• Radiation Oncology Journal
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• v.18 no.4
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• pp.337-344
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• 2000

Purpose :To design and test test CT simulator phantom for geometrical test. Materials and Methods : The PMMA phantom was designed as a cylinder which is 20 cm in diameter and 24 cm in length, along with a 25$\times25\times31cm^{3}$ rectangular parallelepiped. Radio-opaque wires of which diameter is 0.8 mm are attached on the other surface of the phantom as a spiral. The rectangular phantom was made of four 24$\times24\times0.5 cm^{3}$ square plates and each plate had a 24$\times24 cm^{2}$, 12$\times12cm^{2}$, 6$\times6 cm$^{2}$ square line. The squares were placed to face the cylinder at angles 0 $^{\circ}$ , 15 $^{\circ}$ , 30 $^{\circ}$ ,respectively. The rectangular phantom made it possible to measure the field size, couch angle, the collimator angle, the isocenter shift and the SSD, the measurements of the gantry angle from the cylindrical part. A virtual simulation software, AcOSim, offered various conditions to perform virtual simulations and these results were used to perform the geometrical Quality assurance of CT simulator. Results : A 0.3$\~$0.5 mm difference was found on the 24 cm field size which was created with the DRR measurements obtained by scanning of the rectangular phantom. The isocenter shift, the collimator rotation, the couch rotation, and the gantry rotation test showed 0.5$\~$1 mm, 0.5$\~$l$^{\circ}$ 0.5$\~$ 1$^{\circ}$ , and 0.5-1 $^{\circ}$ differences, respectively. We could not find any significant differences between the results from the two scanning methods. Conclusion :The geometrical test phantom developed in the study showed less than 1 mm (or 1 $^{\circ}$ ) differences. The phantom could be used as a routine geometrical QC/QA tools, since the differences are within clinically acceptable ranges.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.1
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• pp.19-27
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• 2020

Objectives: Pentoxifylline (PTX) is a methylxanthine derivative that has been implicated in the pathogenesis of peripheral vessel disease and intermittent lameness. The purpose of this study was to investigate the effect of PTX and tocopherol in patients diagnosed with osteoradionecrosis (ORN), bisphosphonate-related osteonecrosis of the jaw (BRONJ), and chronic osteomyelitis using digital panoramic radiographs. Materials and Methods: This study was performed in 25 patients who were prescribed PTX and tocopherol for treatment of ORN, BRONJ, and chronic osteomyelitis between January 2014 and May 2018 in Seoul National University Dental Hospital. Radiographic densities of the dental panorama were compared prior to starting PTX and tocopherol, at 3 months, and at 6 months after prescription. Radiographic densities were measured using Adobe Photoshop CS6 (Adobe System Inc., USA). Blood sample tests showing the degree of inflammation at the initial visit were considered the baseline and compared with results after 3 to 6 months. Statistical analysis was performed using the Mann-Whitney test and repeated measurement ANOVA using IBM SPSS 23.0 (IBM Corp., USA). Results: Eight patients were diagnosed with ORN, nine patients with BRONJ, and the other 8 patients with chronic osteomyelitis. Ten of the 25 patients were men, average age was 66.32±14.39 years, and average duration of medication was 151.8±80.65 days (range, 56-315 days). Statistically significant increases were observed in the changes between 3 and 6 months after prescription (P<0.05). There was no significant difference between ORN, BRONJ, and chronic osteomyelitis. Only erythrocyte sedimentation rate (ESR) was statistically significantly lower than before treatment (P<0.05) among the white blood cell (WBC), ESR, and absolute neutrophil count (ANC). Conclusion: Long-term use of PTX and tocopherol can be an auxiliary method in the treatment of ORN, BRONJ, or chronic osteomyelitis in jaw.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.109-126
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• 1993

Refractory periodontitis manifest progressive attachment loss in a rapid and unrelenting manner regardless of the type or frequency of therapy applied. The purpose of this study was ta evaluate the relation between the level of cytokines in GCF and periodontopathic microflora with disease activity of refractory periodontitis. Selection of patients with refractory periodontitis (7 males, 3 females) were made by long term clinical observation including conventional clinical history and parameters. Teeth that showed pocket depth greater than 6mm were selected as sample teeth. Subjects were examined at baseline and after 3 months. Prior to baseline test, individual acrylic stent was fabricated. Reference grooves were made on each sample tooth site. Pocket depth and attachment loss were measured by Florida Probe. Gingival index was measured at 4 sites each sample teeth. Disease activity was defined as attachment loss of ${\ge}$ 2.1mm, as determined by sequential probing and tolerance method. The pattern and amount of alveolar bone resorption was observed with quantitative digital subtraction image processing radiography. Morphological analysis of subgingival bacteria was taken by phase contrast microscopy. Predominant cultivable bacterial distribution and frequency were compared between disease-active and disease-inactive site using immunofluorescence microscopy and selective microbial culturing. Levels of $interleukin-l{\beta}$, 2, 4, 6 and $TNF-{\alpha}$ in GCF and blood serum sample were quantified by ELISA. In active sites, P. intermedia was significantly increased to compare with inactive site. $IL-1{\beta}$, IL-2, IL-6 and $TNF-{\alpha}$ in GCF were increased in active sites and IL-2 in serum was increased in active patients significantly. Alveolar bone loss in active site was correlated with $IL-1{\beta}$, IL-2 in GCF. And loss of attachment in active site was correlated with IL-2 in GCF. These results demonstrate that IL-2 in serum, $IL-1{\beta}$, IL-2, IL-6 and $TNF-{\alpha}$ in GCF, P, intermedia might be used as possible predictors of disease activity in refractory periodontitis before it is clinically expressed as attachment loss and quantitative alveolar bone change.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.2
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• pp.103-109
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• 2016

Purpose: This study is to evaluate the clinical significance of implantation with simultaneous bone graft by comparing the marginal bone loss around maxillary anterior implants with or without bone graft. Materials and methods: Patients treated with implant-retained restorations on maxillary anterior region at Implant Center, Dental Hospital, Wonkwang University between June 2011 and May 2014 were included in this study. Date of implant placement, implant diameter, implant length, implant-abutment connection type and whether the bone graft was done were investigated. The patient's periapical radiographs taken immediately after implantation and at the most recent visit were compared. Marginal bone loss was measured using Emago advanced v5.6 program (Oral diagnostic systems, Amsterdam, Netherlands). Statistical analysis was done in independent t-test by using SPSS 22.0 program. Results: As a result of observing on 83 implants (without bone graft: 44, with bone graft: 39) of 52 patients for 6 - 45 months (average: 18.4 months), implants without bone graft showed $1.42{\pm}0.42mm$, implants with bone graft showed $1.28{\pm}0.45mm$ of marginal bone loss. Conclusion: In limitations of this study, implants with simultaneous bone graft had significantly less marginal bone loss than implants without bone graft.

• Journal of Radiation Protection and Research
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• v.29 no.4
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• pp.231-236
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• 2004

An imaging plate(IP) detector, a two-dimensional digital radiation detector that can acquire image of radioactivity distribution in a sample, has been applied in many fields; for industrial radiography, medical diagnosis, X-ray diffraction test, etc. In this study, the possibility of IP detector to be used lot measuring radioactivity of sample is explored using its high sensitivity, higher spatial resolution, wider dynamic range and screen uniformity for several kinds radiations. First, the IP detector is applied to measure the surface uniformity for area source. Surface uniformity is measured rapidly and nondestructively by measuring the radioactivity distribution of common standard area source$(^{241}Am)$. Next, the IP is employed to study the possibility of measuring an extremely low-level activity of environmental sample. For this study the screen uniformity, shield effect of background radiation, linear dynamic range and fading effect of the IP detector is investigated. The potato, banana, radish and carrot samples are chosen to measure ultra low-level activity of $^{40}K$ isotope. The efficiency calibration of IP detector is carried out using the standard source.

• Journal of the Korean Society of Radiology
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• v.18 no.4
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• pp.345-353
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• 2024

The purpose of this study was to suggest an appropriate collimation size and central X-ray incidence point by analyzing the correlation between the collimation size used in lumbar lateral examination and factors affecting the collimation size. the lumbar lateral examination results of 148 patients suitable for the purpose of this study were analyzed. The measurement method was to set the total horizontal width shown in the image to the size of the irradiation field(collimation) used during the examination. The distance connected vertically from the end of the dorsal field to the apophyseal joint of the third lumbar vertebra(AJD), the distance from the dorsal end of the image field to the center of the body of the third lumbar vertebra(BD), and the distance from the end of the dorsal field of the image to the center of the pedicle of the third lumbar vertebra(PD). The distance was measured. For comparative analysis of the mean values of dependent variables according to gender, age, height, weight, and body mass index, the mean values were compared using the independent samples t test and one-way ANOVA. For post hoc analysis, duncan was used. The correlation between independent and dependent variables was analyzed using Pearson correlation analysis. In this study, statistical significance was set at a p value of 0.05 or lower. The average value of the collimation size during the lumbar spine lateral examination was 252.45 mm, AJD was 102.11 mm, BD was 141.17 mm, and PD was 119.73 mm. The mean values of collimation size, AJD, BD, and PD were larger in men than in women, but statistical significance for the difference in mean values by gender was found only in BD (p<0.05). There was a slight difference in the mean value of each group according to age, but there was no statistical significance (p>0.05). The collimation size and mean values of AJD, BD, and PD according to height, weight, and body mass index differed depending on the independent variables, and the differences were all statistically significant (p<0.05). As a result of the correlation analysis, field size and AJD, BD, and PD showed no correlation with gender and age, a weak positive correlation with height, and a medium positive correlation with weight and body mass index. The results of this study showed that CS was correlated with height, weight, and BMI during lumbar lateral examination. If the entrance point of the central X-ray is moved to the appophyseal joint by considering weight and BMI when adjusting the collimation size in clinical practice, it is expected that the collimation size can be reduced bu about 5%.