• Imaging Science in Dentistry
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• v.45 no.4
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• pp.205-211
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• 2015

Purpose: This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods: Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearman's rho correlation coefficient test. Results: The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Conclusion: Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

• The Magazine of the IEIE
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• v.8 no.1
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• pp.16-32
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• 1981

물리학적인 측면과 공학적인 측면에서의 CT(computerized tomography)의 최근 동향과 발전 과정을 되돌아 보고 의료 현장에서 실제 사용되고 있거나 아직 연구되고 있는 CTsystem의 성능과 그 특성에 대해 기술해 보았다. 또한 CT의 역사적인 발전과정, tomophysics 및 chemistry, system의 구성, detector 및 sensing diode, 신호의 수집과 처리를 위한 전자회로, computer system 및 주변 연산장치등에 대해서 고찰하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.776-787
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• 1998

This paper analyzes the local specific absorption rates (SAR's) averaged over 1 g and 10 g in a human head model in contact with a mobile phone operating at 835 MHz. The used numerical method is a total field finite-difference time-domain (FDTD) technique. The phone was simulated with a conducting box, a plastic case, and a whip antennal composed of a monopole and a helix. The discrete human model of the spatial resolution 3 mm is based on Magnetic Resonance Imaging (MRI), computerized tomography (CT) and anatomical images. The near field and far field and far field patterns were analyzed for extended and retracted phone. The two methods to take the volumes of the weights, 1 g or 10 g in tissue are proposed and compared to offer a reproductive technique for SAR estimations.

• Journal of Korean Neurosurgical Society
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• v.39 no.2
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• pp.125-129
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• 2006

Objective : The purpose of this study is to identify any differential point in computerized tomographic[CT] findings between aneurysmal subarachnoid hemorrhage[ASAH] and traumatic subarachnoid hemorrhage[TSAH], which sometimes make us not confident in differentiation. Methods : CT of 142 ASAH and 82 TSAH patients over the last 2 years were retrospectively reviewed. We evaluated the thickness of SAH, the laterality of sylvian cisternal hemorrhage, the location, the number of involved cisterns, and the associated other lesions between two types of SAH. Results : Suprasellar cisterns and sylvian cisterns were most prominently and frequently involved cisterns in ASAH but cortical sulci and sylvian cisterns were most frequently involved in TSAH. Intraventricular and intracerebral hemorrhage were frequently seen in ASAH. Thickness of SAH over 1mm, bilateral sylvian SAH, multiple cisternal SAH were in favor of ASAH. The number of involved cisterns were more frequently seen in ASAH than in TSAH. In ASAH, bilateral sylvian hemorrhages were more frequently seen than in TSAH. Skull fracture, subdural hematoma, subgaleal hematoma, and hemorrhagic contusion were frequently associated with TSAH. Conclusion : As a result of our study, the authors conclude that when IVH, hydrocephalus, thick SAH > 1mm bilateral sylvian SAH, and multiple cisternal SAH are seen in CT, immediate angiography should be performed to rule out cerebral aneurysms whether associated with other traumatic lesions or not.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2717-2722
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• 2013

Background: The objective of this research is the computed axial tomography (CT) imaging grading of radiation induced pneumonitis (RP) and its correlation with clinical and radiotherapeutic parameters. Materials and Methods: The chest CT films of 20 patients with non-small cell lung cancer who have undergone threedimensional conformal radiation therapy were reviewed. The proposed CT grading of RP is supported on solely radiological diagnosis criteria and distinguishes five grades. The manifestation of RP was also correlated with any positive pre-existing chronic obstructive pulmonary disease (COPD) history, smoking history, the FEV1 value, and the dosimetric variable V20. Results: The CT grading of RP was as follows: 3 patients (15%) presented with ground glass opacity (grade 1), 9 patients (45%) were classified as grade 2, 7 patients (35%) presented with focal consolidation, with or without elements of fibrosis (grade 3), and only one patient (5%) presented with opacity with accompanying atelectasis and loss of pulmonary volume (grade 4). Both univariate and multivariate analysis revealed as prognostic factors for the radiological grading of RP the reduction of FEV1 and the V20 (P=0.026 and P=0.003, respectively). There was also a significant (P<0.001) correlation of radiological grading of RP with FEV1 and V20 (spearman rho 0.92 and 0.93, respectively). Conclusions: The high correlation of the proposed radiological grading with the FEV1 and the V20 is giving a satisfactory clinical validity. Although the proposed grading scale seems relevant to clinical practice, further studies are needed for the confirmation of its validity and reliability.

• Investigative Magnetic Resonance Imaging
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• v.23 no.1
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• pp.75-80
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• 2019

Metastasis of rhabdomysarcoma to the breast is a very rare manifestation in adult males. Herein, we report a case of metastasis from embryonal rhabdomyosarcoma in the left hypothenar muscle that presented as a breast mass in a 38-year-old man, who four months later expired because of multiple bone metastases related to pancytopenia. We describe the various imaging findings, including mammograms, ultrasonography, computerized tomography (CT), positron emission tomography-computed tomography (PET-CT), and magnetic resonance imaging (MRI) of this rare disease. The various imaging findings of this lesion could be helpful for future diagnosis of male breast lesions.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.123-130
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• 2016

Purpose : The aim of this study was to compare the differences between the volumes acquired with four-dimensional computed tomography (4DCT)images with a reconstruction image-filtering algorithm and cone-beam computed tomography (CBCT) images with dynamic phantom. Materials and Methods : The 4DCT images were obtained from the computerized imaging reference systems (CIRS) phantom using a computed tomography (CT) simulator. We analyzed the volumes for maximum intensity projection (MIP), minimum intensity projection (MinIP) and average intensity projection (AVG) of the images obtained with the 4DCT scanner against those acquired from CBCT images with CT ranger tools. Results : Difference in volume for node of 1, 2 and 3 cm between CBCT and 4DCT was 0.54~2.33, 5.16~8.06, 9.03~20.11 ml in MIP, respectively, 0.00~1.48, 0.00~8.47, 1.42~24.85 ml in MinIP, respectively and 0.00~1.17, 0.00~2.19, 0.04~3.35 ml in AVG, respectively. Conclusion : After a comparative analysis of the volumes for each nodal size, it was apparent that the CBCT images were similar to the AVG images acquired using 4DCT.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.3
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• pp.81-87
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• 2021

PURPOSE: This study compared the cross-sectional areas (CSA) of the cervical muscles of straight neck patients and normal participants during a craniocervical flexion exercise (CCFE) using computerized tomography (CT) to investigate the effects of CCFE on the cervical curve. METHODS: Eighteen subjects were recruited for this study. Nine subjects were allocated to the straight neck group (subjects with pain and a cervical lordosis angle of less than 20°); the remainder formed the control group (subjects with a cervical lordosis angle greater than 20°). The CSA of the subjects' neck flexors (longus colli, longus capitis, and sternocleidomastoid) were measured by CT during rest and CCFE in the supine position, and the range of motion (ROM) of neck flexion was measured using a C-ROM instrument in a sitting. RESULTS: The straight neck group had a significantly smaller CSA of the longus colli, longus capitis, and sternocleidomastoid than the control group (p < .05). Both the straight neck and control groups showed statistically significant increases in the CSA of the neck flexors during CCFE compared to that at rest (p < .05). In addition, the straight neck group showed a significantly smaller ROM of neck flexion than the control group (p < .05). CONCLUSION: The results of this study provide more concrete evidence for therapists by demonstrating that CCFE improves the neck function by strengthening the neck flexors and increasing the neck stability for straight neck patients. Therefore, it is necessary to perform CCFE and neck extension exercises to rehabilitate straight neck patients.

• Journal of Biomedical Engineering Research
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• v.13 no.3
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• pp.217-224
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• 1992

A new three-channel surface gradient coil obtained by using numerical optimization and its application to MR computerized nomography are presented. The new surface gradient coil pro aided linear field gradient region more than twice wider compared with the t'irst surface gradi encl coil, removed torque and field offset, and reduced coupling between the surface gradient coil and combined surface rf coil. We realized the new surface gradient coil set with $30{\times}60{cm^2}$2 size, which generated more tharl 4G/cm with 100 amperes over a $4{\times}4{\times}4{cm^3}$ region with good linearity. The optimal geometries of the three-channel surface gradient coil and volun teer's high-resolution in wiuo spinal cord Images obtained by using the optimized surface gradi ent coil set are presented.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.4
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• pp.278-283
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• 2017

Purpose: The aim of this study was to evaluate the interdental distances of anterior, premolar, and molar teeth at the cementoenamel junction (CEJ) and 2 mm below the CEJ in healthy natural dentition with cone-beam computerized tomography (cone-beam CT) in order to provide valuable data for ideal implant positioning relative to mesiodistal bone dimensions. Materials and Methods: Two hundred patients who visited Dental Hospital, Wonkwang University, who had natural dentition with healthy interdental papillae, and who underwent cone-beam CT were selected. The cone-beam CT images were converted to digital imaging and communication in medicine (DICOM) files and reconstructed in three-dimensional images. To standardize the cone-beam CT images, head reorientation was performed. All of the measurements were determined on the reconstructed panoramic images by three professionally trained dentists. Results: At the CEJ, the mean maxillary interdental distances were 1.84 mm (anterior teeth), 2.07 mm (premolar), and 2.08 mm (molar), and the mean mandibular interproximal distances were 1.55 mm (anterior teeth), 2.20 mm (premolar), and 2.36 mm (molar). At 2mm below the CEJ, the mean maxillary interdental distances were 2.19 mm (anterior teeth), 2.51 mm (premolar), and 2.60 mm (molar), and the mean mandibular interproximal distances were 1.86 mm (anterior teeth), 2.53 mm (premolar), and 3.01 mm (molar). Conclusion: The interdental distances in the natural dentition were larger at the posterior teeth than at the anterior teeth and also at 2 mm below the CEJ level compared with at the CEJ level. The distances between mandibular incisors were the narrowest and the distances between mandibular molars were the widest in the entire dentition.