• The korean journal of orthodontics
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• v.32 no.1 s.90
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• pp.59-69
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• 2002

The purpose of this study was to evaluate the reproducibility of lateral cephalometric landmarks according to radiographic image enhancement, and to contribute to the identification of cephalometric landmarks. Lateral cephalograms of ten individuals were taken and stored into computer. The images were then enhanced up to four grades by Quick Ceph Image Pro$^{TM}$ on condition that the gray-scale equalization number was 50 and the detail enhancement number was 50. After thirty two landmarks were identified on monitor images by five observers, the deviations from the mean, the distances estimated between identified points and the mean point of five identified points, were evaluated for each landmark at each enhancement grade. Through the statistical analysis, following results were obtained. 1. In case of unenhanced radiographic images, the inter-observer reproducibility of the landmarks showed a large variation. 2. The comparison of deviation from the mean according to the degree of radiographic image enhancement for each landmark showed that the inter-observer reproducibility was significantly different at 5 landmarks. 3. The landmark of pterygomaxillary fissure showed higher reproducibility at enhancement grade 1 and 2 images than at unenhanced images. So did the landmark of posterior nasal spine at enhancement grade 1 images, and the landmark of menton at enhancement grade 2, 3 and 4 images respectively. The above results suggest that the reproducibility of some landmarks can be increased by radiographic image enhancement during the identification of the lateral cephalometric landmarks on the monitor.

• Journal of radiological science and technology
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• v.43 no.6
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• pp.489-494
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• 2020

The Law method is observing the temporal bone. There are two types of methods: the double angle method, which manipulates the center ray angle of the tube twice, and the single angle method, which manipulates once. The purpose is to increase the reproducibility of the image by making vertical incidence by making an assistive device using a 3D printer. Two assistive devices with a wedge-shaped 8.5 × 10 × 2.3 cm, an inclined surface of 7.5 cm, and an inclination angle of 15° were fabricated. Assistive devices can be combined with each other in the form of grooves, and PLA (Poly Lactic Acid) is used as a material. In the first experiment, 10 examiners operated the tube 15° in the caudad direction and 15° in the anterior direction, and measured it with a protractor to conduct a reproducibility experiment. Second, two examiners acquired vertically incidence images using the existing law method and assistive devices, and measured the distance between each measurement point to evaluate the reproducibility. The tube center ray angle reproducibility experiment was not statistically significant, but the angle difference was up to 9° between examiners. The reproducibility experiment of radiographic images was not statistically significant with the conventional method, and the method using an assistive device was statistically significant. Therefore, regardless of skill level, an image capable of securing reproducibility, which is the advantage of vertical incidence, could be obtained.

• Imaging Science in Dentistry
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• v.34 no.3
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• pp.145-150
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• 2004

Purpose: To compare three digital radiographic imaging sensors by evaluating the visibility of endodontic file tips with interobserver reproducibility and assessing subjectively the clarity of images in comparison with the x-ray film images. Materials and Methods: Forty-five extracted sound premolars were used for this study. Fifteen plaster blocks were made with three premolars each and #8, 10, 15 K-flexofiles were inserted into the root canal of premolars. They were radiographically exposed using periapical x-ray films (Kodak Insight Dental film, Eastmann Kodak company, Rochester, USA), Digora imaging plates (Soredex-Orion Co., Helsinki, Finland), CDX 2000HQ sensors (Biomedisys Co., Seoul, Korea), and CDR sensors (Schick Inc., Long Island, USA). The visibility of endodontic files was evaluated with interobserver reproducibility, which was calculated as the standard deviations of X, Y coordinates of endodontic file tips measured on digital images by three oral and maxillofacial radiologists. The clarity of images was assessed subjectively using 3 grades, i.e. plus, equal, and minus in comparison with the conventional x-ray film images. Results: Interobserver reproducibility of endodontic file tips was the highest in CDR sensor (p < 0.05) only except at Y coordinates of #15 file. In the subjective assessment of the image clarity, the plus grade was the most frequent in CDR sensor at all size of endodontic file (p < 0.05). Conclusion : CDR sensor was the most superior to the other sensors, CDX 2000HQ sensor and Digora imaging plate in the evaluation of interobserver reproducibility of endodontic file tip and subjective assessment of image clarity.

• Journal of the Korean Society of Visualization
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• v.6 no.2
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• pp.9-13
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• 2008

The reproducibility of water droplet formation which is indispensible in the investigation of a drop-on-demand piezoelectrically driven inkjet was verified by checking the size of droplet and distance from the nozzle tip of inkjet head to droplet. Based on the reproducibility of droplet formation, we visualized the formation of micro-scale droplets by acquiring consecutive images at the jetting frequency of 500 Hz for which air bubbles were not generated. Two different electric waveforms were used to drive the piezoelectric actuator. The visualization system consists of a high-speed camera that can capture images up to 250,000fps, a long-distance microscope and a halogen lamp as a light source.

• Investigative Magnetic Resonance Imaging
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• v.23 no.1
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• pp.26-33
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• 2019

Purpose: Diffusion tensor imaging (DTI) data must be analyzed by an analyzer after data processing. Hence, the analyzed data of DTI might depend on the analyzer, making it a major limitation. This paper reviewed previous DTI studies reporting the repeatability and reproducibility of data from the corticospinal tract (CST), one of the most actively researched neural tracts on this topic. Materials and Methods: Relevant studies published between January 1990 and December 2018 were identified by searching PubMed, Google Scholar, and MEDLINE electronic databases using the following keywords: DTI, diffusion tensor tractography, reliability, repeatability, reproducibility, and CST. As a result, 15 studies were selected. Results: Measurements of the CSTs using region of interest methods on 2-dimensional DTI images generally showed excellent repeatability and reproducibility of more than 0.8 but high variability (0.29 to 1.00) between studies. In contrast, measurements of the CST using the 3-dimensional DTT method not only revealed excellent repeatability and reproducibility of more than 0.9 but also low variability (repeatability, 0.88 to 1.00; reproducibility, 0.82 to 0.99) between studies. Conclusion: Both 2-dimensional DTI and 3-dimensional DTT methods appeared to be reliable for measuring the CST but the 3-dimensional DTT method appeared to be more reliable.

• Journal of radiological science and technology
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• v.41 no.6
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• pp.539-543
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• 2018

Telometer is a supplementary filming device that improves the image quality and minimizes the motion unsharpness by enhancing the reproducibility of diagnostic images because it applies constant pressure (force) to the affected area. The stress-radiogram which is widely used to provide the o-bjective quantitative stability of knee ligament is reported in literature as the most suitable method to evaluate the stability of ligament and it is advised to use the Telometer. In order to evaluate the image reproducibility of the Telometer, the collateral ligament which is the most vulnerable among the ligaments consisting of the knee joint, the stress-radiogram was executed in the order of the Telometer, the push pull gauge and the conventional stress radiogram. Then, SPSS (Statistical Package for the Social Science) for Windows 22.0 was used for comparison and evaluation. According to the results of comparison and evaluation, the standard errors and standard deviations became smaller in the order of the Telometer, the push pull gauge, the conventional stress radiogram while the image reproducibility was higher in the order of the Telometer, the push pull gauge, the conventional stress radiogram. Therefore, it is considered that the use of the TELOS for stress-radiogram would enhance the quality of patient diagnostic images and the work performance of radiologists.

• The Journal of Korean Society for Radiation Therapy
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• v.33
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• pp.71-78
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• 2021

Purpose: To evaluate the inter-fractional position and respiratory reproducibility of lung and liver tumors using pressure conserving type(P-type) abdominal compressor in volumetric modulated arc therapy(VMAT). Materials and methods: Six lung cancer patients and three liver cancer patients who underwent VMAT using a P-type abdominal compressor were included in this study. Cone-beam computed tomography(CBCT) images were acquired before each treatment and compared with planning CT images to evaluate the inter-fractional position reproducibility. The position variation was defined as the difference of position shift values between target matching and bone matching. 4-dimensional cone-beam computed tomography(4D CBCT) images were acquired weekly before treatment and compared with planning 4DCT images to evaluate the inter-fractional respiratory reproducibility. The respiratory variation was calculated by the magnitude of excursions by breathing. Results: The mean ± standard deviation(SD) of overall position variation values, 3D vector in the three translational directions were 1.1 ± 1.4 mm and 4.5 ± 2.8 mm for the lung and liver, respectively. The mean ± SD of respiratory variation values were 0.7 ± 3.4 mm (p = 0.195) in the lung and 3.6 ± 2.6 mm (p < 0.05) in the liver. Conclusion: The use of P-type compressor in lung and liver VMAT was effective for stable control of inter-fractional position and respiratory variation by reproduction of abdominal compression. Appropriate PTV margin must be considered in treatment planning, and image guidance before each treatment are required in order to obtain more stable reproducibility

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.2
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• pp.61-67
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• 2014

Objectives: The present study was conducted to determine the reproducibility of peri-implant tissue assessment using the new implant success index (ISI) in comparison with the Misch classification. Materials and Methods: In this descriptive study, 22 cases of peri-implant soft tissue with different conditions were selected, and color slides were prepared from them. The slides were shown to periodontists, maxillofacial surgeons, prosthodontists and general dentists, and these professionals were asked to score the images according to the Misch classification and ISI. The intra- and inter-observer reproducibility scores of the viewers were assessed and reported using kappa and weighted kappa (WK) tests. Results: Inter-observer reproducibility of the ISI technique between the prosthodontists-periodontists (WK=0.85), prosthodontists-maxillofacial surgeons (WK=0.86) and periodontists-maxillofacial surgeons (WK=0.9) was better than that between general dentists and other specialists. In the two groups of general dentists and maxillofacial surgeons, ISI was more reproducible than the Misch classification system (WK=0.99 versus WK non-calculable, WK=1 and WK=0.86). The intra-observer reproducibility of both methods was equally excellent among periodontists (WK=1). For prosthodontists, the WK was not calculable via any of the methods. Conclusion: The intra-observer reproducibility of both the ISI and Misch classification techniques depends on the specialty and expertise of the clinician. Although ISI has more classes, it also has higher reproducibility than simpler classifications due to its ability to provide more detail.

• The korean journal of orthodontics
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• v.38 no.5
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• pp.314-327
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• 2008

Objective: The purpose of this study was to evaluate the reproducibility of measurements representing asymmetry of the mandible and to identify which landmarks would be more useful in 3-dimensional (3D) CT imaging. Methods: Facial CT images were obtained from forty normal occlusion individuals. Eighteen landmarks were established from the condyle, gonion, and menton areas, and 25 measurements were constructed to represent asymmetry of the mandible; 8 for ramus length, 12 for mandibular body length, 1 for condylar neck length, 2 for frontal ramal inclination, and 2 for lateral ramal inclination. Inter- and intra-examiner reproducibility of the measurements was evaluated. Results: Inter-examiner reproducibility of the measurements proved to be high except for 3 measurements. Intra-examiner reproducibility also proved to be high except for 2 measurements. Inter- and intra-examiner reproducibility of the measurements including Gonion proved to be low. Conclusions: The results of the present study indicate that the landmarks and measurements constructed in 3D CT images can be used for the diagnosis of facial asymmetry.

• Imaging Science in Dentistry
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• v.32 no.4
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• pp.213-219
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• 2002

Purpose : Computed radiography (CR) has been used in cephalometric radiography and many studies have been carried out to improve image quality using various digital enhancement and filtering techniques, During CR image acquisition, the frequency rank and type affect to the image quality. The aim of this study was to compare the diagnostic quality of conventional cephalometric radiographs to those of computed radiography. Materials and Methods : The diagnostic quality of conventional cephalometric radiographs (MO) and their digital image counterparts were compared, and at the same time, six modalities (M1-M6) of spatial frequency-processed digital images were compared by evaluating the reproducibility of 23 cephalometric landmark locations. Reproducibility was defined as an observer's deviation (in mm) from the mean between all observers. Results and Conclusion: In comparison with the conventional cephalometric radiograph (MO), Ml showed statistically significant differences in 8 locations, M2 in 9, M3 12, M4 in 7, M5 in 12, and M6 showed significant differences in 14 of 23 landmark locations (p < 0.05). The number of reproducible landmarks that each modality possesses were 7 in M6, 6 in M5, 5 in M3, 4 in M4, 3 in M2, 2 in Ml, and 1 location in MO. The image modality that observers selected as having the best image quality was M5.