• Archives of Craniofacial Surgery
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• v.20 no.6
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• pp.370-375
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• 2019

Background: Some parts of a maxillary fracture-for example, the medial and posterior walls-may remain unreduced because they are unapproachable or hard to deal with. This study aimed to investigate the self-healing process of unreduced maxillary membranous parts of fractures through a longitudinal computed tomography (CT) analysis of cases of unilateral facial bone injuries involving the maxillary sinus walls. Methods: Thirty-two patients who had undergone unilateral facial bone reduction surgery involving the maxillary sinus walls without reduction of the medial and posterior walls were analyzed in this retrospective chart review. Preoperative, immediate postoperative, and 3-month postoperative CT scans were analyzed. The maxillary sinus volume was calculated and improvements in bone continuity and alignment were evaluated. Results: The volume of the traumatized maxillary sinuses increased after surgery, and expanded significantly by 3 months postoperatively (p< 0.05). The significant preoperative volume difference between the normal and traumatized sides (p= 0.024) resolved after surgery (p> 0.05), and this resolution was maintained at 3 months postoperatively (p > 0.05). The unreduced parts of the maxillary bone showed improved alignment and continuity (in 75.0% and 90.6% of cases, respectively), and improvements in bone alignment and bone continuity were found to be correlated using the Pearson chi-square test (p= 0.002). Conclusion: Maxillary wall remodeling through self-healing occurred concomitantly with an increase in sinus volume and simultaneous improvements in bone alignment and continuity. Midfacial surgeons should be aware of the natural course of unreduced fractured medial and posterior maxillary walls in complex maxillary fractures.

• Journal of IKEEE
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• v.19 no.1
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• pp.33-40
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• 2015

Inverse problem in electrical impedance tomography (EIT) is highly ill-posed therefore prior information is used to mitigate the ill-posedness. Regularization methods are often adopted in solving EIT inverse problem to have satisfactory reconstruction performance. In solving the EIT inverse problem, iterative Gauss-Newton method is generally used due to its accuracy and fast convergence. However, its performance is still suboptimal and mainly depends on the selection of regularization parameter. Although, there are few methods available to determine the regularization parameter such as L-curve method they are sometimes not applicable for all cases. Moreover, regularization parameter is a scalar and it is fixed during iteration process. Therefore, in this paper, a novel method is used to determine the regularization parameter to improve reconstruction performance. Conductivity norm is calculated at each iteration step and it used to obtain the regularization parameter which is a diagonal matrix in this case. The proposed method is applied to human thorax imaging and the reconstruction performance is compared with traditional methods. From numerical results, improved performance of proposed method is seen as compared to conventional methods.

• Korean Journal of Biological Psychiatry
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• v.17 no.3
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• pp.127-135
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• 2010

Objectives : This study was conducted to compare between hallucination group and delusion group in patient with schizophrenia, using Brain $^{99m}Tc$-ECD PECT. Methods : Among 16 patients with less than 3 schizophrenic episodes, 8 patients whose initial symptom was hallucination were assigned to the hallucination group, and other 8 patients with initial sumptom of delusion were assinged to the hallucination group. All of the patients clinically evaluated using the PANSS and BPRS. Both groups of patients and 8 healthy subjects underwent $^{99m}Tc$-ECD PECT. Results : Score of thinking disturbance subscale of BPRS were significantly lower in the hallucination group than the delusion group. In SPECT analysis, the hallucination group showed significantly increased perfusion in some areas of the right temporal lobe, bilateral limbic lobes and left parietal lobe compared to delusion group. Both group had a reduced rCBF in some areas of the frontal lobe. Conclusion : The hallucniation group, compared with the delusion group, showed significantly increased regional cerebral blood flow in some regions. Therefore, this data suggests that different neural substrates may affect the process of auditory hallucination and delusion.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.313-326
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• 2007

With rising prevalency of mouth breathing children caused by developing civilization and increasing pollution, there are many maxillary transverse discrepancy patients with undergrowth of maxilla. For improving this, maxillary mid-palatal suture splitting was often performed. The purpose of this study was to analyse the stress distribution on the craniofacial suture and cranium after rapid maxillary expansion by finite element model. The boy(13Y6M) was chosen for taking computed-tomography for finite element model. Three-dimensional model of maxilla, first premolar, first molar, buccal and lingual part of rapid maxillary expansion were constructed. 1. The alveolar bone adjacent to the first molar and the first premolar that was affected directly by rapid maxillary expansion was displaced laterally approximately 4.04mm at maximum. The force decreased toward anterior region and frontal alveolar bone displaced laterally about 3.18mm. 2. A forward maximum displacement was exhibited at zygomatic process middle region. 3. At maximum, maxillary median part experienced 0.973mm downward repositioning and 0.65mm upward repositioning at lateral alveolar bone. 4. Von mises stress was observed the largest stress distribution around teeth and zygomatic buttress. 5. The largest tensile force was observed around alveolar bone of teeth, while compression force was observed at zygomatic buttress.

• Conservation Science in Museum
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• v.7
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• pp.25-31
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• 2006

We performed the conservation treatment for Bigyeokchinjeonnoe (A kind of time bomb in the Joseon Dynasty) excavated from Hwawangsanseong Fortress in Changnyeong-gun, Gyeongsangnam-do Province. Part of the Bigyeokchinjeonnoe has been lost; we did not restore the lost part so that one can observe the inside through it. The results of X-ray investigation and C. T (Computed Tomography) scan proved the generation of many blowholes around the molding line during the casting process; a hole in the casting mold to maintain inner mold during casting was identified on the surface and traces of fortifying this part with iron plate were also identified. The main ingredients of the blue corrosion on the surface were identified as O, Fe, P, Si and Al by SEM/EDS analysis. The result of XRD analysis identified the blue corrosion as vivianite [Fe₃(PO₄)₂·8H₂O]. The metal structure clarified its material was gray cast iron.

• Polymer(Korea)
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• v.37 no.5
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• pp.563-570
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• 2013

Poly(vinyl pivalate) (PVPi) was bulk polymerized to make poly(vinyl alcohol) (PVA) microfibrils to apply for polymeric embolization coils replacing metalic coils. Then, syndiotactic PVA (s-PVA) microfibrils having number-average degree of polymerization of 1100 and s-diad content of 60.4% were prepared via saponification of the PVPi with no separate spinning process. To make s-PVA microfibrils with radiopacity, zirconium dioxide ($ZrO_2$) and barium sulfate ($BaSO_4$) were added into s-PVA microfibrils during saponification. The computed tomography (CT) value indicating radiopacity reached up to over 1000 when the amount of $ZrO_2$ and $BaSO_4$ were 12 and 6 wt%, respectively.

• Journal of radiological science and technology
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• v.43 no.2
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• pp.71-77
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• 2020

This study aims to explain the process of providing important medical images for the diagnosis of pneumonia caused by coronavirus disease 2019 (COVID-19) through the only mobile hospital computed tomography (CT) in Korea. Since January 28, 2020, medical imaging examinations have been provided to confirmed and suspected COVID-19 patients, and the quality of images was evaluated based on the objective and subjective indicators. In order to prevent the transmission in the hospital that may occur due to exposure to medical staff and general patients, personal protective equipment was worn and the separate route was used blocking human infection factors. For 11 weeks, a total of 185 tests were performed for 98 confirmed patients and 72 suspected patients. The average time to complete the test was 33 minutes. In the course of the test, no cross-infection cases were examined. During the outbreak of the COVID-19, the only mobile hospital CT room of Korea provided medical imaging examinations without infection among medical staff and patients and also provided adequate medical images without significant difference (p >0.05) in determining the degree of pneumonia progression compared to a stationary in-hospital CT.

• Journal of Korean Neurosurgical Society
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• v.38 no.3
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• pp.202-205
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• 2005

Objective : The purpose of this study is to measure the dimensions of foramen ovale and to localize the zygomatic point using computed tomography[CT] in Korean adults with idiopathic trigeminal neuralgia. Methods : Facial axial CT scans using the orbitomeatal plane were performed in 67patients [39males and 28females; mean age 58.8years] with idiopathic classic trigeminal neuralgia. We measured the size of the foramen ovale and localized the zygomatic point which was a skin marker over the ipsilateral zygoma that approximates the lateral projection of a straight line joining the centers of the two foramen ovale. Results : The axial dimensions of the foramen ovale on the orbitomeatal plane were of average length : $8.18{\pm}0.82mm$ [range $6.9{\sim}11.5mm$]. width : $4.06{\pm}0.86mm$ [$2.5{\sim}5.7mm$]. The average distance between the external acoustic meatus and the zygomatic point was $21.64{\pm}1.99mm$ [$16.3{\sim}25.0mm$] and the average distance of anterior margin of condylar process of mandible to zygomatic point was $4.29{\pm}1.19mm$ [$1.0{\sim}7.0mm$]. Conclusion : The anatomical understandings including the size of the foramen ovale and localization of the zygomatic point could be helpful in determining a plan of percutaneous approaches to foramen ovale.

• Journal of Korean Neurosurgical Society
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• v.37 no.5
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• pp.336-339
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• 2005

Objective: The goal of this study is to establish the anatomical criteria of the normal and stenotic lumbosacral extraforaminal tunnel, and also to determine the effect of the pathologic intervertebral disc on the size of extraforaminal tunnel in the lumbosacral spine. Methods: MRI and CT scans were reviewed and classified into two groups: (1) 40 patients with normal discs at L5- S1 (Group 1) and (2) 43 patients that had undergone successful decompression surgery for extraforaminal entrapment at the lumbosacral region(Group 2). In these two groups, the following parameters were compared are compared: the distance between the disc margin and the ala (lumbosacral tunnel) on the axial MRI, and the posterior disc height at L5-S1 on the mid-sagittal MRI. Results: In the group 1, the mean distance of the lumbosacral tunnel on the axial MRI was $10.1{\pm}2.2mm$. The mean posterior disc height at L5-S1 was $7.4{\pm}1.7mm$ on the mid-sagittal MRI. In the group 2, the mean distance between the disc margin and the ala (costal process) was $1.6{\pm}1.3mm$ on the axial MRI. The average posterior disc height was $4.4{\pm}1.5mm$ on the mid-sagittal MRI. The posterior disc height and the size of the lumbosacral tunnel between the two groups were statistically different on the paired t-test (p<0.0001). However, the posterior disc height was not positively correlated with the size of the extraforaminal tunnel for group 2 (p=0.909). Conclusion: The extraforaminal stenosis was correlated to pathologic disc. However, the posterior disc height was not correlated to the size of the of the extraforaminal tunnel.

• Journal of radiological science and technology
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• v.44 no.5
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• pp.473-480
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• 2021

This study was purpose to method that applies for improving the image quality in CT and X-ray scan, especially in the lung region. Also, we researched the parameters of the image before and after applying for Histogram Equalization (HE) such as mean, median values in the histogram. These techniques are mainly used for all type of medical images such as for Chest X-ray, Low-Dose Computed Tomography (CT). These are also used to intensify tiny anatomies like vessels, lung nodules, airways and pulmonary fissures. The proposed techniques consist of two main steps using the MATLAB software (R2021a). First, the technique should apply for the process of normalization for improving the basic image more correctly. In the next, the technique actively rearranges the intensity of the image contrast. Second, the Contrast Limited Adaptive Histogram Equalization (CLAHE) method was used for enhancing small details, textures and local contrast of the image. As a result, this paper shows the modern and improved techniques of HE and some advantages of the technique on the traditional HE. Therefore, this paper concludes that various techniques related to the HE can be helpful for many processes, especially image pre-processing for Machine Learning (ML), Deep Learning (DL).