• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.165-172
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• 2004

Rice plants were exposed to $I_2$ vapor for 80 min at different growth stages in an exposure box to investigate the parameters concerning direct plant contamination. Deposition velocity $(m\;s^{-1})$ of the $I_2$ vapor for the straws was in the range of $1.4{\times}10^{-5}-1.3{\times}10^{-4}$ depending on the exposure time, being comparatively low during the earlier part of the plant growth. Ear deposition velocity was in the range of $2.5{\times}10^{-5}-6.7{\times}10^{-5}$. Whole-plant deposition velocity was in the range of $1.4{\times}10^{-5}-1.8{\times}10^{-4}$ with the highest from the exposure performed on Aug. 18 (7 d after the start of heading). The time-dependent variation generally decreased when the deposition velocity was normalized to the biomass density No noteworthy tendency in the deposition velocity was observed with regard to the temperature, sunlight and humidity. Translocation factor for the hulled seeds was $3.3{\times}10^{-5}-4.7{\times}10^{-4}$ with the highest from the Aug. 23 exposure. It was found that a leaf deposition even before the ear emergence resulted in a considerable seed translocation.

• Journal of Radiation Protection and Research
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• v.18 no.2
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• pp.71-79
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• 1993

Form the pure Maxwellian distribution(kT= 1.42MeV), the effects upon calibration factors of encapsulating a $^{252}Cf$ spontaneous fission neutron source were investigated to establish a standard neutron field in the Secondary Standard Dosimetry Laboratory at Korea Atomic Energy Research Institute(KAERI). A Monte Carlo code MCNP was used in simulating the encapsulation SR-Cf-100 and SR-Cf-1273 to be real conditions. The anisotropy(FI) and fluence-to-dose equivalents conversion factors$(H/{\Phi})$ were evaluated and compared with other results. As the results, the FI was determined to be 1.061 at ${\theta}=90^{\circ}$ with ${\pm}0.2%$ statistical error and the $(H/{\Phi})$ was evaluated to be $333.9 [pSv\;cm^2]\;with\;{\pm}0.5%$ statistical error, which is lower by 1.8% than that recommended by the ISO 8529. This means physically that the neutron spectrum of the unmoderated $^{252}Cf$ source in KAERI is a little more softened than that by the ISO.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.50-63
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• 2021

Microcephalic osteodysplastic primordial dwarfism type II (MOPD II) is an autosomal recessive inherited disorder form of primordial dwarfism, caused by mutations in the pericentrin gene. The purpose of the study was to examine the clinical and radiological features, physicochemical properties and microstructures of the tooth affected with MOPD II. The mandibular 2nd molar was collected from the MOPD II patient. Micro-computerized tomography, scanning electron microscopy, energy dispersive spectrometry and Vickers microhardness analysis were performed on the MOPD II and the normal control. The morphology of the MOPD II tooth appeared to have malformed pulp and root and showed a small size. The mineral density measurement showed that the MOPD II tooth had similar scores in the enamel, but lower scores in the root 1/2 and apical dentin compared to the normal control. The microhardness values were smaller in the cusp enamel, root 1/2 dentin and apical dentin of the MOPD II compared to the normal control. In this study, the dental characteristics and the physicochemical properties of a tooth affected with MOPD II were analyzed to improve understanding of the oral manifestations of the disease and to assist in proper dental treatment by identifying precautions.

• Korean Journal of Clinical Laboratory Science
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• v.56 no.1
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• pp.52-58
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• 2024

Photodynamic therapy (PDT) activates intracellular oxygen using a photosensitizer activated by light of a specific wavelength and is a potential means of treating wound infections caused by antibiotic-resistant bacteria. Pseudomonas aeruginosa (P. aeruginosa) is typically non-pathogenic in healthy individuals but can induce severe illnesses like sepsis in the immunocompromised. Antibiotics have been conventionally used to treat P. aeruginosa infections, but increasing antibiotic resistance caused by drug misuse poses a growing challenge to the management of these infections. This study aimed to investigate the ability of PDT using photosensitizers (PhotoMed, Methyl pheophorbide A, or Radachlorin^®) and a diode laser to inhibit P. aeruginosa. Suspensions of P. aeruginosa and a photosensitizer were inoculated into Petri dishes and incubated for 30 minutes. Samples were then irradiated with the laser at 3 J/cm², and after incubation, colony areas were measured. P. aeruginosa killing rates were 79.65% for PhotoMed, 47.36% for Methyl pheophorbide A, and 40.91% for Radachlorin^®. This study shows that PDT using a diode laser and a photosensitizer constitutes an effective practical therapeutic approach for inhibiting P. aeruginosa.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.499-508
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• 2000

The purposes of this study were to evaluate the validity of 2 kinds of digital radiography techniques in evaluating the radiopacity comparison of restorative materials and to determine the relative radiopacities of several kinds of compomer and flow able resin using these techniques. After taking radiographs of an aluminum step wedge, con-elation of optical density calibration curves were evaluated between conventional radiography with transmission densitometer and CD-Dent digital radiography (storage phosphor system) and between conventional one and RVG$^{(R)}$ digital radiography (CCD system). Compomers such as Dyract$^{(R)}$ AP, Compoglass$^{(R)}$, and Dyract flow$^{(R)}$, and flowable resins such as Ultraseal-XT$^{(R)}$ plus$^{TM}$, Revolution$^{TM}$, Aeliteflo$^{TM}$ and Tetric-flow$^{(R)}$ were used. Five specimens of 5mm in diameter and 2 mm thick were fabricated with each material. Radiopacities of the materials were measured using the above radiographic techniques and compared. The results were as follows: 1. When the optical density calibration curves were compared, conventional radiography and both CD-Dent and RVG$^{(R)}$ digital radiographies showed very high inverse correlations (${\gamma}$=-0.95, ${\gamma}$=-0.98 ; p<0.05). 2. All the tested restorative materials showed levels of radiopacity the same as or greater than that of dentin (p<0.05), Radiopacities of Dyract$^{(R)}$ AP, Compoglass$^{(R)}$, and Tetric flow$^{(R)}$ were greater than those of Revolution$^{TM}$, Aeliteflo$^{TM}$, or dentin (p<0.05). 3. Radiopacities of Dyract$^{(R)}$ AP, Compoglass$^{(R)}$, and Tetric flow$^{(R)}$ were shown to be greater than that of enamel when conventional radiography and CD-Dent digital radiography were used (p<0.05). Radiopacity of Dyract flow$^{(R)}$ was shown to be greater than that of Enamel when conventional radiography was used (p<0.05).

• Journal of the Korean Orthopaedic Association
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• v.55 no.1
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• pp.54-61
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• 2020

Purpose: Brown tumor is a tumor-like disease that can occur as a linked disease of hyperparathyroidism which can causes osteoporosis, osteitis fibrosa cystica, pathologic fractures. Brown tumor has been reported as a case report, but there is no comprehensive report on the exact diagnosis and principle of management for osseous lesion. The purpose of this study is to report the treatment and results of osseous lesions through 5 cases. Materials and Methods: From February 2004 to May 2015, five cases of Brown tumor were diagnosed in Chosun University Hospital and Chonnam National University Hospital orthopedic department. Medical records and radiographs were reviewed retrospectively. Parathyroid tumors were surgically removed, and surgical treatment and observation were performed for orthopedic osseous lesions. Results: The mean length of the long axis of the symptomatic osseous lesion was 6.2 cm (4.5-9.0 cm). An average of 7.6 (range, 3 to 14) of high uptake osseous lesion showed in whole body bone scan. The absolute value, T-score and Z-score of the vertebrae and proximal femur were adequate for diagnosis of osteoporosis using dual energy X-ray absorptiometry bone mineral density at diagnosis and recovered to normal at the last follow-up. In laboratory tests, serum concentrations of total calcium, ionized calcium, inorganic phosphorus, serum alkaline phosphatase, and parathyroid hormone were helpful to diagnosis and normalized upon successful removal of parathyroid adenoma or cancer. Conclusion: For accurate diagnosis of Brown tumor, it should be accompanied by systemic examination as well as clinical symptoms, laboratory tests and radiologic examination for osseous lesions. And a good prognosis can be expected if the hyperparathyroidism is treated together with the comprehensive treatment of osseous lesions.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.171-176
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• 2014

Purpose : Changing the calculation grid of AAA in Lung SABR plan and to analyze the changes in target dose, and investigated the effects associated with it, and considered a suitable method of application. Materials and Methods : 4D CT image that was used to plan all been taken with Brilliance Big Bore CT (Philips, Netherlands) and in Lung SABR plan($Eclipse^{TM}$ ver10.0.42, Varian, the USA), use anisotropic analytic algorithm(AAA, ver.10, Varian Medical Systems, Palo Alto, CA, USA) and, was calculated by the calculation grid 1.0, 3.0, 5.0 mm in each Lung SABR plan. Results : Lung SABR plan of 10 cases are using each of 1.0 mm, 3.0 mm, 5.0 mm calculation grid, and in case of use a 1.0 mm calculation grid $V_{98}$. of the prescribed dose is about $99.5%{\pm}1.5%$, $D_{min}$ of the prescribed dose is about $92.5{\pm}1.5%$ and Homogeneity Index(HI) is $1.0489{\pm}0.0025$. In the case of use a 3.0 mm calculation grid $V_{98}$ dose of the prescribed dose is about $90{\pm}4.5%$, $D_{min}$ of the prescribed dose is about $87.5{\pm}3%$ and HI is about $1.07{\pm}1$. In the case of use a 5.0 mm calculation grid $V_{98}$ dose of the prescribed dose is about $63{\pm}15%$, $D_{min}$ of the prescribed dose is about $83{\pm}4%$ and HI is about $1.13{\pm}0.2$, respectively. Conclusion : The calculation grid of 1.0 mm is better improves the accuracy of dose calculation than using 3.0 mm and 5.0 mm, although calculation times increase in the case of smaller PTV relatively. As lung, spread relatively large and low density and small PTV, it is considered and good to use a calculation grid of 1.0 mm.

• Progress in Medical Physics
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• v.13 no.4
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• pp.209-217
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• 2002

There have been many studies on the application of the reciprocal advantages of multimodality image to define accurate target volume in the Process of radiation treatment planning. For the proper use of the multimodality images, the registration works between different modality images should be performed in advance. In this study, we selected chamfer matching method and mutual information method as most popular methods in recent image registration studies considering the registration accuracy and clinical practicality. And the two registration methods were analyzed to deduce the optimal registration method according to the characteristics of images. Lung phantom of which multimodality images could be acquired was fabricated and CT, MRI and SPECT images of the phantom were used in this study. We developed the registration program which can perform the two registration methods properly and analyzed the registration results which were produced by the developed program in many different images' conditions. Although the overall accuracy of the registration in both chamfer matching method and mutual information method was acceptable, the registration errors in SPECT images which had lower resolution and in degraded images of which data were removed in some part were increased when chamfer matching method was applied. Especially in the case of degraded reference image, chamfer matching methods produce relatively large errors compared with mutual information method. Mutual information method can be estimated as more robust registration method than chamfer matching method in this study because it did not need the prerequisite works, the extraction of accurate contour points, and it produced more accurate registration results consistently regardless of the images' characteristics. The analysis of the registration methods in this study can be expected to provide useful information to the utilization of multimodality images in delineating target volume for radiation treatment planning and in many other clinical applications.

• 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.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.252-260
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• 2015

This paper describes the technical background for the Korean wildlife radiation dose assessment code, K-BIOTA, and the summary of its application. The K-BIOTA applies the graded approaches of 3 levels including the screening assessment (Level 1 & 2), and the detailed assessment based on the site specific data (Level 3). The screening level assessment is a preliminary step to determine whether the detailed assessment is needed, and calculates the dose rate for the grouped organisms, rather than an individual biota. In the Level 1 assessment, the risk quotient (RQ) is calculated by comparing the actual media concentration with the environmental media concentration limit (EMCL) derived from a bench-mark screening reference dose rate. If RQ for the Level 1 assessment is less than 1, it can be determined that the ecosystem would maintain its integrity, and the assessment is terminated. If the RQ is greater than 1, the Level 2 assessment, which calculates RQ using the average value of the concentration ratio (CR) and equilibrium distribution coefficient (Kd) for the grouped organisms, is carried out for the more realistic assessment. Thus, the Level 2 assessment is less conservative than the Level 1 assessment. If RQ for the Level 2 assessment is less than 1, it can be determined that the ecosystem would maintain its integrity, and the assessment is terminated. If the RQ is greater than 1, the Level 3 assessment is performed for the detailed assessment. In the Level 3 assessment, the radiation dose for the representative organism of a site is calculated by using the site specific data of occupancy factor, CR and Kd. In addition, the K-BIOTA allows the uncertainty analysis of the dose rate on CR, Kd and environmental medium concentration among input parameters optionally in the Level 3 assessment. The four probability density functions of normal, lognormal, uniform and exponential distribution can be applied.The applicability of the code was tested through the participation of IAEA EMRAS II (Environmental Modeling for Radiation Safety) for the comparison study of environmental models comparison, and as the result, it was proved that the K-BIOTA would be very useful to assess the radiation risk of the wildlife living in the various contaminated environment.