• Korean Journal of Digital Imaging in Medicine
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• v.5 no.1
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• pp.98-101
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• 2002

대조도와 관용도사이의 손실 교환은 투사 방사선 촬영에 있어서 잘 알려져 있고 또한 오랫동안 지속되어온 영상의 질에 있어서의 제약이었다. 전자적인 영상획득의 도입으로 한 영상 내에 넓은 영역의 X-Tay 노출을 포획하는 것이 가능해 졌다. 그러나, 진단에 필요한 세부영역 들을 위해 적절한 대조도를 유지하는 반면, 일반적으로 기대되는 관용도 범위 이외의 정보가 시각화 되어지는 것과 같은 영상의 rendering과 displaying의 문제가 남아 있었다. 이 문서에 묘사되는 EVP(Enhanced Visualization Processing)는 이 문제를 중점적으로 다룬다. 방대한 진단용 CR 영상 데이터베이스로부터 선택된 14개의 검사유형 당 각각 5개의 영상들을 포함한, 총 70개의 영상들을 사용하여 임상 보고서가 제출되었다. 각 영상에 대해, control rendering은 현재 개발되어 있는 automatic tone scaling algorithm(자동 톤 스케일 알고리즘)에 의해 생성되었고, test rendering은 그 control of image에 EVP를 인가함에 의해 생성되었다. 10명의 radiologist들은 각자 개별적으로 140개의 이미지들(70개의 test renderings와 70개의 control renderings)을 9점의 진단 상의 품질 척도로 평가했다. EVP는 세부 대조도의 부당한 손실 없이 증가된 노출 관용도를 제공했다. 많은 영상에서 EVP는 과소 투과 영역에서의 정보의 손실을 줄여주고, 반면 과다 투과 영역의 밝게 빛나는 현상을 실제적으로 감소시켰다. 진단상의 품질 평가는 EVP image와 control image 모두 평균적으로 높았다. 그럼에도 EVP images의 평균 등위는 control image의 그것보다 1 단계 완전히 높은 범위에 있는 것으로 평가되었다. 쌍으로 그 영상들을 보면, EVP images의 76%가 일치하는 control images의 평가 단계보다 1 또는 그 이상 높은 범주인 것으로 평가되었고, 반면 control image의 6% 만이 일치하는 EVP 영상보다 우수한 것으로 평가되었다. 유사한 결과가 연구된 14개의 검사유형에 대해 획득되었다.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.387-392
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• 2017

When an infant has visited a hospital due to skull fracture, the rupture of a blood vessel, or skin wounds on the head resulted from an incident, accident, traffic accident, or disease, he/she becomes to undergo anterior/posterior and lateral skull imaging, which is a head test at the department of radiology. In the head test, if the adult skull imaging grid is applied to the imaging, the secondary radiation will be removed to enhance the contrast of the image. However, among the radiation exposure conditions, the tube voltage should be enhanced by 8~10 kVp leading to an increase in the patient exposure. The present study was conducted under assumption that if the same images can be obtained from infant skull imaging without using the skull imaging grid, the exposure dose will be reduced and the artifacts due to grid cut off can be prevented. The researcher measured the radiation dosage using a radiation meter and conducted the subjective evaluation (ROC, receiver operating characteristic) among medical image evaluation methods. Based on the results, when the images were taken without using the grid, the exposure dose was reduced by 0.019 mGy in the anterior/posterior imaging and by 0.02 mGy in the lateral imaging and the image evaluation score was higher by 4 points. In conclusion, if the images of the skulls of infants that visited the hospital are taken with out using the grid, the exposure dose can be reduced, the image artifacts due to grid cut off can be prevented, and the lifespan of the X-ray tube will be extended.

• The Journal of the Korea Contents Association
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• v.9 no.6
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• pp.247-255
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• 2009

This study aims to provide basic data for establishing the safety and health plan by investigating the exposure conditions in the facilities registering business about handling radiations and radioactive isotopes in Korea. dose levels(working space, worker location) of the workers in 153 facilities were measured using surveymeter, and individual exposure concentration[(shallow dose(SD), depth dose(DD)] in 27 facilities using thermal luminescence dosimeter(TLD). In accordance with the measurement results by business type[fire fighting prevention business(FFPB, n=10), financial insurance business(FIB, n=3) and other facilities(n=140)] using surveymeter, those three business type groups showed difference (p<0.000). Dose levels of worker location for FFPB and FIB were significantly higher than 10.0 ${\mu}Sv$/hr, the allowable standard for radiations and radioactive isotopes, and they were higher 109.3 times(p<0.000) and 187.5 times(p<0.000) than those in other facilities. The concentration of TLD[FFPB(n=10), other facility (n=17)] in DD of FFPB was significantly higher than that in other facility(p=0.05). In accordance with the analysis result on relationship between surveymeter and TLD, the dose on working space and worker location(r=0.406, p<0.05), worker location dose and SD(r=0.453, p<0.05), worker location dose and DD(r=0.553, p<0.01), and SD and DD(r=0.927, p<0.001) had all related each other. It is urgently required to change FFPB and FIB from the facilities requiring registration for handling radiations and radioactive isotopes to the facilities that shall get permission for handling radiations and radioactive isotopes by reestablishing the legal administration area, for safety and health of radiation occupants.

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.659-667
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• 2018

The purpose of this study was to determine the effect of body mass index (BMI) on entrance surface air kerma (ESAK) in abdominal X-ray radiography using automatic exposure control (AEC). This study included 321 patients who underwent abdominal X-ray using AEC, and we correlated ESAK with height, weight, BMI and compared mean ESAK according to BMI grades (Underweight, Normal, Overweight, Obese 1, Obese 2). As a result, Weight ($R^2=0.777$, p<.001) and BMI ($R^2=0.835$, p<.001) were positively associated with ESAK, but no significant association was found between height ($R^2=0.075$, p<.001) and ESAK. The mean ESAK with respect to BMI grades showed statistically significant difference and in the post-hoc analysis, the existence of 5 subgroups at the significance level of 0.05 indicated that there were differences in the ESAK in all BMI grades. Also, as the increment of ESAK between two neighboring BMI grades increases from Underweight to Obese 2, the exposure dose dramatically increased as the BMI increased. Thus, an excessive exposure dose due to increasing BMI when using AEC should be acknowledged and Efforts to reduce dose should be taken, such as: by fixing the exposure conditions.

• Journal of radiological science and technology
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• v.29 no.3
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• pp.185-195
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• 2006

Purpose: This study investigated the status of radiation exposure doses since the establishment of the "Regulations on Safety Management of Diagnostic Radiation Generation Device" in January 6, 1995. Method: The level of radiation exposure in people engaged or having been engaged in radiation-related industries of inspection organizations, educational organizations, military units, hospitals, public health centers, businesses, research organizations or clinics over a 5 year period from Jan. 1, 2000 to Dec. 31, 2004 was measured. The 149,205 measurement data of 57,136 workers registered in a measurement organization were analysed in this study. Frequency analysis, a Chi-square test, Chi-square trend test, and ANOVA was used for data analysis. Results: Among 57,136, men were 40,870(71.5%). 50.3% of them were radiologic technologists, otherwise medical doctors(22.7%), nurse(2.9%) and others(24.1%). The average of depth radiation and surface radiation during the 5-year period were found to decrease each year. Both the depth radiation and surface radiation exposure were significantly higher in males, in older age groups, in radiological technologists of occupation. The departments of nuclear medicine had the highest exposure of both depth and surface radiation of the divisions of labor. There were 1.98 and 2.57 per 1,000 person-year were exposed more than 20 mSv(limit recommended by International Commission on Radiological Protection) in depth and surface radiation consequently. Conclusion: The total exposure per worker was siginifcantly decreased by year. But Careful awareness is needed for the workers who exposed over 20 mSv per year. In order to minimize exposure to radiation, each person engaged in a radiation-related industry must adhere to the individual safety management guidelines more thoroughly. In addition, systematic education and continuous guidance aimed at increasing the awareness of safety must be provided.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.29-34
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• 1993

Experiments have been carried out with C3H mouse fibrosarcoma (FSa II) to determine the effect of different sequence and time intervals between irradiation and administration of cis-diammihedichloroplatinum (cis-DDP) with gross tumors (6 mm in diameter), microscopic tumors (3 days after transplantation of $10^3$ cells) and cells in culture. The drug was administered either 24, 12, 8, 4, 2, 1, 0.5 hour before irradiation, immediately before irradiation, or 0.5, 1, 2, 4, 8, 12, 24 hours after irradiation. In case of in vivo studies, tumor growth delay was used as an end point. Clonogenic cell surviving fraction was used for in vitro studies. Tumor growth delay for gross tumor after 10 Gy radiation plus 10 mg/kg cis-DDP ranged from 6.3 to 10.66 days and the enhancement ratio ranged from 1.37 to 2.23. The most effective combination was when cis-DDP was given 4 hours before irradiation. Tumor growth delay for microscopic tumor after 5 Gy of radiation and 5 mg/kg of cis-DDP ranged from 3.55 to 11.98 days with enhancement ratio from 2.05 to 6.92. Microscopic tumors showed response significantly greater than additive in every time interval and the most effective treatments were when cis-DDP was given 2 and 1 hour before irradiation. In in vitro experiment, the surviving fraction after 6 Gy of radiation and 1 hour exposure to 4 ${\mu}M$ cis-DDP fluctuated as a function of time between treatments, but the difference between maximum and minimum surviving fractions was very small. According to the above results the sequence and time interval between irradiation and chemotherapy is very critical especially for the management of microscopic tumors as in the case of postoperative adjuvant treatment.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.851-857
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• 2023

The purpose of this study is to investigate the effect of changes in collimation size and sub ROI on exposure index(EI) in hand radiography, present collimation size and EI suitable for average hand size of Koreans, and present the effect of changes in sub ROI on EI. The subjects of this study were hand-wrist phantom, and the exposure conditions were set to 55 kVp, 125, mA, and 6.25 mAs, and source to image receptor distance was applied to 110 cm. Based on the vendor recommended sub-ROI (18.7" × 18.7", 8" × 10", 8" × 7.4", 6" × 7.4")and the textbook's recommended sub-ROI 8" × 10", each obtaining 30 images, and comparing the EI shown in the equipment. The EI according to the change in the size of the collimation were 1663.7±4.52, 8"×10" is 1489.1±4.49, 8"×7.4" is 1716.9±3.00, 6"×7.4" is 168.7±3.66 for each EI, and the average value of each value was statistically significant. The average EI according to the sub ROI change was 1489.1±4.49 for SS, LS was 1694.8±5.19 for AEC, 2052.9±5.96, VR was 1548.3±3.20, and HR was 1663.2±4.33. The appropriate field size considering the hand size of Koreans was found to be 8"×7.4". In addition, when the field size increases based on the generally known field size (8"×10") during hand radiography, the EI value changes from a maximum of 15% to a minimum of 11%, and the sub ROI shape based on sub ROI 'SS' Depending on the change, the EI value increased from a maximum of 37% to a minimum of 3%.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.3 no.2
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• pp.87-90
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• 2007

It's important that detect early caries of deciduous and permanent teeth to prevent dental caries and prevserve teeth, especially on proximal surface of deciduous teeth. The reason is that their prominent pulp horn lead to pulp treatment easily due to rapid caries progression. There are conventional exploring, visual inspection and radiographic exam for early caries detection. But, the standard method for diagnosing dental caries is subject and cavitation may be accelerated during exploring procedure. Caries can be diagnosed up to 40% mineral loss with radiograph. $DIFOTI^{(R)}$ (Digital Imaging Fiber-Optic TransIllumination) is diagnostic imaging system for early caries detection using fiber-optic illumination. It is possible that remineralize the tooth surface without tooth preparation and conserve the tooth structure by using $DIFOTI^{(R)}$.

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.254-255
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• 2009

국내 경수로 원전의 경우, 원전의 효율적, 경제적 운영차원에서 장주기 운전으로 패턴을 바뀌면서 핵연료봉 표면상에 크러드(crud)의 침적량은 점점 증가하는 경향을 나타내고 있다. 이러한 경향은 원자로의 출력 제어와 직결되면서 이에 대한 문제 해결을 위한 대표성이 있는 시료의 채취와 재현성이 있는 부식 생성물의 측정이 요구되어져 왔다. 원자로 계통 내에서 부식생성물의 농도변화에 대한 평가, 특히 입자농도가 증가되어지면 축방향 출력편차(Axial Offset Anomaly, AOA)가 발생될 수 있는 위험에 노출되거나, 핵연료 교체를 위해 발전소 정지시(shut down) 부식생성물의 방출이 급격히 증가되는 것으로 나타났다. 특히 입자성을 띤 물질은 존재의 특성상 이들 물질에 대한 대표시료의 채취가 어려울 뿐 아니라 grab 채취로 인해, 분석결과에 대한 재현성이 낮으며 계통 선량율의 제어와 작업자 피폭관리에 많은 어려움이 뒤따르고 있어 선진 원전 운영국에서는 앞 다투어 대표시료를 채취 할 수 있는 capillary sampling 법이나 integrated sampling법을 적용해 오고 있다. 본 논문에서는 국내 경수로 원전에서 일반적으로 사용하고 있는 grab sampling 법에 대한 문제점 파악과 해외 원전에서 사용 중인 capillary sampling 법의 국내 적용 가능성에 대해 살펴보았다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.111-122
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• 2014

As radiotherapy has become one of the widely used techniques in cancer treatment, accurate tracking of patient's respiratory motion is considered to be more important in treatment planning and dose calculations. Inaccurate motion tracking can cause severe issues such as errors in target/normal tissue delineation and increasing the volume of healthy tissues exposed to high doses. Different methods have been introduced to estimate the respiratory motion, but most of them require some electronic devices or expensive materials. As an inexpensive and easy to use alternative to the previous methods, we propose a new 3D respiratory motion tracking method by using stereo vision techniques of detecting and decoding visual coded markers.