• 대한방사선기술학회지:방사선기술과학
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• 제42권2호
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• pp.99-104
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• 2019

Mammography, conducted every two years, causes cancer due to regular exposure to radiation while reducing rate of death caused by breast cancer. The study evaluates the effect of breast shielding apron made to shield off scattered radiation that occurs to the breast when the opposite side breast is mammogramed. AGD was measured using ACR phantom, composed of 50% mammary glands and 50% fat, and radiation was measured before and after wearing the apron on the breast when the opposite side of the breast is mammogramed. When CC direction mammography was conducted to a breast, the AGD was 1.84 mGy. When CC direction and MLO direction mammography were done to a breast, the average dose detected from the opposite side breast from four directions(top to bottom and medial to lateral) was $140{\mu}Gy$ with maximum dose of $256{\mu}Gy$ at medial side. After putting on the apron, the dose, caused by scattered radiation, was not detected from any of the four directions. Using of breast shielding apron is expected to minimize the radiation exposure by blocking scattered radiation to the breast shielded, when mammography is done to the opposite side breast.

• 한국재료학회지
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• 제12권8호
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• pp.682-687
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• 2002

The three-dimensional estimation on the depth and height of flaw by using the difference of radiographic contrast density was studied. First, the specimens having artificial flaws of various depths and heights were prepared and the radiographic testing was performed. The radiographic depth of flaw was investigated and estimated on the effect of the scattered radiation with the change of distance between flaw and film. The height of flaw was estimated from the radiographic test with the reference specimen. The radiographic contrast with flaw depth decreased with increasing the flaw depth. The scattered radiation increased with increasing flaw depth and varied with the location between flaw and film. However, in the case of flaw height, the contrast density increased with increasing flaw height. It is thought due to the change in volume generating the scattered radiation which reaches a film.

• 대한방사선기술학회지:방사선기술과학
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• 제11권2호
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• pp.3-15
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• 1988

When X-rays were projected into a patient, there occured the phenomena such as penetration, absorption and scattering etc. The penetrating rays were recorded on films as X-ray image used for diagnosis but scattered rays caused the radiation hazard both to the patient, specialist and technicians. The soft tissue includes many organs which are sensitive to the radiation and in may occupy $40{\sim}50%$ of body weight. Therefore X-rays should be carefully projected to the patient and it is strongly recommended to analyse the distribution of X-rays, when ever the patient is exposed to X-rays. In this study, the distribution of X-ray according to the thickness, the radiation field and the tube voltages (kVp) in soft tissue, the following results were obtained: 1. Total transmitted rays which kept the step with X-ray tube voltage (kVp) increased in proportion to the increasing of X-ray tube voltage. 2. The scattered ray rate in the total transmitted ray was not significantly found with X-ray tube voltage. 3. The affecting factors of the scattered ray rate in total transmitted ray were shown through the radiation field and the thickness. 4. The dose of scattered ray by the angle was observed more in direction of primary ray ($0^{\circ}$) and back scattering ($160^{\circ}$) than in direction of $90^{\circ}$. 5. The more the distance from phantom to the patient should be less distribution of scattered ray.

• Journal of Radiation Protection and Research
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• 제27권1호
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• pp.1-10
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• 2002

의료용 선형가속기에서 발생되는 고 에너지 광자선은 콜리메이터에 의하여 누출되며 치료두부(head), 콜리메이터, 환자를 포함한 치료실내의 모든 벽과 구성 물질들에 의하여 많은 산란선이 발생된다. 방사선치료는 종양에 따라서 최소한 40 Gy에서 80 Gy까지 조사되기 때문에 주위건강조직 특히 생식가능한 사람에 대한 생식선의 피폭선량을 평가하여야하며 종양치료에 영향을 주지 않은 범위에서 가능한 방법을 동원하여 피폭선량을 줄여야한다. 방사선 안전관리등의 기술기준에 관한 규칙(과학기술부령 제17호) 제3절 의료분야의 특별기준, 제44조(진료환자의 방사선 피폭)에 의하면 진료를 위한 환자 피폭선량을 합리적으로 달성 가능한 최소의 수준으로 유지하기 위한 절차를 구비하여야 하며 과학기술부 장관은 이에 준하는 의료시설 및 장비취급의 기술기준을 정하고 고시하여야한다고 명시 되어있다. 고 에너지방사선은 악성종양환자들의 치료성과를 향상시키는 동시에 치료후 방사선에 의한 만성효과가 발생 될 수 있기 때문에 주선속의 다양한 산란선과 누출선의 선질변화와 선량을 측정하고 생식선과 같은 주요장기를 산란선으로부터 차폐할 수 있는 기구를 제작 사용함으로서 방사선 피폭선량을 최대한으로 감소시킬 수 있었다. 고 에너지 방사선은 의료용 선형가속기(CLINAC 2100C/D. 2100C. 600C)에서 발생시킨 4, 6, 10 MV x-ray와 코발트원격치료장치(ALCYON II)의 코발트선원에서 방출되는 1.25 MV의 감마선을 이용하였다. 선량측정은 폴리스틸렌과 인체팬텀(Rando)사용하였으며 측정기는 이온함, TLD 및 필름을 사용하였다. 고 에너지 방사선에 의한 산란선은 장치의 콜리메이터 뿐만 아니라 치료실 벽 인체내부등 모든 방향에서 방사됨으로 납 벽돌에 의한 차폐율측정은 많은 변수를 가졌으며 고환인 경우에는 3면이 모두 차폐되도록 항아리모양으로 제작하였다. 태아인 경우 태아가 위치하고 있는 골반위에 육교모양의 선반을 만들고 그 위에 납 벽돌을 장치하도록 고안하였다. Co-60 감마선, 4 MV x-선, 10 MV x-선에서 발생되는 누출선량과 산란선량에 의한 평균 피폭선량은 조사면 중심으로부터 10, 30, 60cm 거리에서 조사면내 최대선량에 대하여 각각 $10^{-2},\;10^{-3},\;10^{-4}$의 비율로 측정되었으며 거리에 따라 지수함수로 줄어들었다. 흉부에 국한된 종양을 10 MV x-ray, $12{\times}12 cm^2$ 조사면으로 치료하였을 때 자궁에 받는 피폭선량은 0.9 mGy/Gy이며 고환이 받는 피폭선량은 0.6 mGy/Gy 이었으며 체장과 신장은 각각 4.8 mGy/Gy 와 2.5 mGy/Gy이다 10 MV x-선, $14{\times}14cm^2$ 조사면 경계로부터 10 cm 밖에서 납벽돌의 반가층 두께는 약 9.0 mm 이였고 20cm 밖에서는 반가층 두께가 약 6.5 mm로 측정되었다. 복부에 위치한 악성종양을 60 Gy 조사하였을 경우 태아가 위치하고 있는 자궁의 피폭선량은 약 370 mGy이고 이곳을 10 mGy이하가 되도록 차폐하려면 약 6.2 cm두께의 납 벽돌을 자궁위에 장착하여야 하며 골반치료시 고환에 10 mGy이하가 되도록 차폐하려면 약 5 cm 두께의 납 항아리가 요구된다. 고 에너지 고 준위 방사선치료시 고환은 3면을 항아리모양으로 차폐할 수 있어 피폭선량을 상당히 줄일 수 있으며 자궁인 경우 체내에서 산란된 선량의 차폐는 불가능하였다.

• 한국방사선학회논문지
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• 제10권1호
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• pp.15-19
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• 2016

본 연구는 선형가속기를 이용한 방사선 조사에서 선속평탄 여과판 사용 유무에 따른 산란선을 측정하고 자 한다. 산란선 측정은 전리함을 사용하였으며, 조사한 방사선의 에너지는 6 MV와 10 MV 이다. 갠트리 회전 중심에서 전리함을 15, 25, 35, 45 cm 거리에 위치시키고 선속평탄 여과판 사용 유무와 거리에 따른 산란선을 측정하였다. 각각의 에너지에 대하여 100 cGy 조사한 결과 6 MV에서 선속평탄 여과판을 사용하지 않은 것에서 65% 정도로 낮게 발생되었고, 10 MV 에서는 55% 정도로 낮게 발생되었다. 즉, 방사선 치료에서 결정 장기 주변의 선량은 선속평탄 여과판을 사용하지 않을 때 산란선이 적게 발생되어 방사선에 대한 확률적인 영향을 줄이기 위한 유용한 방법으로 판단되어진다.

• The Korean Journal of Pain
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• 제35권2호
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• pp.129-139
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• 2022

C-arm fluoroscopy is a useful tool for interventional pain management. However, with the increasing use of C-arm fluoroscopy, the risk of accumulated radiation exposure is a significant concern for pain physicians. Therefore, efforts are needed to reduce radiation exposure. There are three types of radiation exposure sources: (1) the primary X-ray beam, (2) scattered radiation, and (3) leakage from the X-ray tube. The major radiation exposure risk for most medical staff members is scattered radiation, the amount of which is affected by many factors. Pain physicians can reduce their radiation exposure by use of several effective methods, which utilize the following main principles: reducing the exposure time, increasing the distance from the radiation source, and radiation shielding. Some methods reduce not only the pain physician's but also the patient's radiation exposure. Taking images with collimation and minimal use of magnification are ways to reduce the intensity of the primary X-ray beam and the amount of scattered radiation. It is also important to carefully select the C-arm fluoroscopy mode, such as pulsed mode or low-dose mode, for ensuring the physician's and patient's radiation safety. Pain physicians should practice these principles and also be aware of the annual permissible radiation dose as well as checking their radiation exposure. This article aimed to review the literature on radiation safety in relation to C-arm fluoroscopy and provide recommendations to pain physicians during C-arm fluoroscopy-guided interventional pain management.

• Journal of Radiation Protection and Research
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• 제47권1호
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• pp.39-49
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• 2022

Background: For proper monitoring of the eye lens dose, an appropriate calibration factor of a dosimeter and information about the mean energies of X-rays are indispensable. The scattered X-ray energy spectra should be well characterized in medical practices where eye lenses of medical staffs might be high. Materials and Methods: Scattered X-ray energy spectra were experimentally derived for three different types of X-ray diagnostic and therapeutic equipment, i.e., the computed tomography (CT) scan, the angiography and the fluoroscopy. A commercially available CdZnTe (CZT) spectrometer with a lead collimator was employed for the measurement of scattered X-rays, which was performed in the usual manner. Results and Discussion: From the obtained energy spectra, the mean energies of the scattered X-rays lied between 40 and 60 keV. This also agreed with that obtained by the conventional half value layer method. Conclusion: The scattered X-rays to which medical workers may be exposed in the region around the eyes were characterized by means of spectrometry. The obtained mean energies of the scattered X-rays were found to match the flat region of the dosimeter response.

• 대한방사선기술학회지:방사선기술과학
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• 제5권1호
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• pp.21-34
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• 1982

When unattenuated x-ray radiation passes through the object it is transmitted and scattered from objectes and impinging on the film. During this process certain radiation is absorbed within the object and others transmitted in reduced scattering. The scattering radiation influence upon radiation image quality, confining x-ray beam which means scattering radiation produce increased fog on x-ray film image and as a consequence decrease contrast and less detail of the film there for the elimination of fog and for absorbing scattered radiation, the grid has been used between the object and the film in order to rid of scattering rays. Using grid is good method for the qualification of the better image as well as in using air gap technique. The grid is easy to manipulate and promote good efficiency which is defined by ICRU and JIS. It is the purpose to study for eliminating scattered radiation from the tissue equivalent acryl phantom using grid, we have studied and evaluated the grid permeability about the x-ray exposure, the selection of grid ratio according to phantom thickness, on x-ray exposure are performed as follows. 1. The penetrating ratio of primary x-ray is remarkably decreased by increasing of the grid ratio, but it is almost not influenced in KVP difference and phantom thickness. 2. The scattered radiation is proportionaly increased by thickness of the phantom, having nothing to do with grid ratios. 3. The relative between the penetration rate of primary and secondary x-ray is improved by increasing grid ratio, and decreased by phantom thickness, and slightly decreased by high tube voltage. 4. The grid of 5:1 and 10:1 ratio are adequate to the phantom of 10cm and 15cm thickness, respectively.

• Journal of Radiation Protection and Research
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• 제48권1호
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• pp.15-19
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• 2023

Background: Cone beam computed tomography (CBCT) is a specialized medical equipment and plays a significant role in the diagnosis of oral and maxillofacial diseases and abnormalities; however, it is attributed to risk of exposure of ionizing radiation. The aim of the study was to estimate and determine the amount of scattered radiation dose to the thyroid gland in dental CBCT during maxilla and mandible scan. Materials and Methods: The average scattered radiation dose for i-CAT 17-19 Platinum CBCT (Imaging Sciences International) was measured using a Multi-O-Meter (Unfors Instruments), placed at the patient's neck on the skin surface of the thyroid cartilage, with an exposure parameter of 120 kVp and 37.07 mAs. The surface entrance dose was noted using the Multi-O-Meter, which was placed at the time of the scan at the level of the thyroid gland on the anterior surface of the neck. Results and Discussion: The surface entrance dose to the thyroid from both jaws scans was 191.491±78.486 µGy for 0.25 mm voxel and 26.9 seconds, and 153.670±74.041 µGy from the mandible scan, whereas from the maxilla scan the surface entrance dose was 5.259±10.691 µGy. Conclusion: The surface entrance doses to the thyroid gland from imaging of both the jaws, and also from imaging of the maxilla and mandible alone were within the threshold limit. The surface entrance dose and effective dose in CBCT were dependent on the exposure parameters (kVp and mAs), scan length, and field of view. To further reduce the radiation dose, care should be taken in selecting an appropriate protocol as well as the provision of providing shielding to the thyroid gland.

• 한국방사선학회논문지
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• 제12권5호
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• pp.549-555
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• 2018

방사선 영상 기술은 피사체의 조성 및 두께에 따라 변화되는 X선의 흡수계수 차이를 기반으로 형성되는 대조도를 영상화하는 기술로서 영상 검출기에 입사하는 1차선 뿐 만 아니라 산란선이 영상 품질에 큰 영향을 미친다. 이에 본 연구에서는 피사체 두께, 조사야 변화에 따라 발생하는 산란선이 영상 품질에 미치는 영향을 고찰하고자 몬테카를로 시뮬레이션을 통하여 FSR 및 SPR 분석을 수행하였다. 연구 결과, 피사체 두께에 따른 FSR은 최대 15.3%p, SPR은 2.00 ~ 4.54로 분석되었으나, 조사야 변화에 대해서는 일정한 값을 유지하는 것으로 분석되었다. 이러한 결과를 바탕으로 피사체 두께는 영상 품질에 영향을 미치는 인자로서 고려되어야 하지만, 조사야는 영상 품질에 영향을 미치지 못하는 인자임을 검증하였다. 이러한 본 연구 결과는 영상 품질 개선을 위한 산란선에 대한 기초 자료로서 활용할 수 있을 것으로 사료된다.