• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.199-206
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• 2003

Because the MIRD phantom, the representative mathematical phantom was developed for the calculation of internal radiation dose, and simulated by the simplified mathematical equations for rapid computation, the appropriateness of application to external dose calculation and the closeness to real human body should be justified. This study was intended to modify the MIRD phantom according to the comparison of the organ absorbed doses in the two phantoms exposed to monoenergetic broad parallel photon beams of the energy between 0.05 MeV and 10 MeV. The organ absorbed doses of the MIRD phantom and the Zubal yokel phantom were calculated for AP and PA geometries by MCNP4C, general-purpose Monte Carlo code. The MIRD phantom received higher doses than the Zubal phantom for both AP and PA geometries. Effective dose in PA geometry for 0.05 MeV photon beams showed the difference up to 50%. Anatomical axial views of the two phantoms revealed the thinner trunk thickness of the MIRD phantom than that of the Zubal phantom. To find out the optimal thickness of trunk, the difference of effective doses for 0.5 MeV photon beams for various trunk thickness of the MIRD phantom from 20 cm to 36 cm were compared. The optimal thunk thickness, 24 cm and 28 cm for AP and PA geometries, respectively, showed the minimum difference of effective doses between the two phantoms. The trunk model of the MIRD phantom was modified and the organ doses were recalculated using the modified MIRD phantom. The differences of effective dose for AP and PA geometries reduced to 7.3% and the overestimation of organ doses decreased, too. Because MIRD-type phantoms are easier to be adopted in Monte Carlo calculations and to standardize, the modifications of the MIRD phantom allow us to hold the advantage of MIRD-type phantoms over a voxel phantom and alleviate the anatomical difference and consequent disagreement in dose calculation.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.88-94
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• 2020

Purpose: The purpose of this study was to analyze the sagittal root position of maxillary anterior teeth and report the frequency of each classification in Korean for immediate implant placement. Materials and Methods: A retrospective review of cone-beam computed tomography (cone-beam CT) images was conducted on 120 patients (60 male and 60 female) who fulfilled the inclusion criteria. After reorientation of the axis, cone-beam CT images were evaluated and the relationship of the sagittal root position (SRP) of the maxillary anterior teeth to its associated osseous housing was recorded. Class I, II, and III were classified respectively when the root was positioned on the labial, central, and palatal aspect of the alveolar bone. Class IV was the position that at least two thirds of the root is engaging both the labial and palatal cortical plates. Then, the angulation of the root axis and the alveolar bone axis was measured. Descriptive statistics and Kruskal-Wallis test were used to compare the angulation according to the root position and SRP class. Results: The frequency distribution of sagittal root position of maxillary anterior teeth indicated that 81.1%, 10.3%, 1.9%, and 6.7% were classified as Class I, II, III, and IV, respectively. The sagittal angulation at approximately 77.5% of central incisor, lateral incisor, and canine was < 20 degrees, but the angle at more than 42.7% of canine was ≥ 20 degrees. Within the class, the angulation was statistically significantly greater in Class I (16.19) compared to Class II (8.72) and Class III (9.93), and smaller in Class IV (3.79). Conclusion: Within the limitation of this study, a majority of the maxillary anterior roots were positioned close to the buccal cortical plate. However, some roots have very thin alveolar bone and sagittal angulation larger than 30 degrees. Therefore, cone-beam CT analyses of the sagittal root position and the sagittal angulation are recommended for the selection of the appropriate dental implant treatment approach.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.1051-1062
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• 1997

Background : In asthma, airway obstruction is usually reversible, either spontaneously or with treatment. However, the responses to treatment are variable and some patients show an irreversible component of airflow obstruction. This may be associated with structural changes in the airway. To assess the relationship between the difference in airway reversibility and structural changes, we evaluated the HRCT findings and pulmonary function test. Methods : We studied 40 asthmatic subjects who had had acute exacerbation of symptoms and had showed normal chest X-ray findings. They had monitered PEFR daily, and had performed PFT and HRCT within three days after initiation of treatment. According to serial PEFR, they were grouped into 3 categories (Group 0 ; initial PEFR was within normal limit, Group 1 ; revealed increment of 30% in PEFR within 3 days after initiation of treatment, Group 2 ; revealed within 2 weeks) and then grouped again into 4 (Group 0, Group 3 ; reached to normal value of PEFR within 3 days after initiation of treatment, Group 4 ; within 2 weeks, Group 5 ; not within 2 weeks). Results : (1) Age in Group 0 was significantly lower than other groups(p<0.05), but there was no significance in other groups. (2) Duration of asthma in Group 2 was significantly longer than Group 0, 1(p<0.05). (3) FVC(%) and FEV1(%) were significantly decreased with delayed response to the treatment (p<0.05). (4) $FEV_1$/FVC(%) in Group 1, 2 were significantly lower than Group 0(p<0.05). $FEV_1$/FVC(%) in Group 5 was significantly lower than Group 0,3,4 (p<0.05). (5) Air trapping was increased significantly with delayed response to the treatment (p<0.05). (6) Mucus impaction in Group 0 was significantly larger than Group 1,2 (p<0.05). $FEV_1$/FVC(%) in Group 0,4,5 were significantly larger than Group 3 (p<0.05). Conclusion : Difference in reversibility of airway obstruction was associated with age, duration of asthma and severity of initial airflow obstruction There was no definite difference in HRCT findings in asthma.

• Tuberculosis and Respiratory Diseases
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• v.44 no.4
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• pp.766-775
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• 1997

Background : Primary malignant tumors of the trachea are extremely rare entities and account for a mere 0.1 per cent of all malignancies of the respiratory tract. Because of vague localizing signs, symptoms and a usually negative routine chest film, the patients with tracheal tumors are often treated for asthma or chronic obstructive pulmonary disease for considerable period of time before correct diagnosis. Method : We have made a review of the 17 cases of primary tracheal tumors in recent 15 years. We reviewed the clinical features including history of smoking and respiratory symptoms, the official readings of initial routine chest film, the cytologic examination of sputum, the time of delay in diagnosis, and the response according to the therapeutic modalities. Results : Eight out of 9 patients with squamous cell carcinoma(SCC) were above 50 years old, five out of 6 patients with adenoid cystic carcinoma(ACC) were below 50 years old. The most common location of primary tracheal tumors was the upper one-third of trachea in 8 cases(47%). The most frequent symptoms were dyspnea in 13/17 cases(76%) and then stridor or wheezing, cough. and sputum in order. The routine chest roentgenographic examinations were not helpful to diagnose tracheal carcinoma and the cytologic examinations of sputums were helpful to diagnose tracheal carcinoma in only one case with adenocarcinoma. The mean times of delay in diagnosis of patients with sec and ACC were 5 months and 24.9 months respectively. We had bronchial asthma in 8 cases(47%) and tracheal tumors in 4 cases(23%) as initial clinical impression. Conclusion : We would like to perform more comprehensive diagnostic tools(high KVP technique, the fibroptic bronchoscopic examination, chest CT scan etc.) in patients who had the suggestive points for the tracheal tumorse(1. unexplained hemoptysis or hoarsness, 2. inspiratory wheezing or stridor, 3. wax and waning of dyspnea according to changes of position, 4. progressive asthmatics unresponsive to antiasthmatic therapy) and radical resection of tumor or external radiation therapy with curative aim as possible.

• Tuberculosis and Respiratory Diseases
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• v.53 no.1
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• pp.27-35
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• 2002

Background : The paradoxical response refers to an enlargement of old lesions or unexpected new ones during apparently adequate antituberculous therapy. This response has been reported in cases of intracranial tuberculoma, tuberculous lymphadenopathy, tuberculous pleurisy and pulmonary tuberculosis. However, there are few reports on its frequency and clinical characteristics. Materials and Methods : This study enrolled 205 patients who were treated with first line antituberculous agents for more than 6 months. We retrospectively studied 155 patients with pulmonary tuberculosis and 57 patients with pleural tuberculosis (7 patients had both) from July 1998 to March 2000. The patients were divided into the paradoxical response group and the non-paradoxical group. The clinical characteristics of the paradoxical response group and the non-paradoxical group. The clinical characteristics of the paradoxical group were investigated. Statistical analysis was done with an independent sample T-test and Chi-squared test. Results : 29 of the 205 patients(14.1%) had paradoxical response. Among the 29 patients, there were 19 pulmonary tuberculosis, 8 tuberculous pleurisy(2 patients had both). Paradoxical response appeared 32 days (mean 35 days in pulmonary tuberculosis, mean 25 days in tuberculous pleurisy) after the beginning of chemotherapy. The duration to regress less than half of initial chest lesion was 114 days in pulmonary tuberculosis and 124 days in tuberculous pleurisy, respectively. Most common clinical manifestation of paradoxical response patients was coughing in both pulmonary tuberculosis and tuberculous pleurisy. Male sex, high blood WBC count and high level of pleural fluid LDH were related with paradoxical response. Conclusion : These findings suggest that presponse usually appears 1 month and disappears within 4 months after the beginning of anti-tuberculous chemotherapy. Paradoxical response was relatively correlated with male sex, high blood WBC count and high level of pleural fluid LDH.

• The korean journal of orthodontics
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• v.29 no.6 s.77
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• pp.707-720
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• 1999

The purpose of this study was to evaluate racial differences In head posture and the influence of head posture to the craniofacial morphology. The sample group of this study was made up of 51 Korean males and 120 Scandinavian Caucasian males. From the comparison of the cranio-cervical angle and the variables of craniofacial morphology between them, the following results were obtained. 1. The cranio-cervical angle (NSL/OPT) was on average 9.28 degrees larger In Koreans. 2. The length of the anterior cranial base (N-S) was on average 4.66mm shorter in Koreans. 3. The length of the maxillary base (sp-pm and ss-pm) were on average 2.75mm and 4.65mm shorter in Koreans respectively, the anterior maxillary height (n-sp) was on average 2.60mm longer, the posterior dimension (s-pm) was found to be 2.06mm longer in Koreans, and the maxillary inclination (NSL/NL) was identical in both samples. 4. The mandibular body length (pg-tgo) and ramus height (ar-tgo) were identical in the two groups, but the genial angle (ML/RL) was 3.22 degrees smaller and the mandibular plane inclination (NSL/ML) was 2.44 degrees larger in Koreans 5. The maxillary prognathism (s-n-sp and s-n-ss) and the mandibular prognathism (s-n-sm) were identical in both samples. 6. The sagittal jaw relationship (ss-n-pg) was 1.44 degrees larger in the Korean sample, but the vortical jaw relationship (NL/ML) was not significantly different. 7. The anterior facial height (n-gn) was 5.57mm longer in the Korean sample. 8. The mandibular alveolar prognathism (CL/ML) was 5.71 degrees greater and the interincisal angle (ILs/ILi) was 3.08 degrees more acute in Koreans. Taken together these results, craniofacial morphology can be influenced by the head posture defined by cranio-cervical angulation.

• Journal of Internet Computing and Services
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• v.17 no.1
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• pp.101-107
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• 2016

Due to the recent advancement in digital imaging technology, development of intervention equipment has become generalize. Video arbitration procedure is a process to insert a tiny catheter and a guide wire in the body, so in order to enhance the effectiveness and safety of this treatment, the high-quality of x-ray of image should be used. However, the increasing of radiation has become the problem. Therefore, the studies to improve the performance of x-ray detectors are being actively processed. Moreover, this intervention is based on the reference of the angiographic imaging and 3D medical image processing. In this paper, we propose a guidance system to support this intervention. Through this intervention, it can solve the problem of the existing 2D medical images based vessel that has a formation of cerebrovascular disease, and guide the real-time tracking and optimal route to the target lesion by intervention catheter and guide wire tool. As a result, the system was completely composed for medical image acquisition unit and image processing unit as well as a display device. The experimental environment, guide services which are provided by the proposed system Brain Phantom (complete intracranial model with aneurysms, ref H+N-S-A-010) was taken with x-ray and testing. To generate a reference image based on the Laplacian algorithm for the image processing which derived from the cerebral blood vessel model was applied to DICOM by Volume ray casting technique. $A^*$ algorithm was used to provide the catheter with a guide wire tracking path. Finally, the result does show the location of the catheter and guide wire providing in the proposed system especially, it is expected to provide a useful guide for future intervention service.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.33-38
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• 2014

Purpose Auto exposure control (AEC) in SPECT/CT automatically controls the exposure dose (mA) according to patient's shape and size. The aim of this study was to evaluate the effect of AEC in SPECT/CT on exposure dose reduction and image quality. Materials and Methods The model of SPECT/CT used in this study was Discovery 670 (GE, USA), Smart mA for AEC; and $^{99m}Tc$ as a radioisotope. To compare SPECT and CT images by CT exposure dose variation, we used a standard technique set at 80, 100, 120, 140 kVp, 10, 30, 50, 100, 150, 200, 250 mA, and AEC at 80, 100, 120, 140 kVp, 10-250 mA. To evaluate resolution and contrast of SPECT images, triple line phantom and flangeless Esser PET phantom were used. For CT images, noise and uniformity were checked by anthropomrphic chest phantom. For dose evaluation to find DLP value, anthropomorphic chest phantom was used and the CT protocol of torso was applied by standard technique (120 kVp, 100 mA) and AEC (120 kVp, 10-250 mA). Results When standard and AEC were applied, the resolutions at SPECT images with attenuation correction (AC) were the same as FWHM by center 3.65 mm, left 3.48 mm, right 3.61 mm. Contrasts of standard and AEC showed no significant difference: standard 53.5, 29.8, 22.5, 15.8, 6.0, AEC 53.5, 29.6, 22.4, 15.7, 6.1 In CT images, noise values at standard and AEC were 15.4 and 18.5 respectively. The application of AEC increases noise but the value of coefficient variation were 33.8, 24.9 respectively, obtaining uniform noise image. The values of DLP at standard and AEC were 426.78 and 352.09 each, which shows that the application of AEC decreases exposure dose more than standard by approximately 18%. Conclusion The results of our study show that there was no difference of AC in SPECT images based on the CT exposure dose variation at SPECT/CT images. It was found that the increased CT exposure dose leads to the improvement of CT image quality but also increases the exposure dose. Thus, the use of AEC in SPECT/CT contributes to obtaining equal AC SPECT images, and uniform noise in CT images while reducing exposure dose.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.12 no.1
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• pp.10-15
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• 2009

Purpose: The manner of rectal bleeding of auto-amputated polyps (AP) is similar to juvenile polyps (JP) or Meckel's diverticula (MD). We conducted this study to characterize the clinical spectrum of AP. Methods: Fourteen patients were enrolled this study who were diagnosed AP due to painless rectal bleeding. The clinical data of AP was assessed and then compared with the clinical data of JP and MD retrospectively. Results: The prevalence of AP was 10.4% (14/135) and high in younger patients compared with that of JP (p=0.042 below 2 years). Whereas JP was more common in patients aged 2 to 5 years (p=0.005). Male was predominant in AP (p=0.008 AP vs JP). The manner of rectal bleeding in AP group was sudden and transient. There was no significant difference in time interval between onset of rectal bleeding and diagnosis between the 3 groups. However AP was diagnosed in 9 patients (64.3%) within 7 days after onset of rectal bleeding, but JP was diagnosed in 5 patients (4.1%) in the same period (p<0.001). All of AP were located in the rectum and the sigmoid colon. The mean hemoglobin was 11.3${\pm}$1.5 g/dL in AP, 11.8${\pm}$1.3 g/dL in JP, and 8.4${\pm}$1.2 g/dL in MD (p<0.001, only significant in MD). Conclusion: AP may be considered in male older than 1 year with transient and sudden onset or increase of painless rectal bleeding without drop of hemoglobin level.

• Pediatric Infection and Vaccine
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• v.12 no.2
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• pp.149-156
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• 2005

Purpose : Acute septic arthritis and acute osteomyelitis are not rare diseases in pediatric population. But when the diagnosis is delayed or inappropriate treatments are given, permanent disabilities of joint or bone can be followed. We analysed clinical manifestations, laboratory findings, X-ray findings, causative microorganisms and antibiotic susceptibility results of the two diseases in children. Methods : During January 1992 and May 2002, we conducted a retrospective study of 103 children who were diagnosed as acute septic arthritis and acute osteomyelitis. We selected out 34 children who had positive culture results in the blood or involved sites. Results : 19 cases were diagnosed as acute septic arthritis and 15 cases were acute osteomyelitis. These diseases were most common in preschool children and next in neonates. Hip joints and tibia were the most common sites in each disease. X-ray findings showed abnormalities in 6 cases(36%) of acute septic arthritis and 7 cases(50%) of acute osteomyelitis on admission. The most common microorganism isolated from the involved sites was Staphylococcus aureus; 12 out of 14 cases in acute septic arthritis and 6 out of 13 cases in acute osteomyelitis. Conclusion : It is difficult to make a clear initial diagnosis of the two diseases. We could not find any differences between these two diseases on clinical manifestations such as fever, swelling, tenderness and limitation of movements in joint and bone. The most common microorganism was Staphylococcus aureus.