• Imaging Science in Dentistry
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• v.33 no.3
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• pp.151-159
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• 2003

Purpose: The purpose of this study is to evaluate the effectiveness and usefulness of newly developed personal computer-based software to eliminate the linear artifacts by the metal restorations. Materials and Methods: A 3D CT image was conventionally reconstructed using ADVANTAGE WINDOWS 2.0 3D Analysis software (GE Medical System, Milwaukee, USA) and eliminated the linear artifacts manually. Next, a 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts eliminated manually in the axial images by a skillful operator using a personal computer. A 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts were removed using a simplified algorithm program to eliminate the linear artifacts automatically in the axial images using a personal computer, abbreviating the manual editing procedure. Finally, the automatically edited reconstructed 3D images were compared to the manually edited images. Results and Conclusion: We effectively eliminated the linear artifacts automatically by this algorithm, not by the manual editing procedures, in some degree. But programs based on more complicated and accurate algorithms may lead to a nearly flawless elimination of these linear artifacts automatically.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.3006-3016
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• 2022

In this study, the images of specific prompt gamma (PG)-rays of 719 keV emitted from proton-boron reactions were analyzed using single-photon emission computed tomography (SPECT). Quantitative evaluation of the images verified the detection of anatomical changes in tumors, one of the important factors in daily adaptive proton therapy (DAPT) and verified the possibility of application of the PG-ray images to DAPT. Six scenarios were considered based on various sizes and locations compared to the reference virtual tumor to observe the anatomical alterations in the virtual tumor. Subsequently, PG-rays SPECT images were acquired using the modified ordered subset expectation-maximization algorithm, and these were evaluated using quantitative analysis methods. The results confirmed that the pixel range and location of the highest value of the normalized pixel in the PG-rays SPECT image profile changed according to the size and location of the virtual tumor. Moreover, the alterations in the virtual tumor size and location in the PG-rays SPECT images were similar to the true size and location alterations set in the phantom. Based on the above results, the tumor anatomical alterations in DAPT could be adequately detected and verified through SPECT imaging using the 719 keV PG-rays acquired during treatment.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.2
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• pp.459-475
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• 1999

Objectives : The purpose of this study is to evaluate the computed tomographic (CT) images of the paranasal sinusitis(PNS). Materials and Methods : The author examined the extent and recurring patterns of the paranasal sinusitis and some important anatomic landmarks. The author analyzed PNS images retrospectively in 500 patients who visited Chonbuk National University Hospital between January 1996 and December 1997. Results : The most frequently affected sinus was maxillary sinus (82.9％), followed by anterior ethmoid sinus(67.9％), posterior ethmoid sinus(48.9％), frontal sinus(42.0％) and sphenoid sinus(41.4％). The characteristic features of CT images of the sinusitis were sinus opacification(22.4％), mucoperiosteal thickening(34.3％), and polyposis(2.0％). Sinonasal inflammatory diseases were categorized into 5 patterns according to Babber s classification. They were 1) infundibular(13.0％), 2) ostiomeatal unit(67.4％), 3) sphenoethmoidal recess (13.0％), 4) sinonasal polyposis (9.6％) and 5) unclassifiable patterns(18.0％). The incidences of contact between sinus and optic nerve were as follows ; the incidences of contact with posterior ethmoid sinus, sphenoid sinus. both posterior sinuses were 11.4％. 66.8％, 6.3％. respectively. The incidences of contact between sphenoid sinus and maxillary nerve, vidian nerve, internal carotid artery were 74.5％. 79.2％. 45.1％. respectively. The incidences of pneumatization of the posterior ethmoid sinus were as follows ; normal 70.6％ and overriding type 29.4％. The incidences of sphenoid sinus pneumatization were as follows; normal 56.9％ , rudimentary 12.5％, pterygoid recess 22.7％, anterior clinoid recess 2.7％, and both pterygoid and anterior clinoid recess type 5.2％. Conclusions : The inflammatory sinonasal diseases were classified into five patterns using the CT of PNS, which was proven to be an excellent imaging modality providing detailed information about mucosal abnormality, pathologic patterns, and the proximity of the important structures to the posterior paranasal sinuses. This result will aid in the interpretation of CT of PNS functionally and systemically.

• Imaging Science in Dentistry
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• v.46 no.4
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• pp.245-249
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• 2016

Purpose: This study was designed to evaluate differences in the required visibility of anatomic structures according to the diagnostic tasks of implant planning and periapical diagnosis. Materials and Methods: Images of a real skull phantom were acquired under 24 combinations of different exposure conditions in a cone-beam computed tomography scanner (60, 70, 80, 90, 100, and 110 kV and 4, 6, 8, and 10 mA). Five radiologists evaluated the visibility of anatomic structures and the image quality for diagnostic tasks using a 6-point scale. results: The visibility of the periodontal ligament space showed the closest association with the ability to use an image for periapical diagnosis in both jaws. The visibility of the sinus floor and canal wall showed the closest association with the ability to use an image for implant planning. Variations in tube voltage were associated with significant differences in image quality for all diagnostic tasks. However, tube current did not show significant associations with the ability to use an image for implant planning. conclusion: The required visibility of anatomic structures varied depending on the diagnostic task. Tube voltage was a more important exposure parameter for image quality than tube current. Different settings should be used for optimization and image quality evaluation depending on the diagnostic task.

• Journal of Korean Neurosurgical Society
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• v.52 no.2
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• pp.103-106
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• 2012

Objective : To prospectively assess the diagnostic and clinical value of a new technique (3-tesla magnetic resonance myelography, 3T MRM) as compared to computed tomographic discography (disco-CT) in patients with far lateral disc herniation. Methods : We evaluated 3T MRM and disco-CT of 25 patients, whom we suspected of suffering from far lateral disc herniation. Using an assessment scale, 4 observers examined independently both 3T MRM and disco-CT images. We analyzed observer agreement and the accentuation of each image. Results : We found complete matching, and observer agreement, between high resolution images of 3T MRM and disco-CT for diagnosing far lateral disc herniation. Conclusion : We think noninvasive 3T MRM is an appropriate diagnostic tool for far lateral disc herniation as compared to disco-CT.

• Imaging Science in Dentistry
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• v.35 no.2
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• pp.83-86
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• 2005

Purpose : To evaluate the effect of deviation of mandibular positioning, by changing the mandibular plane inclination, on the measured height and width of mandible in spiral conventional tomography. Materials and Methods : By means of the Scanora multifunctional unit, cross-sectional tomograms were taken from two human dried mandibles at the mandibular angulations: -15 degree, -10 degree, -5 degree, and 0 degree. Twenty-eight sites in two dried mandibles were imaged. One examiner measured the bone heights and widths at selected sites on the images and the actual bone heights were recorded. Results : The bone heights at the four mandibular inclinations overestimated real bone heights and the mean difference between actual heights and image heights on 0 degrees was the smallest (P<0.01). The bone widths on -15 degrees were narrowest and there were significant differences between bone widths measured at the four mandibular inclinations (P<0.001). We found statistically significant differences between both bone heights and widths as measured according to the mandibular plane angle for the posterior region (P<0.01). Conclusion : The use of different mandibular positioning may result in discrepancies in heights and widths when measured from the cross-sectional tomographic images. It is suggested that the mandibular positioning may play a significant role in the measurement of mandibular heights and widths.

• Imaging Science in Dentistry
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• v.48 no.2
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• pp.147-152
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• 2018

Synovial chondromatosis is a rare metaplastic disease affecting the joints, including the temporomandibular joint (TMJ). Since its symptoms are similar to those of temporomandibular disorders, a careful differential diagnosis is essential. A 50-year-old male patient was referred with the chief complaint of pain and radiopaque masses around the left TMJ on panoramic radiography. Clinically, pre-auricular swelling and resting pain was found, without limitation of mouth opening. On cone-beam computed tomographic images, multiple calcified nodules adjacent to the TMJ and bone proliferation with sclerosis at the articular fossa and eminence were found. T2-weighted magnetic resonance images showed multiple signal-void nodules with high signal effusion in the superior joint space and thickened cortical bone at the articular fossa and eminence. The calcified nodules were removed by surgical excision, but the hypertrophic articular fossa and eminence remained. A histopathological examination confirmed the diagnosis. The patient was followed up few months later without recurrence.

• Korean Journal of Veterinary Research
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• v.59 no.2
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• pp.55-58
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• 2019

This study was performed to examine the visualization and anatomical variants of the hepatic artery with dual-phase computed tomography (CT) angiography and three-dimensional volume rendering imaging analysis in clinically normal dogs. Seven healthy beagle dogs were enrolled and underwent dual CT angiography. Arterial phase images could be obtained with multi-detector CT angiography using the fixed-scan method in these dogs. Contrast enhancement of the hepatic parenchyma was quite minimal because of the unique blood supply system of the liver. In most dogs, the main hepatic arterial branches were the right lateral branch, left branch, and right medial branch. Although hepatic arterial variation appears to be common in dogs, only one dog in this study had the caudate lobar branch as the first branch of the hepatic artery. Further study on a larger number of dogs with CT images will be needed to identify and classify the pattern of hepatic arterial variations.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1947-1954
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• 2021

In the nuclear medicine imaging, quality control (QC) process using quadrant bar phantom is fundamental aspect of evaluating the spatial resolution. In addition, QC process of gamma camera is performed by daily or weekly. Recently, Monte Carlo simulation using the Geant4 application for tomographic emission (GATE) is widely applied in the pre-clinical nuclear medicine field for modeling gamma cameras with pixelated cadmium telluride (CdTe) semiconductor detector. In this study, we modeled a pixelated CdTe semiconductor detector and quadrant bar phantom (0.5, 1.0, 1.5, and 2.0 mm bar thicknesses) using the GATE tool. Similarity analysis based on correlation coefficients and peak signal-to-noise ratios was performed to compare image qualities for various source to collimator distances (0, 2, 4, 6, and 8 cm) and collimator lengths (0.2, 0.4, 0.6, 0.8, and 1.0 cm). To this end, we selected reference images based on collimator length and source to collimator distance settings. The results demonstrate that as the collimator length increases and the source to collimator distance decreases, the similarity to reference images improves. Therefore, our simulation results represent valuable information for the modeling of CdTe-based semiconductor gamma imaging systems and QC phantoms in the field of nuclear medicine.

• Imaging Science in Dentistry
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• v.47 no.4
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• pp.255-259
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• 2017

Purpose: Underlying bone sclerosis is frequently observed in clinical settings when oral squamous cell carcinoma (OSCC) invades the jaw bone. The aim of this study was to assess the prevalence and characteristics of underlying bone sclerosis in patients with OSCC. Materials and Methods: We retrospectively reviewed the computed tomographic (CT) images of 131 patients who underwent mandibulectomy between January 2012 and December 2015 to treat OSCC. The presence, degree, and extent of underlying bone sclerosis were assessed on CT images and correlated with the following imaging patterns of bone invasion: cortical invasion, medullary invasion with a smooth margin, and medullary invasion with an irregular margin. The chi-square test was used to determine the relationships between the variables. Results: The prevalence of underlying bone sclerosis on CT images was 70.1% (47 of 67). The prevalence was 85.7% (42 of 49) in patients with medullary invasion, but it was 27.8% (5 of 18) in patients with only cortical invasion, indicating a significant increase in the prevalence of underlying bone sclerosis in patients with medullary invasion (P<.05). Aggressive patterns of bone invasion were associated with increases in the degree and extent of the underlying bone sclerosis(P<.05). Conclusion: More than two-thirds of OSCC cases with bone invasion showed underlying bone sclerosis. On CT images, reactive sclerosis in the remaining margin of the alveolar bone should not be used as the primary means to differentiate periodontal inflammatory lesions from those resulting from OSCC.