PURPOSE: NEMA NU2-2001 was proposed as a new standard for performance evaluation of whole body PET scanners. In this study, system performance of Siemens CTI ECAT EXACT 47 PET scanner including spatial resolution, sensitivity, scatter fraction, and count rate performance in 2D and 3D mode was evaluated using this new standard method. METHODS: ECAT EXACT 47 is a BGO crystal based PET scanner and covers an axial field of view (FOV) of 16.2 cm. Retractable septa allow 2D and 3D data acquisition. All the PET data were acquired according to the NEMA NU2-2001 protocols (coincidence window: 12 ns, energy window: 250 ~ 650 keV). For the spatial resolution measurement, F-18 point source was placed at the center of the axial FOV ( (a) x=0, and y=1, (b) x=0, and y=10, (c) x=10, and y=0cm) and a position one fourth of the axial FOV from the center ( (a) x=0, and y=1, (b) x=0, and y=10, (c) x=10, and y=0cm). In this case, x and y are transaxial horizontal and vertical, and z is the scanner's axial direction. Images were reconstructed using FBP with ramp filter without any post-processing. To measure the system sensitivity, NEMA sensitivity phantom filled with F-18 solution and surrounded by 1~5 aluminum sleeves were scanned at the center of transaxial FOV and 10 cm offset from the center. Attenuation free values of sensitivity were estimated by extrapolating data to the zero wall thickness. NEMA scatter phantom with length of 70 cm was filled with F-18 or C-11solution (2D: 2, 900 MBq, 3D: 407 MBq), and coincidence count rates were measured for 7 half-lives to obtain noise equivalent count rate (NECR) and scatter fraction. We confirmed that dead time loss of the last frame were below 1%. Scatter fraction was estimated by averaging the true to background (scatter + random) ratios of last 3 frames in which the fractions of random rate are negligibly small. RESULTS: Axial and transverse resolutions at 1cm offset from the center were 0.62 and 0.66 cm (FBP in 2D and 3D), and 0.67 and 0.69 cm (FBP in 2D and 3D). Axial, transverse radial, and transverse tangential resolutions at 10cm offset from the center were 0.72 and 0.68 cm (FBP in 2D and 3D), 0.63 and 0.66 cm (FBP in 2D and 3D), and 0.72 and 0.66 cm (FBP in 2D and 3D). Sensitivity values were 708.6 (2D), 2931.3 (3D) counts/sec/MBq at the center and 728.7 (2D), 3398.2 (3D) counts/sec/MBq at 10 cm offset from the center. Scatter fractions were 0.19 (2D) and 0.49 (3D). Peak true count rate and NECR were 64.0 kcps at 40.1 kBq/mL and 49.6 kcps at 40.1 kBq/mL in 2D and 53.7 kcps at 4.76 kBq/mL and 26.4 kcps at 4.47 kBq/mL in 3D. CONCLUSION: Information about the performance of CTI ECAT EXACT 47 PET scanner reported in this study will be useful for the quantitative analysis of data and determination of optimal image acquisition protocols using this widely used scanner for clinical and research purposes.
Aluminum ; Architectural Accessibility ; Noise

OBJECTIVES: The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). MATERIALS AND METHODS: The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. RESULTS: Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. CONCLUSIONS: Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.
Architectural Accessibility ; Constriction ; Electric Impedance* ; Endodontics

OBJECTIVES: The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). MATERIALS AND METHODS: The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. RESULTS: Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. CONCLUSIONS: Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.
Architectural Accessibility ; Constriction ; Electric Impedance* ; Endodontics

PURPOSE: Philips GEMINI is a newly introduced whole-body GSO PET/CT scanner. In this study, performance of the scanner including spatial resolution, sensitivity, scatter fraction, noise equivalent count ratio (NECR) was measured utilizing NEMA NU2-2001 standard protocol and compared with performance of LSO, BGO crystal scanner. METHODS: GEMINI is composed of the Philips ALLEGRO PET and MX8000 D multi-slice CT scanners. The PET scanner has 28 detector segments which have an array of 29 by 22 GSO crystals (4x6x20 mm), covering axial FOV of 18 cm. PET data to measure spatial resolution, sensitivity, scatter fraction, and NECR were acquired in 3D mode according to the NEMA NU2 protocols (coincidence window: 8 ns, energy window: 409~664 keV). For the measurement of spatial resolution, images were reconstructed with FBP using ramp filter and an iterative reconstruction algorithm, 3D RAMLA. Data for sensitivity measurement were acquired using NEMA sensitivity phantom filled with F-18 solution and surrounded by 1~5 aluminum sleeves after we confirmed that dead time loss did not exceed 1%. To measure NECR and scatter fraction, 1110 MBq of F-18 solution was injected into a NEMA scatter phantom with a length of 70 cm and dynamic scan with 20-min frame duration was acquired for 7 half-lives. Oblique sinograms were collapsed into transaxial slices using single slice rebinning method, and true to background (scatter + random) ratio for each slice and frame was estimated. Scatter fraction was determined by averaging the true to background ratio of last 3 frames in which the dead time loss was below 1%. RESULTS: Transverse and axial resolutions at 1cm radius were (1) 5.3 and 6.5 mm (FBP), (2) 5.1 and 5.9 mm (3D RAMLA). Transverse radial, transverse tangential, and axial resolution at 10 cm were (1) 5.7, 5.7, and 7.0 mm (FBP), (2) 5.4, 5.4, and 6.4 mm (3D RAMLA). Attenuation free values of sensitivity were 3, 620 counts/sec/MBq at the center of transaxial FOV and 4, 324 counts/sec/MBq at 10 cm offset from the center. Scatter fraction was 40.6%, and peak true count rate and NECR were 88.9 kcps @ 12.9 kBq/mL and 34.3 kcps @ 8.84 kBq/mL. These characteristics are better than that of ECAT EXACT PET scanner with BGO crystal. CONCLUSION: The results of this field test demonstrate high resolution, sensitivity and count rate performance of the 3D PET/CT scanner with GSO crystal. The data provided here will be useful for the comparative study with other 3D PET/CT scanners using BGO or LSO crystals.
Aluminum ; Architectural Accessibility ; Noise ; Positron-Emission Tomography and Computed Tomography* ; Radius

Mechanical properties and microleakage of two composites [conventional hybrid type DenFil (VERICOM Co., Anyang, Korea) / micro matrix hybrid type Esthet X (Dentsply Caulk, Milford, DE, U.S.A.)] were evaluated to assess whether variable light intensity curing is better than conventional curing technique. Curing was done for 40 seconds in two ways of 2 step soft-start technique and 5 step ramping technique. Three kinds of light intensities of 50, 100, 200 mW/cm2 were initially used for 10, 20, 30 seconds each and the maximum intensity of 600 mW/cm2 was used for the rest of curing time in a soft-start curing technique. In a ramping technique, curing was done with the same initial intensities and the light intensity was increased 5 times with the same rate to the maximum intensity of 600 mW/cm2. After determining conditions that showed no different mechanical properties with conventional technique, Esthet X composite was filled in a class V cavity, which dimension was 4x3x1.5 mm and cured under those conditions. Microleakage was evaluated in two ways of dye penetration and maximum gap estimation through SEM observation. ANOVA and Spearman's rho test were used to confirm any statistical significance among groups. The results were as follows: 1. Several curing conditions of variable light intensities resulted in the similar mechanical properties with a conventional continuous curing technique, except conditions that start curing with an initial light intensity of 50 mW/cm2, 2. Conventional and ramping techniques were better than soft-start technique in mechanical properties of microhardness and compressive strength. 3. Soft-start group that started curing with an initial light intensity of 100 mW/cm2 for 10 seconds showed the least dye penetration. Soft-start group that started curing with an initial light intensity of 200 mW/cm2 for 10 seconds showed the smallest marginal gap, if there was no difference among groups. 4. Soft-start technique resulted in better dye-proof margin than conventional technique (p=0.014) and ramping technique(p=0.002). 5. There was a very low relationship(p=0.157) between the methods of dye penetration and marginal gap determination through SEM evaluation. From the results of this study, it was revealed that ramping technique would be better than conventional technique in mechanical properties, however, soft-start technique might be better than conventional one in microleakage. It was concluded that much endeavor should be made to find out the curing conditions, which have advantages of both aspects or to solve these kinds of problems through a novel idea of polymerization.
Architectural Accessibility ; Compressive Strength ; Gyeonggi-do ; Polymerization ; Polymers

PURPOSE: This study examined two trunk strategies - medio-lateral ramp and anterior-posterior ram - and their effects on pelvis and trunk movements, providing basic material for safe ramp utilization. METHODS: The present study included 20 asymptomatic males recruited from a local university. Participants were asked to stand with their feet shoulder-width apart. Their dorsal side faced the camera, and measurements were performed while standing in a neutral double stance, one leg stance, 15° of medial and lateral ramp, and 15° of anterior and posterior ramp. Participants were allowed to practice for 3 minutes, and each participant had a 30 seconds rest between the two ramp conditions. One-way repeated measures analysis of variance was used to determine the effects the ramp conditions on spinal alignment. In all analyses, p<0.05 was used to indicate statistical significance. RESULTS: The trunk-inclination angle on the posterior ramp was significantly lower than that of the double stance position (p<0.05). The trunk imbalance angle was significantly higher on the medial ramp, than that on the double stance position (p<0.05). The pelvic position and pelvic torsion angles were significantly higher in the medial, lateral, and anterior ramp positions than that of the double stance position (p<0.05). The pelvic rotation angles on the medial, lateral, and anterior ramps were significantly lower than that of the double stance position (p<0.05). CONCLUSION: These findings suggest that when people are exposed to the same form of ramp for an extended period, posture modifications may be triggered.
Architectural Accessibility* ; Foot ; Humans ; Leg ; Male ; Pelvis ; Posture

The intestine is a unique organ inhabited by a tremendous number of microorganisms. Intestinal epithelial cells greatly contribute to the maintenance of the symbiotic relationship between gut microbiota and the host by constructing mucosal barriers, secreting various immunological mediators and delivering bacterial antigens. Mucosal barriers, including physical barriers and chemical barriers, spatially segregate gut microbiota and the host immune system to avoid unnecessary immune responses to gut microbes, leading to the intestinal inflammation. In addition, various immunological mediators, including cytokines and chemokines, secreted from intestinal epithelial cells stimulated by gut microbiota modulate host immune responses, maintaining a well-balanced relationship between gut microbes and the host immune system. Therefore, impairment of the innate immune functions of intestinal epithelial cells is associated with intestinal inflammation.
Antigens, Bacterial ; Architectural Accessibility ; Chemokines ; Cytokines ; Epithelial Cells* ; Gastrointestinal Microbiome ; Homeostasis* ; Immune System ; Inflammation ; Intestines

BACKGROUND: Optimal head and neck positioning and clinical experience are important factors for successful endotracheal intubation in patients with a difficult airway. This study aimed to investigate the rate of successful endotracheal intubation between the sniffing and ramped positions in patients with an expected difficult intubation. METHODS: The study included 204 patients with an expected difficult intubation (airway difficulty score > or = 8) based on the preoperative airway assessment. The patients were randomized into the following groups: group S was placed in the sniffing position, and group R was placed in the ramped position during direct laryngoscopy. The primary outcome was successful endotracheal intubation and the secondary measure was laryngeal view in the ramped or sniffing position when the operating table was placed at two different heights. RESULTS: Group R showed a higher rate of successful endotracheal intubation and better laryngeal view than group S (P < 0.05). The rate of successful endotracheal intubation was higher in group R than in group S at both heights of the operating table; but, it was not different within each group. Laryngeal view was not different between the two groups and within each group when the two heights of the operating table were used. Fully trained and experienced attending anesthesiologists achieved a higher rate of successful endotracheal intubation than less experienced residents in group R (P < 0.05) but not in group S. CONCLUSIONS: Ramped position and clinical experience can be important factors for laryngeal view and success rate of endotracheal intubation in patients with an expected difficult intubation.
Architectural Accessibility ; Head ; Humans ; Intubation* ; Intubation, Intratracheal* ; Laryngoscopy ; Neck ; Operating Tables ; Prospective Studies*

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin. VIP(TM) (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501(TM) (Demetron/Kerr, Danbury, CT, USA) were used for curing Filtek(TM) Z-250 (3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP(TM) (Bisco) 200mW/cm2 (V2), 400mW/cm2 (V4), 600mW/cm2 (V6), Pulse-delay (200 mW/cm2 3 seconds, 5 minutes wait, 600mW/cm2 30seconds, VPD) and Optilux 501(TM) (Demetron/Kerr) C-mode (OC), R-mode (OR). Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each). Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens. V2, V4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and OR, VPD groups were measured in the above mentioned irradiation modes (n=5, each). Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each). For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes: V2/60 seconds, V4/40 seconds, V6/30 seconds, VPD, OC and OR. Microleakage was assessed by dye penetration along enamel and dentin margins of cavities. Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chi-square test for microleakage values. The results were as follows: 1. Polymerization shrinkage was increased with higher light intensity in groups using VIP(TM) (Bisco): the highest with 600mW/cm2, followed by Pulse-delay, 400mW/cm2 and 200mW/cm2 groups. The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501(TM) (Demetron/Kerr). 2. Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.30. 3. Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP(TM) (Bisco). The micoleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501(TM)(Demetron/Kerr) was used.
Architectural Accessibility ; Dental Enamel ; Dentin ; Humans ; Light ; Molar, Third ; Polymerization ; Polymers ; Spectroscopy, Fourier Transform Infrared ; Tokyo

This study was to investigate the various parts of the mandible related to inferior alveolar nerve conductive anesthesia in 228 dry skulls of Korean adults. Five morphological variations were observed and four measurements were undertaken. The following results were obtained. 1. The Position of coronoid notch in the anterior border of the ramus of mandible is classified into three types and percentage of each type was as follows : Type I (Coronoid notch in the middle part of the anterior border of the ramus of mandible) : 83.3% Type II (Coronoid notch in the inferior part of the anterior border of the ramus of mandible) : 12.7% Type III (No coronoid notch in the anterior border of the ramps of mandible) : 4.0% 2. The position of the lingula of mandible to the imaginary line of the molar occlusal plane is classified into three types and percentage of each type was as follows : Type I (Above the imaginary line of the mandibular molar occlusal plane) : 87.3% Type II (Coincide with the imaginary line of the mandibular molar occlusal plane) : 8.6% Type III (Below the imaginary of mandibular molar occlusal plane) : 4.3% 3. The position of the lingula of the mandible in the internal oblique line-posterior border of the ramus of mandible dimension is classified into three types and percentage of each type was as follows : Type I (Anterior part in the internal oblique line-posterior border of the ramus of mandible dimension) : 82.9% Type II (Middle part in the internal oblique line-posterior border of the ramus of mandible dimension) : 11. 4% Type III (Posterior part in the internal oblique line-posterior border of the ramus of mandible dimension) : 5.7% 4. The position of the apex of the lingula of mandible to the deepest point of the coronoid notch in the anterior border of the ramus of mandible is classified into three types and percentage of each type was as follows : Type I (Coincide with the deepest point of the coronoid notch) : 82.0% Type II (Above the deepest point of the coronoid notch) : 13.2% Type III (Below the deepest point of the coronoid notch) : 4.8% 5. The position of the apex of the lingula of mandible to the imaginary line of the mandibular molar occlusal plane is classified into three types and percentage of each type was as follows : Type I (Above the 8mm) : 65.7% Type II (Above the 5mm) : 18.6% Type III (Above the 10mm) : 15.7% 6. Angle between the line connecting the apex of the lingula of mandible-1-2 premolars in the contralateral side and median line of the mandible is classified into three types and percentage of each type was as follows : Type I (50°) : 67.2% Type II (45°) 21.4% Type III (55°) : 11.4% 7. The averages of the measurement of the various bony landmarks of the mandible related to inferior alveolar nerve conductive anesthesia were as follows : ① Distance from deepest point of the coronoid notch to internal oblique line : 9.2mm ② Distance from internal oblique line to the apex of the lingula of mandible : 11.6mm ③ Distance from deepest point of the coronoid notch to apex of the lingula of mandible : 19.7mm ④ Height of the lingula of mandible : 9.8mm
Adult ; Anesthesia* ; Architectural Accessibility ; Bicuspid ; Dental Occlusion ; Humans ; Mandible* ; Mandibular Nerve* ; Molar ; Skull