• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.12-17
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• 2012

Purpose : The patient's clothes and sheet after radioiodine therapy must be disposed of by related regulation. That must be disposed of as radioactive wastes, but that is reusing after radioactivity decay by keeping for the certain period of time. In general, The minimum storage period calculate by standard of take radioactive substance out of radiation controlled area based on measured surface contamination level. But the measurements of surface contamination level are able to differ by measurement method. In this paper, I wish to calculate the minimum storage period of patient's clothes and sheet after radioiodine therapy by measure nuclide concentration offered by the regulation on self-disposal of radioactive wastes. Materials and Methods : The whole area of patient's clothes and sheet measured 31 patients(male:9 patients, female:22 patients), who had radioiodine therapy(3.7 GBq:13 patients, 5.55 GBq:16 patients, 7.4 GBq:2 patients) from july 2011 to march 2012. The minimum storage period is calculated by the regulation on self-disposal of radioactive waste(100 Bq/g) and standard of take radioactive substance out of radiation controlled area(4 kBq/m2) Results : The minimum storage period of pillow sheet, upper uniform, lower uniform by standard of take radioactive substance out of radiation controlled area were each 4.6 days, 63days, 78 days. The minimum storage period of pillow sheet, upper uniform, lower uniform by the regulation on self-disposal of radioactive waste were each 18.1 days, 43 days, 62 days. Conclusion : We can verify that patient's clothes and sheet after radioiodine therapy exists a great deal of radioactive contamination. The minimum storage period calculation of patient's clothes and sheet is better suited to applying nuclide concentration offered by the regulation on self-disposal of radioactive waste. I recommend, To keep for at least 2 months of the patient's clothes and sheet contaminated radioactivity, for prevent contamination and unnecessary radiation exposure.

• Progress in Medical Physics
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• v.23 no.4
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• pp.269-278
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• 2012

Aquaplast Thermoplastic (AT) is a tissue-equivalent oral compensator that has been developed to improve dose uniformity at the common boundary and around the treated area during radiotherapy in patients with head and neck cancer. In order to assess the usefulness of AT, the degree of improvement in dose distribution and physical properties were compared to those of oral compensators made using paraffin, alginate, and putty, which are materials conventionally used in dental imprinting. To assess the physical properties, strength evaluations (compression and drop evaluations) and natural deformation evaluations (volume change over time) were performed; a Gafchromic EBT2 film and a glass dosimeter inserted into a developed phantom for dose verification were used to measure the common boundary dose and the beam profile to assess the dose delivery. When the natural deformation of the oral compensators was assessed over a two-month period, alginate exhibited a maximum of 80% change in volume from moisture evaporation, while the remaining tissue-equivalent properties, including those of AT, showed a change in volume that was less than 3%. In a free-fall test at a height of 1.5 m (repeated 5 times as a strength evaluation), paraffin was easily damaged by the impact, but AT exhibited no damage from the fall. In compressive strength testing, AT was not destroyed even at 8 times the force needed for paraffin. In dose verification using a glass dosimeter, the results showed that in a single test, the tissue-equivalent (about 80 Hounsfield Units [HU]) AT delivered about 4.9% lower surface dose in terms of delivery of an output coefficient (monitor unit), which was 4% lower than putty and exhibited a value of about 1,000 HU or higher during a dose delivery of the same formulation. In addition, when the incident direction of the beam was used as a reference, the uniformity of the dose, as assessed from the beam profile at the boundary after passing through the oral compensators, was 11.41, 3.98, and 4.30 for air, AT, and putty, respectively. The AT oral compensator had a higher strength and lower probability of material transformation than the oral compensators conventionally used as a tissue-equivalent material, and a uniform dose distribution was successfully formed at the boundary and surrounding area including the mouth. It was also possible to deliver a uniformly formulated dose and reduce the skin dose delivery.

• Journal of Life Science
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• v.26 no.6
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• pp.633-639
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• 2016

Biomaterials including polymer, metal, ceramic, and composite have been widely applied for medical uses as medical fibers, artificial blood vessels, artificial joints, implants, soft tissue, and plastic surgery materials owing to their physicochemical properties. However, the biocompatibility and toxicity for film- and plate-form biomaterials is difficult to measure in mammalian cells because there is no appropriate incubation system. To solve these problems, we developed a novel mammalian cell culture system consisting of a silicone ring, top panel, and bottom panel and we applied two polymer films (PF) and one metal plate (MP). This system was based on the principal of sandwiching a test sample between the top panel and the bottom panel. Following the assembly of the culture system, SK-MEL-2 cells were seeded onto Styela Clava Tunic (SCT)-PF, NaHCO₃-added SCT (SCTN)-PF, and magnesium MP (MMP) and incubated at 37℃ for 24 hr and 48 hr. An MTT assay revealed that cell viability was maintained at a normal level in the SCT-PF culture group at 24 or 48 hr, although it rapidly decreased in the SCTN-PF culture group at 48 hr. Furthermore, the cell viability in the MMP culture group was very similar to that of the control group after incubation for 24 hr and 48 hr. Together, these results suggest the sandwich-type mammalian culture system developed here has the potential for the evaluation of the biocompatibility and toxicity of cells against PF- and MP-form biomaterials.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.67-75
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• 2022

The aim of this study is to establish a new QC method that can simultaneously evaluate the resolution of the x/y plane and the z-axis by producing a phantom that can reflect exposure and reconstruction parameter of MDCT system. It was used with Aquilion ONE(Cannon Medical System, Otawara, Japan), and the examination was scanned using of 120 kV, 260 mA, and the D-FOV of 300 mm². It produced new SSP phantom modules in which two aluminum plates inclined at 45° to a vertical axis and a transverse axis to evaluate high contrast resolution of x/y plane and z axis. And it changed factors such as the algorithm, distance from gantry iso-center. All images were reconstructed in five steps from 0.6 mm to 10.0 mm slice thickness to measure resolution of x/y plane and z-axis. The image data measured FWHM and FWTM using Profile tool of Aquarius iNtusion Edition ver. 4.4.13 P6 software(Terarecon, California, USA), and analysed SPQI and signal intensity by ImageJ program(v1.53n, National Institutes of Health, USA). It decreased by 4.09~11.99%, 4.12~35.52%, and 4.70~37.64% in slice thickness of 2.5 mm, 5.0 mm, and 10.0 mm for evaluating the high contrast resolution of x/y plane according to distance from gantry iso-center. Therefore, the high contrast resolution of the x/y plane decreased when the distance from the iso-center increased or the slice thickness increased. Additionally, the slice thicknesses of 2.5 mm, 5.0 mm, and 10.0 mm with a high algorithm increased 74.83, 15.18 and 81.25%. The FWHM was almost constant on the measured SSP graph for evaluating the accuracy of slice thickness which represents the resolution of x/y plane and z-axis, but it was measured to be higher than the nominal slice thickness set by user. The FWHM and FWTM of z-axis with axial scan mode tended to increase significantly as the distance increased from gantry iso-center than the helical mode. Particularly, the thinner slice thickness that increased error range compare with the nominal slice thickness. The SPQI increased with thick slice thickness, and that was closer to 90% in the helical scan than the axial scan. In conclusion, by producing a phantom suitable for MDCT detectors and capable of quantitative resolution evaluation, it can be used as a specific method in the management of research quality and management of outdated equipment. Thus, it is expected to contribute greatly to the discrimination of lesions in the field of CT imaging.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.4
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• pp.446-454
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• 2017

Recently, there have been many studies on bulk-fill resin composites. However, studies on the proper materials for pediatric patients are rare. The aim of this study was to compare the cavity wall adaptation of bulk-fill resin composites with conventional resin composite in class II cavities of primary molars using microcomputed tomography (micro-CT). Standardized class II slot cavities were prepared in 80 exfoliated primary molars and randomly divided into 4 groups. The control group was restored with conventional resin composite, Filtek Z-350 XT (FZ), and the three groups were restored with bulk-fill resin composites, Filtek bulk-fill posterior (FB), Tetric N-Ceram Bulk Fill (TNC), Filtek bulk-fill flowable (FBF). All specimens were thermocycled and then immersed in 50% silver nitrate ($AgNO_3$) solution. Micro-CT was used to measure the penetration volume of the total silver nitrate and the degree of cervical marginal leakage and the number, size, and position of the voids were evaluated. The results revealed that the volume of silver nitrate were significantly different between FB and FZ (p < 0.05). The results also revealed that the penetration length of silver nitrate FBF showed statistically lower than the FZ and FB (p < 0.05). There was no significant difference between the groups in number and size of voids. In conventional resin composite, most of the voids were present inside the restoration (83.3%), but the voids in the bulk-fill resin composites incidence were higher in the gingivoaxial angle. The cavity wall adaptation demonstrated in class II restorations of primary molar by new bulk fill resin composites was similar to conventional incremental technique. Bulk-fill resin composites might be an clinical option for a faster restoration in deciduous teeth.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.1-7
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• 2018

As part of a research dedicated to the field evaluation of the durability of concrete subjected to freezing-thawing, this study analyzes the relationship between the surface roughness and the relative dynamic elastic modulus through image analysis. Four mix compositions with water-to-binder ratios (W/B) of 40%, 50%, 60% and 70% and without AE agent were considered to provoke early freezing. The basic physical properties of the mixes including the relative dynamic elastic modulus and the compressive strength were first evaluated experimentally according to W/B. Then, tests were performed to measure the surface roughness followed by photographs and SEM image analysis. The measured surface roughness tended to increase with larger number of freezing-thawing cycles regardless of W/B. The relative dynamic elastic modulus appeared to increase gradually with the number of cycles for the relatively denser mixes with W/B of 40% and 50%. Besides, the surface roughness increased only at rupture for the mixes with W/B of 60% and 70%. Moreover, the analysis of the photographs of the surface of the mixes with W/B of 40% and 50% revealed that the degradation progressed gradually from the surface with the freezing-thawing cycles. However, for the mixes with W/B of 60% and 70%, apparent change of the surface remained very insignificant until rupture at which damage like cracking could be observed. Consequently, the analysis of surface photograph or the measurement of the surface roughness presented some limitation in assessing the degree of freezing-thawing-induced degradation in case of relatively porous specimens. On the other hand, the photograph and surface roughness appeared to be sufficient for assessing such degradation for the mixes with W/B of 40% and 50%. Accordingly, the image of the surface and the surface roughness are potentially applicable on site for the assessment of freezing-thawing damages in relatively dense mixes.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.208-221
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• 2007

The fracture toughness test is believed as a clinically relevant method for assessing the fracture resistance of the dentinal restoratives. The objectives of this study were to measure the fracture toughness $(K_{1C})$ and microtensile bond strength of dentin-resin composite interface and compare their relationship for their use in evaluation of the integrity of the dentin-resin bond. A minimum of six short-rod specimens for fracture toughness test and fifteen specimens for microtensile bond strength test was fabricated for each group of materials used. After all specimens storing for 24 hours in distilled water at $37^{\circ}C$, they were tensile-loaded with an EZ tester universal testing machin. Statistical analysis was performed using ANOVA and Tukey's test at the 95% confidence level, Pearson's coefficient was used to verify the correlation between the mean of fracture toughness and microtensile bond strength. FE-SEM was employed on fractured surface to describe the crack propagation. Fracture toughness value of Clearfil SE Bond (SE) was the highest, followed by Adper Single Bond 2 (SB), OptiBond Solo (OB), ONE-STEP PLUS (0S), ScotchBond Multi-purpose (SM) and there was significant difference between SE and other 4 groups (p < 0.05). There were, however, no significant difference among SB, OB, OS, SM (p > 0.05). Microtensile bond strength of SE was the highest, followed by SB, OB, SM, OS and OS only showed significant lower value (p < 0.05). There was no correlation between fracture toughness and microtensile bond strength values. FE-SEM examination revealed that dentin bonding agent showed different film thickness and different failure pattern according to the film thickness. From the limited results of this study, it was noted that there was statistically no correlation between K1C and ${\mu}TBS$. We can conclude that for obtaining the reliability of bond strength test of dentin bonding agent, we must pay more attention to the test procedure and its profound scrutiny.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.5
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• pp.19-32
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• 2012

The purpose of this study is to quantitatively measure the view target and the view area through the selection of landscape control point by selecting Jimyeong-dong Dong-gu and Yeongyeong-dong Buk-gu Daegu, which are planned as the large scale housing complex development area, as the target places. It is very meaningful that from the simulation based on this measurement, the improvement methods are attempted to be suggested at the project level. The results of this study are as follows. First, the total number of viewing targets derived from the literature analysis for the selection of the viewing targets was 24, and finally derived main viewing targets were 4 places. Second, the total number of selection criteria of the derived landscape control point was 15, and these were re-categorized as prospect, accessibility and publicness according to the common property. The preliminary LCPs were selected by measuring the publicness and accessibility, and because of the said measurement, a total of 43 preliminary LCPs were selected. The final LCPs were selected by estimating the prospect of the selected preliminary LCPs, and as a result of estimation, a total of 29 final LCPs were selected. Finally, the total number of evaluation indicators derived from literature analysis was 26. Because of the valuation by the landscape control point, it was found that the 2 view areas were the I grade, 3 areas were II grade and 3 areas were the V grade, the lowest grade among 29 view areas. From the analysis on problems for the improvement methods, 4 improvement-indicators including the diversity of land mosaic were selected for the view area-1 without considering the development project drawing. In addition, for the view area-2 with considering the development project drawing, the landscape as the scenery forests was well formed, and the arrangement of architectures for the security of view corridor was right angle arrangement, and their floor number was 10.

• The korean journal of orthodontics
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• v.29 no.4 s.75
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• pp.483-490
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• 1999

Interdental enamel stripping is an usual method for correction of abnormal tooth shape and tooth size discrepancy which is one of the etiologic factors of malocclusion. Clinically it Is useful to correct the minor crowding in anterior teeth and posterior occlusion during finishing stage of orthodontic treatment. But this procedure has risks such as irreversible tooth reduction and remaining roughness of enamel surface can accumulate plaque which can evoke periodontal problem. Even if various methods were introduced to minimize the enamel surface roughness, their evaluation was limited in morphologic differences by scanning electronic microscope(SEM). The purpose of this study was to compare the various interdental enamel stripping method by SEM and to quantify the difference of surface roughness by use of Surfcorder SEF-30D(Kosaka Lab. Ltd.) which can measure the roughness of surface. The stripping methods were divided into mechanical and mechanical-chemical method. Air-rotor stripping and separating strip were used for mechanical stripping and $37\%$ phosphoric acid was used for chemical stripping. The enamel surface roughness after mechanical or mechanical-chemical stripping of interproximal surfaces of premolars which were extracted for orthodontic purpose were measured and compared by means of SEM and $Surfcorder^{\circledR}$, the results were as follows. 1. Enamel surface of primary treated by coarse diamond bur and separating strip groups showed highest value of roughness. 2. To compare the primary treated groups between mechanical and mechanical-chemical method, the latter group showed lower value of roughness remarkably. 3. Mechanical stripping groups which were treated both coarse and fine instrument showed lower value of roughness as much as non treated group. 4. The use of Pumice for final polishing did not show significantly smoothening the stripped enamel surface any more.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.107-114
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• 2014

Purpose : The purpose of this study is evaluation for the applicability of O-MAR(Metal artifact Reduction for Orthopedic Implants)(ver. 3.6.0, Philips, Netherlands) in head & neck radiation treatment planning CT with metal artifact created by dental implant. Materials and Methods : All of the in this study's CT images were scanned by Brilliance Big Bore CT(Philips, Netherlands) at 120kVp, 2mm sliced and Metal artifact reduced by O-MAR. To compare the original and reconstructed CT images worked on RTPS(Eclipse ver 10.0.42, Varian, USA). In order to test the basic performance of the O-MAR, The phantom was made to create metal artifact by dental implant and other phantoms used for without artifact images. To measure a difference of HU in with artifact images and without artifact images, homogeneous phantom and inhomogeneous phantoms were used with cerrobend rods. Each of images were compared a difference of HU in ROIs. And also, 1 case of patient's original CT image applied O-MAR and density corrected CT were evaluated for dose distributions with SNC Patient(Sun Nuclear Co., USA). Results : In cases of head&neck phantom, the difference of dose distibution is appeared 99.8% gamma passing rate(criteria 2 mm / 2%) between original and CT images applied O-MAR. And 98.5% appeared in patient case, among original CT, O-MAR and density corrected CT. The difference of total dose distribution is less than 2% that appeared both phantom and patient case study. Though the dose deviations are little, there are still matters to discuss that the dose deviations are concentrated so locally. In this study, The quality of all images applied O-MAR was improved. Unexpectedly, Increase of max. HU was founded in air cavity of the O-MAR images compare to cavity of the original images and wrong corrections were appeared, too. Conclusion : The result of study assuming restrained case of O-MAR adapted to near skin and low density area, it appeared image distortion and artifact correction simultaneously. In O-MAR CT, air cavity area even turned tissue HU by wrong correction was founded, too. Consequentially, It seems O-MAR algorithm is not perfect to distinguish air cavity and photon starvation artifact. Nevertheless, the differences of HU and dose distribution are not a huge that is not suitable for clinical use. And there are more advantages in clinic for improved quality of CT images and DRRs, precision of contouring OARs or tumors and correcting artifact area. So original and O-MAR CT must be used together in clinic for more accurate treatment plan.