at central ray and points away from central ray. The percentage rates of decrease were greater at points away from central ray than those at central ray. 2. The skin absorbed doses at the lens of eye, parotid gland, submandibular gland and thyroid region were significantly decreased in paralleling techniuqe, but those of the midline of palate remained similar in both techniques. 3. The highest doses were measured at the site 20mm above the point of central ray for the mandibular premolars in bisecting angle technique and at the point of central ray for the mandibular premolars in paralleling techniques. The lowest doses were measured at the thyroid region in both techniques.

• Imaging Science in Dentistry
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• 제40권1호
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• pp.15-23
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• 2010

Purpose : This study was designed to compare the effective doses from low-dose and standard-dose multi-detector CT (MDCT) scanning protocols and evaluate the image quality and the spatial resolution of the low-dose MDCT protocols for clinical use. Materials and Methods : 6-channel MDCT scanner (Siemens Medical System, Forschheim, Germany), was used for this study. Protocol of the standard-dose MDCT for the orthodontic analysis was 130 kV, 35 mAs, 1.25 mm slice width, 0.8 pitch. Those of the low-dose MDCT for orthodontic analysis and orthodontic surgery were 110 kV, 30 mAs, 1.25 mm slice width, 0.85 pitch and 110 kV, 45 mAs, 2.5 mm slice width, 0.85 pitch. Thermoluminescent dosimeters (TLDs) were placed at 31 sites throughout the levels of adult female ART head and neck phantom. Effective doses were calculated according to ICRP 1990 and 2007 recommendations. A formalin-fixed cadaver and AAPM CT performance phantom were scanned for the evaluation of subjective image quality and spatial resolution. Results : Effective doses in ${\mu}Sv$ ($E_{2007}$) were 699.1, 429.4 and 603.1 for standard-dose CT of orthodontic treatment, low-dose CT of orthodontic analysis, and low-dose CT of orthodontic surgery, respectively. The image quality from the low-dose protocol were not worse than those from the standard-dose protocol. The spatial resolutions of both standard-dose and low-dose CT images were acceptable. Conclusion : From the above results, it can be concluded that the low-dose MDCT protocol is preferable in obtaining CT images for orthodontic analysis and orthodontic surgery.

• Journal of Radiation Protection and Research
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• 제22권3호
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• pp.135-141
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• 1997

열처리 특성의 연구는 열형광선량계를 재 사용하는데 있어서 중요하다. 최근 개발된 디스크 형태 (직경 4.5 mm, 두께 약 $90mg/cm^2$)의 LiF:Mg,Cu,Na,Si Teflon TLD의 열처리 조건을 구하기 위하여 조사전열처리, 판독과정 및 판독 후 열처리의 순서로 연구하였다. Teflon TLD의 감마선 조사는 $^{60}Co$ 0.1 Gy로 하였다. LiF:Mg,Cu,Na,Si Teflon TLD의 열처리 특성의 연구는 전기로와 판독장치를 이용하여 열처리 온도와 열처리 시간을 변화시키면서, 측정반복횟수에 따른 열형광강도 변화를 관찰하는 방법으로 수행하였다. LiF:Mg,Cu,Na,Si Teflon TLD의 열처리 조건은 조사전 열처리를 $80^{\circ}C$에서 1 시간 한 후 $280^{\circ}C$까지 판독하고 판독 후 열처리를 $270^{\circ}C$에서 20 초간 하는 것으로 결정되었고, 이 조건에서 10 회 반복측정시 원래의 열형광강도는 5%의 감소를 보였다.