• The korean journal of orthodontics
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• v.34 no.6 s.107
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• pp.497-505
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• 2004

The purpose of this study was to evaluate the post-retention stability of the lower incisor axis in Class II division 2 malocclusions. The dental casts and lateral cephalograms from before (T1) and after (T2) orthodontic treatment and long-term post-retention (T3) in 62 Class II division 2 malocclusion cases were included in this study. After several linear and angular measurements at each time were taken, the significance in the amount of change of the lower incisor axis for each gender and extraction versus non-extraction was evaluated. The results showed that the lower incisors that inclined labially during treatment were unstable and relapsed to the original lingual position in Class II division 2 malocclusions (p<0.001). There was no significant difference between extraction and non-extraction groups for the amount of lingual relapse of the lower incisors (p>0.05). There was no significant difference between male and female groups for the axial change of the lower incisors (p>0.05). As a result of multiple regression analysis, the cephalometric measurement best predicting the lower incisor position to the A-Pog line post-retention was pre-treatment L1-Apog(mm) and pre-treatment SNGoMe$(^{\circ})$. Because of the instability of labially inclined lower incisors after orthodontic treatment, the treatment goal should be the pre-treatment incisor axial position.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.487-494
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• 2020

The distance between the source and the detector, the diameter of the detector, and the volume effect of the radiation source result in a change in solid angle at the detector entrance, which affects the determination of detection efficiency by causing a difference in path length within the detector. A typical analysis method for calculating solid angles was useful only for a source (⁶⁰Co) with a simple geometric structure, so in this experiment, the distance between the detector and the source was measured by switching on for up to 25 cm with the reference point of window cap 0.5 cm. In addition, 450 and 1000 ㎖ Marinelli beaker of standard volumetric sources were closely adhered to the detector. For circular point sources co-axial with the detector, the change in the solid angle to the distance from the detector window is equal to half the square radius of the source versus the square radius of the detector, if the resulting relationship of the calculation analysis results in the detector being less than the radius of the source. Since the solid angular difference is 0.5 the result of Monte Carlo is acceptable. The relationship between detector and source distance is shown. Solid angles have been verified to decrease rapidly with distance. Measurement and simulation results for a volumetric source show a difference of ±1.01% from a distance of 0 cm and less than 4 % when the distance is reduced to 5 and 10 cm. It can be seen that the longer distance, the smaller efficiency angle, and the exponential increase in attenuation as the energy decreases, is reflected in the calculation of efficiency. Thus, the detection efficiency has proved sufficient for the use of solid angle and Monte Carlo codes.

• Archives of Plastic Surgery
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• v.35 no.1
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• pp.48-55
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• 2008

Purpose: We measured linear distances, angles and inclinations on the cast models of the noses, and compared these indirect measurements with the direct measurements obtained from the nose in order to validate the accuracy of the indirect anthropometry using the cast model. Methods: Subjects were 50 males and 50 females, medical students in twenties(mean 27.1 years). Cast models were made from the alginate impression material and the plaster. In direct anthropometry, 16 linear, 7 angular, and 2 inclination measurements between 11 landmarks on the nose were obtained using sliding caliper, spreading caliper, and fabric tape measure. At the same time, the same measurements were obtained from the cast models of the same people. Total 25 measurements were compared, and tested by the independent t-test of SPSS. Results: The standard values of Korean nose in twenties were obtained. 24 measurements except the columellar labial angle were not statistically different between the indirect anthropometry and the direct anthropometry. Conclusion: Indirect anthropometry on the cast model of the nose revealed no significant difference from the anthropometric measurement statistically, accounting for 24 in 25 measurements(96%). There are two possible reasons that caused the difference of columellar labial angle between direct and indirect anthropometry. First, the columellar labial angle could be decreased by protrusion of the lips which resulted from contracting mouth in which an drinking straw had been applied on the mouth corner for patients' respiration during making cast model. Second, it is generally known that the columellar labial angle could be measured larger when soft tissues were pressed by protractor in direct anthropometry. Using a drinking straw with greater diameter, and scheming respiration through the nostrils that patients don't feel discomfort, the more accurate data would be obtained from the indirect anthropometry using the cast models of the noses.

• The korean journal of orthodontics
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• v.35 no.2 s.109
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• pp.91-105
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• 2005

For af accurate diagnosis and treatment planning of facial asymmetry, the use of 3-dimensional (3-D) image is indispensable. The purpose of this study was to get standard data for the 3-D analysis of facial asymmetry Computerized tomography (CT) was taken in the 60 normal occlusion individuals (30 male. 30 female) who did not have any apparent facial asymmetry. The acquired 2D CT DICOM data were input on a computer, and the reformatted 3-D images were created using a 3-D image software. Twenty three measurements were established in order to evaluate asymmetry; 15 ;omear measurements (6 for ramus length. 1 for condylar neck length, and 8 for mandibular body length) and 8 angular measurements (4 for gonial angle. 2 for frontal ramal inclination. and 2 for lateral ramal inclination) The right aid left difference of each measurement was calculated and analyzed. It is suggested that the right and left differences of the measurements obtained from the study could be used as references for the diagnosis of facial asymmetric patients.

• The korean journal of orthodontics
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• v.36 no.1 s.114
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• pp.14-29
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• 2006

Developments in computer technology have made possible the 3-dimensional (3-D) evaluation of hard and soft tissues in orthodontic diagnosis, treatment planning and post-treatment results. In this study, Korean adults with normal occlusion (male 30, female 30) were scanned by a 3-D laser scanner, then 3-D facial images formed by the Rapidform 2004 program (Inus Technology Inc., Seoul, Korea.). Reference planes in the facial soft tissue 3-D images were established and a 3-D coordinate system (X axis-left/right, Y axis-superior/inferior, Z axis-anterior/posterior) was established by using the soft tissue nasion as the zero point. Twenty-nine measurement points were established on the 3-D image and 43 linear measurements, 8 angular measurements, 29 linear distance ratios were obtained. The results are as follows; there were significant differences between males and females in the nasofrontal angle $(male:\;142^{\circ},\;female:\;147^{\circ})$ and transverse nasal prominence $(male:\;112^{\circ},\;female:\;116^{\circ})$ (p<0.05). The transverse upper lip prominence was $107^{\circ}$ in males, $106^{\circ}$ in females and the transverse mandibular prominence was $76^{\circ}$ in both males and females. Li-Me' was 0.4 times the length of Go-Me'(mandibular body length) and the mouth height was also 0.4 times the width of the mouth width. The linear distance ratio from the coronal reference plane of FT, Zy, Pn, ULPm, Li, Me' was -1/-1/1/0.5/0.5/-0.6 respectively. The 3-D facial model of Korean adults with normal occlusion were be constructed using coordinate values and linear measurement values. These data may be used as a reference in 3-D diagnosis and treatment planning for malocclusion and dentofacial deformity patients and applied for 3-D analysis of facial soft tissue changes before and after orthodontic treatment and orthognathic surgery.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.141-145
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• 2005

Purpose : It is known that the neutron is generally generated from the photon, its energy is larger than 10 MV. The neutron is leaked in the container inspection system installed at the customs though its energy is below 9 MV. It is needed that the spacial effect of the neutrons released from radiation treatment machine, linac, installed in the medical canter. Materials and Methods : The medical linear accelerator(Clinac 1800, varian, USA) was used in the experiment. Measuring neutron was used bubble detector(Bubble detector, BDPND type, BTI, Canada) which was created bubble by neutron. The bubble detector is located on the medical linear accelerator outskirt in three different distance, 30, 50, 120 cm and upper, lower four point from the iso-center. In addition, for effect on protect material we have measured eight points which are 50 cm distance from iso-center. The SAD(source-axis-distance), distance from photon source to iso-center, is adjusted to 100 cm and the field size is adjusted to $15{\times}15cm^2$. Irradiate 20 MU and calculate the dose rate in mrem/MU by measuring the number of bubble. Results : The neutron is more detected at 5 position in 30, 50 cm, 7 position in 120 cm and with wedge, and 2 position without mount. Conclusion : Though detection position is laid in the same distance in neutron measurement, the different value is shown in measuring results. Also, neutron dose is affected by the additional structure, the different value is obtained in each measurement positions. So, it is needed to measure and evaluate the neutron dose in the whole space considering the effect of the distance, angular distribution and additional structure.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.115-121
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• 2013

Purpose: Latest linear accelerator and the introduction of new measurement equipment to the agency that the introduction of this equipment in the future, by analyzing the process of confirming the usefulness of the preparation process for applying it in the clinical causes some problems, should be helpful. Materials and Methods: All measurements TrueBEAM STX (Varian, USA) was used, and a file specific to each energy, irradiation conditions, the dose distribution was calculated using a computerized treatment planning equipment (Eclipse ver 10.0.39, Varian, USA). Measuring performance and cause errors in MapCHECK 2 were analyzed and measured against. In order to verify the performance of the MapCHECK 2, 6X, 6X-FFF, 10X, 10X-FFF, 15X field size $10{\times}10$ cm, gantry $0^{\circ}$, $180^{\circ}$ direction was measured by the energy. IGRT couch of the CT values affect the measurements in order to confirm, CT number values : -800 (Carbon) & -950 (COUCH in the air), -100 & 6X-950 in the state for FFF, 15X of the energy field sizes $10{\times}10$, gantry $180^{\circ}$, $135^{\circ}$, $275^{\circ}$ directionwas measured at, MapPHAN allocated to confirm the value of HU were compared, using the treatment planning computer for, Measurement error problem by the sharp edges MapPHAN Learn gantry direction MapPHAN of dependence was measured in three ways. GANTRY $90^{\circ}$, $270^{\circ}$ in the direction of the vertically erected settings 6X-FFF, 15X respectively, and Setting the state established as a horizontal field sizes $10{\times}10$, $90^{\circ}$, $45^{\circ}$, $315^{\circ}$, $270^{\circ}$ of in the direction of the energy-6X-FFF, 15X, respectively, were measured. Without intensity modulated beam of the third open arc were investigated. Results: Of basic performance MapCHECK confirm the attenuation measured by Couch, measured from the measured HU values that are assigned to the MAP-PHAN, check for calculation accuracy for the angled edge of the MapPHAN all come in a range of valid measurement errors do not affect the could see. three ways for the Gantry direction dependence, the first of the meter built into the value of the Gantry $270^{\circ}$ (relative $0^{\circ}$), $90^{\circ}$ (relative $180^{\circ}$), 6X-FFF, 15X from each -1.51, 0.83% and -0.63, -0.22% was not affected by the AP/PA direction represented. Setting the meter horizontally Gantry $90^{\circ}$, $270^{\circ}$ from the couch, Energy 6X-FFF 4.37, 2.84%, 15X, -9.63, -13.32% the difference. By-side direction measurements MapPHAN in value is not within the valid range can not, because that could be confirmed as gamma pass rate 3% of the value is greater than the value shown. You can check the Open Arc 6X-FFF, 15X energy, field size $10{\times}10$ cm $360^{\circ}$ rotation of the dose distribution in the state to look at nearly 90% pass rate to emerge. Conclusion: Based on the above results, the MapPHAN gantry direction dependence by side in the direction of the beam relative dose distribution suitable for measuring the gamma value, but accurate measurement of the absolute dose can not be considered is. this paper, a more accurate treatment plan in order to confirm, Reduce the tolerance for VMAT, such as lateral rotation investigation in order to measure accurate absolute isodose using a combination of IMF (Isocentric Mounting Fixture) MapCHEK 2, will be able to minimize the impact due to the angular dependence.

• The korean journal of orthodontics
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• v.18 no.2
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• pp.459-474
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• 1988

A study was made of a method of rational assessment on the roentgeno-cephalogram in orthodontic practice. Fifty eight measurements were analyzed on the roentgeno-cephalograms of 50 male and 50 female Korean adults with the acceptable profile and the normal occlusion. The means and standard deviations of measurements were studied in male and female groups by various analytic methods, and the sex difference was examined statistically. The obtained data were compared with those of the Japanese and American standards by useing a Japanese adults standard polygon chart reported by lizuka and Ishikawa. Amongs of 58 measurements, 14 have been selected as statistically significant and clinically useful, and used to make a Korean adult standard polygon chart. The results obtained were as follows: 1. Standards for cphalometric analysis in Korean adults were obtained, and the polygon chart and cephalometric profilogram were also made by using the standards in order to apply to a clinical diagnosis. 2. The sex difference was recognized in linear measurements, but not in angular measurments. 3. In comparison with the American standards from Downs and Graber, the Korean showed significant differences in angle of convexity, mandibular plane angle, Y-axis angle, interincisal angle and lower incisor to mandibular plane angle. Thus, the Korean showed a more retruded chin position, convex facial type, than white people. 4. In comparison with the Japanese standards from Iizuka and Ishikawa, the Korean showed a significant similarity with the Japanese, especially in females. 5. Upper incisor to Huxely line angle, established as a new measurement, proved to be paralell to X-Y axis angle.

• The korean journal of orthodontics
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• v.29 no.2 s.73
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• pp.239-249
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• 1999

In orthognathic surgery to obtain proper functional and esthetic form after skeletal discrepancy treatment, precise diagnosis and treatment plan are essential. Especially in two jaw surgeries that have serious upper and lower jaw problems, maxilla and mandible are arranged in three dimensions. Based on the maxillary rearrangement, mandibular sagittal and transverse positions are determined, and thus new occlusal plane is established. The object of this study is to evaluate the stability of the indiviual ideal occlusal plane based on the architectural and structural craniofacial analysis of Delaires. The subjects of this study were 48 patients who underwent two jaw surgeries, and they were equally divided into two groups, A and B. A group was operated with ideal occlusal plane and B group was not. Two groups were compared at the preoperative, immediate postoperative (average 4.3days), and long-term postoperative (average 1.3years) lateral cephalometric radiographs. The following results were obtained: 1. ANS was lower than that of PNS for both A and B after the surgery. That is, maxilla and mandible are rotated in posterior and superior direction. 2. Significances were found between $T_2$ and $T_3$ for both A and B are HRP-Me at vortical measurements, articular angle(p<0.01), gonial angle(p<0.01), and Mn. plane angle(p<0.05) at angular measurement. Mn. plane angle is increased at HRP-Me is decreased for both A and B. 3. There is no significance in skeletal stability aster the surgery between group A and B. 4. Horizontal movements of B and Pog by surgery have statistically significant inverse correlations with horizontal relapse of B and Pog, and vertical relapse of PNS, as well as Mn. Plane angle, and gonial angle after the surgery.

• The korean journal of orthodontics
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• v.37 no.6
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• pp.421-431
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• 2007

The objective of this study was to provide guidelines for the diagnosis and successful treatment of orthodontic treatment with upper premolar extraction only Methods: The sample group consisted of 40 patients (20 with upper premolar extraction only, 20 with both upper and lower premolar extractions) who showed an overjet of more than 7 mm and were finished successfully. Lateral cephalographs were taken before and after orthodontic treatment. Landmarks showing the position of the upper and lower incisors and the position of the upper and lower lip were determined and angular measurement of these values were obtained for statistical analysis (Mann-Whitney test). Results: At pre-treatment, the position of the lower incisor was less labially inclined and the convexity of the lower lip was smaller in the upper premolar extraction only group than in the upper/lower premolar extraction group. At post-treatment, there was no difference in all measurements except for the position of the lower incisor. A comparison of changes between pre- and post-treatment showed that the retraction of upper & lower incisors and the decrease in convexity of the lower lip were greater in the upper/lower premolar extraction group. Conclusions: Treatment by upper premolar extraction can be of benefit for patients whose lower incisor proclination and lower lip protrusion are not excessive.