• 대한치과의사협회지
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• 제50권7호
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• pp.420-430
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• 2012

Purpose: The purpose of this study was to measure the absorbed dose and to calculate the effective dose for full-mouth periapical radiography using the portable dental x-ray machine and panoramic radiography Material and Method: Thermoluminescent chips were placed at 25sites throughout the layers of the head and neck of a tissue-equivalent human skull phantom. The man phantom was exposed with the portable dental x-ray machine and panoramic unit. During full-mouth periapical radiography the exposure setting was 60 kVp, 2 mA and 0.15 ~ 0.25 seconds, while during panoramic radiography the selected exposure setting was 72 kVp, 8 mA and 18 seconds. Absorbed dose measurements were obtained and equivalent doses to individual organs were summed using ICRP 103 to calculate of effective dose. Result: In the full-mouth periapical radiography, the highest absorbed dose was recorded at the mandible body follow with submandibular glands and cheek. Using panoramic unit, the highest absorbed dose was parotid glands and the following was back of neck and submandibular glands. The effective dose in full-mouth periapical radiography using portable dental x-ray machine was 46 ${\mu}Sv$. In panoramic radiography, the effective dose was 38 ${\mu}pSv$. Conclusion: It was recommended to panoramic radiography for general check in the head and neck area because that the effect dose in the panoramic radiography was lower than the dose in the full-mouth periapical radiography using portable dental x-ray machine.

• 대한디지털의료영상학회논문지
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• 제14권2호
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• pp.15-22
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• 2012

The purpose of this study was to measure the absorbed dose and calculate the effective dose for cone beam computed tomography (CBCT) and panorama units and to estimate usefulness of x-ray protective. Rando phantom and glass dosimeters were used for dosimetry. The absorbed doses were measured at 15 organs and 14 remainder from correspond to ICRP 2007 recommendations. The absorbed dose was highest in salivary glands as measured CBCT 2.420mGy, panorama 0.307mGy. Absorbed dose in another organs were high in order of thyroid, brain, skin, esophagus. The effective dose was CBCT 0.100mSv, panorama 0.011mSv and effective dose of panorama was higher than that of CBCT by 10 times. In case of wearing x-ray protective, reducing effective dose of CBCT by 0.066mSv (66%) and panorama by 0.008mSv (72%). Effective dose were reduced by radiological shielding but it needs further optimization studies, where dosimetric data are analyzed in combination with image quality with keep the patients' exposure as low as possible.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.241-243
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• 2002

New types of protocols have been recently in development, all based on an absorbed dose-to-water with the aim of improving the accuracy of measurements of absorbed dose to water. IAEA TRS-277, the air-kerma standard-based present protocol, and IAEA TRS-398 and AAPM TG-51, the absorbed dose-to-water standard-based new one, were studied and compared theoretically and experimentally for photon beams of 6, 10, and 15 MV. NE 2571 and 3 Farmer types of ionization chambers in widely commercial use were used to determine an absorbed dose to water at the reference depth in water. Two different kinds of calibration factors were given respectively for every chamber calibrated in $\^$60/CO gamma ray beams from a Korean Secondary Standard Dosimetry Laboratory (KFDA). This work shows that there is around 1 % of difference of absorbed doses measured between two different types of calibration systems owing to different physical parameters and reference conditions used. We hope this work to help form the basis on development of new type of protocol in Korea.

• 한국콘텐츠학회논문지
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• 제15권6호
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• pp.283-289
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• 2015

현재 방사선치료는 치료효과를 높이기 위해 고에너지 광자선의 사용이 증가하고 있는 추세이다. 일반적으로 6~8 MeV 이상의 고에너지 광자선을 사용하는 경우에는, 광핵반응에 의한 광중성자가 발생됨으로써 방사선 방호의 측면에서 많은 문제를 야기 시킬 수 있다. 이에 본 연구는 MCNPX를 이용하여 방사선 치료실의 광중성자 선량분포를 분석하였다. 그 결과 10 MV와 12 MV 구간에서 급격한 흡수선량의 증가를 보였다. 이를 통해 10 MV를 시작으로 광중성자 플루언스의 급격한 증가가 흡수선량으로 연계됨을 알 수 있었다. 또한 산출된 흡수선량을 바탕으로 등가선량을 환산한 결과는 ICRP 103 권고안의 경우, 낮은 에너지 범위에서 인체의 흡수선량에 대한 2차 광자의 기여를 반영함으로써 ICRP 60 권고안에 비해 낮은 등가선량을 나타냈다.

• 한국방사선학회논문지
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• 제14권5호
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• pp.523-528
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• 2020

반려견의 사망원인 1위인 암 중 암컷에게서 가장 높은 발생률을 보이는 유방암을 대상으로 근접방사선치료 수행 시 모의모사를 이용한 흡수선량 측정을 바탕으로 적용성을 평가하고자 하였다. 모의모사를 위해 MCNPX 프로그램을 이용하였으며, 흡수선량 측정을 위해 소형견 크기의 수학적 팬텀을 제작 하였다. 흡수선량 측정결과 종양의 경우 ¹⁹²Ir에서 1.02E-12 Gy/#으로 흡수선량이 가장 높은 것으로 나타났으며, 내·외부 흡수선량에서도 동일한 경향성으로 나타났다. 따라서 반려견 유방암의 근접방사선치료 시 견종과 피폭을 고려한 적절한 선원의 선택이 고려되어야 될 것이다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 1999년도 Japanese Journal of Medical Physics
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• pp.249-252
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• 1999

• 전자공학회논문지
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• 제53권12호
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• pp.147-151
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• 2016

Standing Whole Spine 검사는 많은 병원에서 자동노출제어장치 (automatic exposure control, AEC)를 사용하고 있어 체질량지수 (body mass index, BMI)에 따라 방사선량이 조절되는 특징이 있으며, 이를 통하여 환자 별 측정 DAP (dose area product) 값을 얻을 수 있다. 하지만, 검사 시 장기의 위치에 따른 흡수선량에 관한 연구는 크게 이루어지지 않고 있으며, 이에 본 연구에서는 Standing Whole Spine 검사 시 환자의 두께정보를 대표하는 BMI와 장기의 위치에 따른 흡수선량의 분포를 평가하고자 한다. 연구의 목적을 위하여 측정된 DAP값을 이용하여 PCXMC에서 환자의 5곳의 장기를 선정 (갑상샘, 유방, 심장, 콩팥, 이자)하여 선량을 계산하였다. 결과적으로, 측정된 DAP값은 BMI에 따라 증가하는 경향을 보였지만 전방 장기인 갑상샘, 유방, 그리고 심장에서는 BMI에 따라 장기선량이 감소하는 경향을 보였다. 또한 후방장기인 콩팥과 이자에서는 BMI와 아무런 상관관계를 가지지 않았다. 결론적으로, 본 연구결과를 통하여 Standing Whole Spine 검사 시 BMI와 장기의 위치에 따라 방사선의 영향이 다르게 나타남을 증명하였다.

• Journal of Radiation Protection and Research
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• 제47권3호
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• pp.158-166
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• 2022

Background: The effects of radiation on the health of radiation workers who are constantly susceptible to occupational exposure must be assessed based on an accurate and reliable reconstruction of organ-absorbed doses that can be calculated using personal dosimeter readings measured as H_p(10) and dose conversion coefficients. However, the data used in the dose reconstruction contain significant biases arising from the lack of reality and could result in an inaccurate measure of organ-absorbed doses. Therefore, this study quantified the biases involved in organ dose reconstruction and calculated the bias-corrected H_p(10)-to-organ-absorbed dose coefficients for the use in epidemiological studies of Korean radiation workers. Materials and Methods: Two major biases were considered: (a) the bias in H_p(10) arising from the difference between the dosimeter calibration geometry and the actual exposure geometry, and (b) the bias in air kerma-to-H_p(10) conversion coefficients resulting from geometric differences between the human body and slab phantom. The biases were quantified by implementing personal dosimeters on the slab and human phantoms coupled with a Monte Carlo method and considered to calculate the bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients. Results and Discussion: The bias in H_p(10) was significant for large incident angles and low energies (e.g., 0.32 for right lateral at 218 keV), whereas the bias in dose coefficients was significant for the posteroanterior (PA) geometry only (e.g., 0.79 at 218 keV). The bias-corrected H_p(10)-to-organ-absorbed dose conversion coefficients derived in this study were up to 3.09- fold greater than those from the International Commission on Radiological Protection publications without considering the biases. Conclusion: The obtained results will aid future studies in assessing the health effects of occupational exposure of Korean radiation workers. The bias-corrected dose coefficients of this study can be used to calculate organ doses for Korean radiation workers based on personal dose records.

• 치과방사선
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• 제25권2호
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• pp.297-308
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• 1995

This study was designed to measure the absorbed dose to organs of special interest from full mouth with intraoral film(l4 films) and to compare the five periapical techniques. Thermoluminescent crystals(TLD-100 chip) were located in brain, orbit, bone marrow of mandibular ramus, bone marrow of mandibular body, bone marrow of 4th cervical spine, parotid gland, submandibular gland and thyroid gland. X -ray machine was operated at 70kVp and round collimating film holding device(XCP) and rectangular collimating film holding device(Precision Instrument) were used. The distance from the X-ray focus to the open end of the collimator was 8 inch, 12 inch and 16 inch. The results were as follows : 1. The absorbed dose was the highest in bone marrow of mandibular body(5.656mGy) and the lowest in brain (0.050mGy). 2. Generally, the lowest absorbed dose was measured from 16 inch cylinder, rectangular collimating film holding device with paralleling technique. But, in bone marrow of mandibular body and the floor of mouth, the highest absorbed dose was measured from 12 inch cylinder, rectangular collimating film holding device with paralleling techniques. 3. Comparing of five intraoral radiographic techniques, it was appeared statistically significant reduction of the absorbed doses measured with rectangular collimating film holding device compared to XCP film holding device (P<0.05). 4. No statistically significant reduction in the absorbed dose was found as cylinder length was changed(P>0.05).

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2283-2287
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• 2023

We propose in the present work how the reference glass dosimeters can be introduced, which reflects the user irradiation condition. The reference glass dosimeters are used for correcting the reader fluctuation by reading it with sample glass dosimeters at the same time. Since they can be used without annealing after irradiation for long periods, one should consider both the fading effect and the natural background dose accumulation quantitatively. We construct an empirical but practical formalism of evaluating the absorbed dose on the glass dosimeter with the fading effect and the natural background dose accumulation considered.