• 대한방사선기술학회지:방사선기술과학
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• 제33권3호
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• pp.173-178
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• 2010

방사선 일반촬영은 크게 두 가지 유형으로 구분할 수 있는데 디지털 영상 시스템인 CR(Computed Radiography)과 DR(Digital Radiography)이 주로 활용되고 있다. 이 둘의 차이는 선량과 영상의 질 관점에서 정의할 수 있다. 본 연구에는 피부입사선량(Entrance Skin Dose, ESD)의 관점에서 환자에게 투여된 선량을 계산하고 비교하여 CR과 DR 간의 선량 차이를 연구하기 위해 8가지의 표준 영상의학적 검사(Skull AP, Skull LAT, Chest PA, Chest LAT, Abdomen AP, L-spine AP, L-spine LAT, Pelvis AP)가 고려되었다. 영상화질에 대한 평가는 진단방사선학적 영상을 위한 화질 기준에 부합하는지를 보증하기 위해 영상의학과 전문의에 의해 시행되었다. DR의 ESD는 CR의 ESD보다 낮다는 것이 확인되었다. 방사선 촬영을 담당한 방사선사가 동일인 이었고 CR과 DR의 영상 화질이 유사하거나 DR에서 조금 더 우수했기 때문에 본 연구는 고려된 검사 내에서 DR이 CR보다 선량 절감 차원에서 볼 때 더 우수한 기기라는 것을 보여준다.

• Imaging Science in Dentistry
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• 제52권1호
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• pp.33-41
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• 2022

Purpose: This study aimed to evaluate the structural complexity of craniofacial trabecular bone in multiple myeloma by fractal analysis of panoramic and lateral skull radiography, and to compare the fractal dimension values of healthy patients (HPs), pre-treatment patients (PTPs), and patients during bisphosphonate treatment (DTPs). Materials and Methods: Pairs of digital panoramic and lateral skull radiographs of 84 PTPs and 72 DTPs were selected. After application of exclusion criteria, 43 panoramic and 84 lateral skull radiographs of PTPs, 56 panoramic and 72 lateral skull radiographs of DTPs, and 99 panoramic radiographs of age- and sex-matched HPs were selected. The fractal dimension values from panoramic radiographs were compared among HPs, PTPs, and DTPs and between anatomical locations within patient groups using analysis of variance with the Tukey test. Fractal dimension values from lateral skull radiographs were compared between PTPs and DTPs using the Student t-test. Pearson correlation coefficients were used to assess the relationship between the mandible from panoramic radiographs and the skull from lateral skull radiographs. Intra-examiner agreement was assessed using intraclass correlation coefficients (α=0.05). Results: The fractal dimension values were not significantly different among HPs, PTPs, and DTPs on panoramic radiographs or between PTPs and DTPs on lateral skull radiographs (P>0.05). The mandibular body presented the highest fractal dimension values (P≤0.05). The fractal dimension values of the mandible and skull in PTPs and DTPs were not correlated. Conclusion: Fractal analysis was not sensitive for distinguishing craniofacial trabecular bone complexity in multiple myeloma patients using panoramic and lateral skull radiography.

• 대한방사선기술학회지:방사선기술과학
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• 제44권6호
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• pp.599-605
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• 2021

The International Electrotechnical Commission (IEC) 62494-1 has defined the exposure index (EI) that have a proportional relationship with the dose incident on the image receptor, and target exposure index (EI_T), deviation index (DI). In this study, an appropriate EI_T for skull radiography was established through the diagnostic reference level (DRL) and changes in DI were confirmed. Entrance surface dose (ESD) and EI were obtained using the computed radiography system displayed the EI as per IEC on console and skull phantom by experiment based on the national average exposure conditions announced in 2012 and 2019. And appropriate EI_T was established by applying the DRL in 2012 and 2019. As a results, the EI_T is changed according to the change in the DRL, and the exposure condition that becomes the ideal DI according to the change in the EI_T also has a difference of about 1.41 times. DRL is recommended to optimize the patient dose, however it is difficult to measure in real time at medical institutions whereas EI and DI are displayed on the console at the same time as exposure. When the EI_T is set based on the DRL and the DI is closed to an ideal value, it is useful as a patient dose management tool. Therefore, when the EI_T is periodically managed along with the revision of the DRLs, the patient dose can be optimized through the EI, EI_T and DI.

• 대한방사선기술학회지:방사선기술과학
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• 제8권2호
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• pp.15-19
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• 1985

The seattered-ray have a bad effect to the image of x-ray film. Therefore, to obtain the better x-ray image, the most important point is to eliminate the scattered-ray, come from the patient, and the easiest method to eliminate the scattered-ray is to use a proper grid for tube voltages. Authors made an experiment on the scattered-ray contents and the image quality in skull radiography, and obtained the results as follows; 1. The scattered-ray content in skull radiography was 83%, but it could be reduced to 35%-50% by using grid. 2. The image contrast was most increased when the using grid ratio was 8:1. 3. The image quality was not influenced by the scattered-ray contents between 32% and 45%.

• 한국방사선학회논문지
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• 제13권7호
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• pp.987-994
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• 2019

일반촬영의 저관전압 촬영에서 발생되는 저 에너지 X-선은 신체에 흡수가 많고 영상 품질 향상에는 도움을 주지 못한다. 본 연구에서는 일반 촬영에서 적정 농도를 유지하면서 환자의 피폭 선량을 줄이기 위해 농도에 따른 관전압 15%법칙과 농도에 비례하는 관전류량을 이용하여 면적 선량과 입사표면선량을 측정하여 환자의 피폭선량을 비교하였다. Hand, Knee, Abdomen, Skull 촬영에서 kVp를 115%까지 증가하면서 mAs를 50%까지 감소시키고, kVp를 85%까지 감소시키고 mAs를 200%까지 증가시키면서 면적선량과 입사표면선량을 측정하여 각각의 선량을 비교하였다. 그리고 각 영상의 5군데를 정하여 농도를 측정하고 Kruskal wallis H 검증을 하여 집단-간의 유의확률을 알아보았다. 농도를 일정하게하기 위해 관전압을 115%로 증가하고, 관전류를 50%로 감소시킨 조건에서 각 부위별 평균 면적선량과 입사표면선량을 측정한 결과 기준 선량을 100%로 할 때 각각 58.68%, 59.85%로 감소하고, 관전압을 85%로 감소하고 관전류를 200%로 증가시킨 조건에서 각각 147.28%, 159.9%로 증가하였다. 농도 변화를 비교한 결과 Hand, Knee, Abdomen, Skull 촬영 모두 유의확률 >0.05 나타나 농도 변화는 없는 것으로 나타났다. 해상력과 대조도에 영향을 주지 않는 범위에서 적정한 계산을 통해 관전압을 증가시키고 관전류를 낮게 해서 촬영하는 것이 적정농도를 유지하면서 환자의 피폭 선량을 줄이는 간단한 방법으로 사료된다.

• Imaging Science in Dentistry
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• 제53권4호
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• pp.345-353
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• 2023

Purpose: The objective of this study was to propose a method for developing a clinical phantom to reproduce various diseases that are clinically prevalent in the field of dentistry. This could facilitate diverse clinical research without unnecessarily exposing patients to radiation. Materials and Methods: This study utilized a single dry skull, which was visually and radiographically examined to evaluate its condition. Existing lesions on the dry skull were preserved, and other relevant lesions were artificially created as necessary. These lesions were then documented using intraoral radiography and cone-beam computed tomography. Once all pre-existing and reproduced lesions were confirmed by the consensus of 2 oral and maxillofacial radiologists, the skull was embedded in a soft tissue substitute. To validate the process, cone-beam computed tomography scans and panoramic radiographs were obtained of the fabricated phantom. All acquired images were subsequently evaluated. Results: Most lesions could be identified on panoramic radiographs, although some sialoliths and cracked teeth were confirmed only through cone-beam computed tomographic images. A small gap was observed between the epoxy resin and the bone structures. However, 2 oral and maxillofacial radiologists agreed that this space did not meaningfully impact the interpretation process. Conclusion: The newly developed phantom has potential for use as a standardized phantom within the dental field. It may be utilized for a variety of imaging studies, not only for optimization purposes, but also for addressing other experimental issues related to both 2- and 3-dimensional diagnostic radiography.

• Journal of Korean Neurosurgical Society
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• 제52권6호
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• pp.528-533
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• 2012

Objective : In the pediatric population the skull has not yet undergone ossification and it is assumed that the diagnostic rate of skull fractures by simple X-rays are lower than that of adults. It has been recently proposed that the diagnostic rates of skull fractures by 3-dimensional computer tomography (3D-CT) are higher than simple X-rays. The authors therefore attempted to compare the diagnostic rates of pediatric skull fractures by simple X-rays and 3D-CTs with respect to the type of fracture. Methods : One-hundred patients aged less than 12 years who visited the Emergency Center for cranial injury were subject to simple X-rays and 3D-CTs. The type and location of the fractures were compared and Kappa statistical analysis and the t-test were conducted. Results : Among the 100 pediatric patients, 65 were male and 35 were female. The mean age was $50{\pm}45$ months. 63 patients had simple skull fractures and 22 had complex fractures, and the types of fractures were linear fractures in 74, diastatic fractures 15, depressed fractures in 10, penetrating fracture in 1, and greenstick fractures in 3 patients. Statistical difference was observed for the predictive value of simple skull fractures' diagnostic rate depending on the method for diagnosis. A significant difference of the Kappa value was noted in the diagnosis of depressed skull fractures and diastatic skull fractures. Conclusion : In the majority of pediatric skull fractures, 3D-CT showed superior diagnosis rates compared to simple skull X-rays and therefore 3D-CT is recommended whenever skull fractures are suspected. This is especially true for depressed skull fractures and diastatic skull fractures.

• Journal of Radiation Protection and Research
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• 제35권3호
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• pp.111-116
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• 2010

진단을 위한 엑스선검사는 의료분야에서 전리방사선을 가장 많이 사용하고 있으며 인공 방사선피폭중 가장 높은 비율을 차지하고 있다. 우리나라에서도 진단 엑스선검사에 의한 의료피폭은 전체 방사선 피폭 중 17.4%를 차지하고 있으며 인공방사선피폭 중에서는 92%를 차지하고 있다. 두부진단을 위한 엑스선 촬영 횟수도 2007년의 경우에는 111,567건으로서 2004년 이후 매년 3% 정도의 증가 추세를 나타내고 있다. 따라서 환자선량 권고량을 국내의료기관 실정에 맞도록 설정하여 두부촬영시 환자가 받는 방사선량을 줄이고 환자의 방사선 방어를 최적화 하는 것이 필요하다. 본 논문에서는 전국 114개 의료기관에서의 두부 촬영시 피폭되는 방사선량을 인체팬텀과 유리선량계를 사용하여 측정하고 환자선량권고량(DRL, Diagnostic Reference Level)을 확립하였다. 이 결과에 따라 두부 후전면 촬영에서의 환자선량 권고량은 2.23 mGy이며, 이는 세계보건기구, 국제원자력기구 등 국제기구가 권고하는 선량 5 mGy 보다 낮았으며, 두부 측면찰영에서의 환자선량 권고량인 1.87 mGy는 국제기구가 권고하는 선량 3mG 보다 낮았다.

• Journal of Korean Neurosurgical Society
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• 제66권1호
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• pp.53-62
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• 2023

Objective : Deep learning is a machine learning approach based on artificial neural network training, and object detection algorithm using deep learning is used as the most powerful tool in image analysis. We analyzed and evaluated the diagnostic performance of a deep learning algorithm to identify skull fractures in plain radiographic images and investigated its clinical applicability. Methods : A total of 2026 plain radiographic images of the skull (fracture, 991; normal, 1035) were obtained from 741 patients. The RetinaNet architecture was used as a deep learning model. Precision, recall, and average precision were measured to evaluate the deep learning algorithm's diagnostic performance. Results : In ResNet-152, the average precision for intersection over union (IOU) 0.1, 0.3, and 0.5, were 0.7240, 0.6698, and 0.3687, respectively. When the intersection over union (IOU) and confidence threshold were 0.1, the precision was 0.7292, and the recall was 0.7650. When the IOU threshold was 0.1, and the confidence threshold was 0.6, the true and false rates were 82.9% and 17.1%, respectively. There were significant differences in the true/false and false-positive/false-negative ratios between the anterior-posterior, towne, and both lateral views (p=0.032 and p=0.003). Objects detected in false positives had vascular grooves and suture lines. In false negatives, the detection performance of the diastatic fractures, fractures crossing the suture line, and fractures around the vascular grooves and orbit was poor. Conclusion : The object detection algorithm applied with deep learning is expected to be a valuable tool in diagnosing skull fractures.

• 한국방사선학회논문지
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• 제11권5호
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• pp.387-392
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• 2017

영 유아는 사건, 사고 및 교통사고 또는 질병으로 인해 머리에 골절 및 혈관파열, 피부에 상처를 받아 병원에 내원하여 영상의학과에서 머리 검사인 전 후(Skull AP) 및 측면(Skull LAT) 촬영을 받게 된다. 머리검사에서 성인 머리(Skull) 촬영은 격자를 이용하여 촬영에 적용하면 방사선 2차선을 제거하여 영상의 대조도를 높인다. 그러나 방사선 노출조건 중 관전압을 8~10 kVp 높게 주어야 하며 환자피폭이 증가한다. 본 연구는 영 유아 머리촬영시 격자(grid)를 이용하지 않고 동등한 영상을 얻을 수 있다면 피폭선량 감소 및 Grid Cut off에 의한 아티팩트를 방지할 수 있어 연구해 보았다. 연구자는 방사선계측기 이용 방사선선량을 측정 하고 의료영상평가 방법 중에서 주관적 평가(ROC,receiver operationg characteristic)을 해 보았다. 결과에서 격자를 이용하지 않고 촬영하면 환자 피폭선량 감소와 영상 평가에서도 영 유아의 머리 촬영시 격자를 이용하지 않고 촬영을 하게 되면 머리 전 후촬영에서 0.019 mGy 와 측면촬영 0.02 mGy 피폭선량 감소가 있었고 영상평가에서도 4점을 높게 받았다. 결론으로 병원에 내원한 영 유아 머리촬영은 격자를 이용하지 않고 촬영하면 피폭 선량 감소 및 영상 아티팩트인 Grid Cut off을 방지 할 수 있고 엑스선관 수명이 연장되리라 사료된다.