• The Korean Journal of Nuclear Medicine
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• v.27 no.2
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• pp.170-174
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• 1993

The quantitative methods for the assessment of the cerebral blood flow using $^{99m}Tc$-HMPAO brain SPECT utilize the measured count distribution in some specific reconstructed tomographic slice or in algebraic summation of a few neighboring slices, rather than the true volumetric distribution, to estimate the relative regional cerebral blood flow, and consequently produce the biased estimates of the true regional cerebral blood flow. This kind of biases are thought to originate mainly from the arbitrarily irregular shape of the cerebral region of interest(ROI) which are analyzed. In this study, a semi-automated method for the direct quantification of the volumetric regional cerebral blood flow estimate is proposed, and the results are compared to those calculated by the previous planar approaches. Bias factors due to the partial volume effect and the uncertainty in ROI determination are not considered presently for the methodological comparison of planar/volumetric assessment protocol.

• Tuberculosis and Respiratory Diseases
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• v.70 no.6
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• pp.504-510
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• 2011

Background: $^{67}Ga$ scintigraphy has been used for years in sarcoidosis for diagnosis and to determine the extent of the disease. The present report is a study of various findings of $^{67}Ga$ scintigraphy in patients with sarcoidosis. Methods: Between 1998 and 2007, 16 patients (male：female, 6:10; age, $35.9{\pm}15.3$ years) with histologically proven sarcoidosis underwent clinical evaluation and $^{67}Ga$ scintigraphy. According to the site of involvement, they were divided into subtypes and analyzed. Results: Sixteen patients with sarcoidosis had involvement of various organs, including lymph nodes (13/16, 81.3%), lung (3/16, 18.8%), muscle (1/16, 6.3%), subcutaneous tissue (1/16, 6.3%), glands (1/16, 6.3%), and bone (1/16, 6.3%). Sites of involved lymph nodes were thorax (12/13, 92.3%), supraclavicular area (5/13, 38.5%), inguinal area (2/13, 15.4%), abdomen (2/13, 15.4%), and pelvis (1/13, 7.7%). Conclusion: Because sarcoidosis frequently involves multiple organs, $^{67}Ga$ scintigraphy is a useful method in for evaluating the whole body. Nuclear medicine physicians should be familiar with the various findings of gallium uptake in sarcoidosis.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.445-455
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• 2005

Purpose: We developed an animal SPECT system using clinical Philips ARGUS scintillation camera and pinhole collimator with specially manufactured small apertures. In this study, we evaluated the physical characteristics of this system and biological feasibility for animal experiments. Materials and Methods: Rotating station for small animals using a step motor and operating software were developed. Pinhole inserts with small apertures (diameter of 0.5, 1.0, and 2.0 mm) were manufactured and physical parameters including planar spatial resolution and sensitivity and reconstructed resolution were measured for some apertures. In order to measure the size of the usable field of view according to the distance from the focal point, manufactured multiple line sources separated with the same distance were scanned and numbers of lines within the field of view were counted. Using a Tc-99m line source with 0.5 mm diameter and 12 mm length placed in the exact center of field of view, planar spatial resolution according to the distance was measured. Calibration factor to obtain FWHM values in 'mm' unit was calculated from the planar image of two separated line sources. Te-99m point source with i mm diameter was used for the measurement of system sensitivity. In addition, SPECT data of micro phantom with cold and hot line inserts and rat brain after intravenous injection of [I-123]FP-CIT were acquired and reconstructed using filtered back protection reconstruction algorithm for pinhole collimator. Results: Size of usable field of view was proportional to the distance from the focal point and their relationship could be fitted into a linear equation (y=1.4x+0.5, x: distance). System sensitivity and planar spatial resolution at 3 cm measured using 1.0 mm aperture was 71 cps/MBq and 1.24 mm, respectively. In the SPECT image of rat brain with [I-123]FP-CIT acquired using 1.0 mm aperture, the distribution of dopamine transporter in the striatum was well identified in each hemisphere. Conclusion: We verified that this new animal SPECT system with the Phlilps ARGUS scanner and small apertures had sufficient performance for small animal imaging.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.31-42
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• 2009

Purpose: As the number of domestic medical institutions installing PET/CT is increasing rapidly, the transfer of PET/CT images among medical institutions is also increasing. Thus, it is necessary to collect the comparative SUV data from several medical institutions' PET/CT systems through a phantom study which semi-quantitatively compares the SUV on one bed, the change scale of the SUV on the slices, and the time of measuring. The phantom study to find differences among the SUVs from various PET/CT offers the opportunity to obtain the reliability of the SUV in PET/CT images. Materials and Methods: Ten PET/CT systems from medical institutions in Korea were used. To obtain the accurate data, the study has been using the radiation detector of Korea Research Institute of Standards and Science to verify. The internal structures of NEMA $phantom^{TM}$ were removed and Six thousand milliliters of distilled water which has 1mCi of $^{18}F$-FDG put into the phantom. The water was properly integrated with $^{18}F$-FDG using magnetic stirrer. The images were acquired at 60, 70, 80, 90, 100, 110 and 120-minutes for 3 minute each. Two hundred square centimeters of region of interests were placed and analyzed. To confirm the usefulness, the correction-table came out from patients' data. Results: The coefficient of variability of the SUV from -11.0 to 9.90 % fell into the range of international standards(${\pm}10%$) along with the SUV on a bed, the change scale of the SUV on the slices, and the time of measuring, except one PET/CT system. Using the data of the differences among the SUVs, we came to withdraw the correction-table ranging from 0.803 to 1.246. The correction-table was confirmed its usefulness through Linear Regression Analysis which was applied to normal cases. Conclusions: Although studies have been made on the variation of the SUV, there is little attention on the standardization of the SUV. Based on this study of the quantitatively comparable data about the SUV accommodating the correction-table, it would help to have more corrective diagnosis.

• The Korean Journal of Nuclear Medicine
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• v.38 no.1
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• pp.74-84
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• 2004

Purpose: Since I-125 emits low energy (27-35 keV) radiation, thinner crystal and collimator could be employed and, hence, it is favorable to obtain high quality images. The purpose of this study was to derive the optimized parameters of I-125 SPECT using a new simulation tool, GATE (Geant4 Application for Tomographic Emission). Materials and Methods: To validate the simulation method, gamma camera developed by Weisenberger et al. was modeled. Nal(T1) plate crystal was used and its thickness was determined by calculating detection efficiency. Spatial resolution and sensitivity curves were estimated by changing variable parameters for parallel-hole and pinhole collimator. Peformances of I-125 SPECT equipped with the optimal collimator were also estimated. Results: in the validation study, simulations were found to agree well with experimental measurements in spatial resolution (4%) and sensitivity (3%). In order to acquire 98% gamma ray detection efficiency, Nal(T1) thickness was determined to be 1 mm. Hole diameter (mm), length (mm) and shape were chosen to be 0.2:5:square and 0.5:10:hexagonal for high resolution (HR) and general purpose (GP) parallel-hole collimator, respectively. Hole diameter, channel height and acceptance angle of pinhole (PH) collimator were determined to be 0.25 mm, 0.1 mm and 90 degree. The spatial resolutions of reconstructed image of the I-125 SPECT employing HR:GP:PH were 1.2:1.7:0.8 mm. The sensitivities of HR:GP:PH were 39.7:71.9:5.5 cps/MBq. Conclusion: The optimal crystal and collimator parameters for I-125 Imaging were derived by simulation using GATE. The results indicate that excellent resolution and sensitivity imaging is feasible using I-125 SPECT.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.1
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• pp.67-71
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• 2015

Purpose At recently, we enter into the aging society and a age-related disease is increasing. Among that, prevalence of degenerative brain disease like Parkin's disease will be increased. So, many radiopharmaceuticals is developed to diagnosis early and to evaluate the performance of therapeutic drugs. Especially $^{18}F-DOPA$ which involved at dopamine synthesis and function of storage is widely used to the diagnosis of Parkinson's disease as well as brain tumors. in the study, we will evaluate the distribution pattern of $^{18}F-DOPA$ at the striatum by using dynamic study. Materials and Methods We used Biograph Truepoint(Siemens, Germany) as PET/CT scanner, injected a $^{18}F-DOPA$ ($600{\pm}30MBq$) to patient (4men, 6women. $67{\pm}11age$) who visited our hospital from June to September, started 95min dynamic study at same time. after finishing acquisition, we reconstructed PET data with 19 frame every 5 minutes, analysed a average counts at ROI's where set at both striatums, anterior putamen, posterior putamen Results Counts in the cerebellum as the background formed a plateau after 90 minutes from the highest out rapidly reduced to 15 minutes. Counts of anterior putamen and posterior gradually increased but formed a plateau after 60min. A count ratio of Striatum to cerebellum was continuously increased up to more than 95 minutes, A count ratios of an anterior putamen to posterior one formed a plateau after 85 minutes. Conclusion The dynamic acquisition can be possible to evaluate a distribution of the $^{18}F-DOPA$ in the striatum and the VOI analysis through a dynamic acquisition and a variety of patterns. Futhermore, to make a uniformed distribution and count ratio of striatum to cerebellum, a static acquisition will have to start 90minutes later after injection.

• 대한핵의학회:학술대회논문집
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• 2005.11a
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• pp.345.2-345.2
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• 2005

• Korean Journal of Digital Imaging in Medicine
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• v.15 no.2
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• pp.25-30
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• 2013

The purpose of this study was to provide information about exhibits for nuclear energy in science museums. This analysed form and content of exhibits of science museums. The subjects were exhibits of 3 science museums; Seoul science park, Seoul national science museum, Gwachen national science museum. The research results were as follows: First, 3 science museums had similar methods of exhibits and types of explanations because of speciality of theme. 3 science museums had mostly fixed exhibit. Panel was the most types of explanations in 3 science museums. Second, 3 science museums had similar contents of exhibits. They dealt with nuclear power generation and radiation. However, Some parts such as radioactive waste, nuclear fusion generation had different. This study suggests that exhibits for nuclear energy of science museums use a variety of methods and types of explanation. Also, science museums need to increase exhibits for nuclear energy.

• Journal of radiological science and technology
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• v.37 no.4
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• pp.247-252
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• 2014

The medical institution has been used electromagnetic radiation of various energy. But researchers are divided on whether using apron for radiation shielding will be effective or not. The purpose of present study was to analyze electromagnetic radiation shielding effect of apron by using Monte carlo simulation. 1 MBq electromagnetic radiation was emitted from 10-500 keV at 10 keV increments in Monte carlo simulation. Then shielded radiation dose difference was confirmed, when 0.25 mmPb shield use for shielding. As a results, shielding ratio was markedly decreased in high energy electromagnetic radiation. The radiation dose was inversely increased with 0.25 mmPb shielding.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.96-99
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• 2004

The objective of this study is to assess attenuation correction algorithms utilized in a multipurpose whole-body GSO PET scanner. Four different types of phantoms were tested using different types of attenuation correction techniques. FOV (Field of View) of 256mm was used for brain PET imaging. For compensating attenuation, transmission data of a $^{137}$Cs point source were acquired after the F-18 emission source was infused to the phantoms. Scatter correction were peformed. Reconstructed images of the phantoms were assessed. In addition, reconstructed images of a normal subject were compared and assessed by nuclear medicine physicians. As a result, decreased intensity at the central portion of the attenuation map with cylindrical phantom was noticed during use of the measured attenuation correction. On the other hand, segmentation or remapping attenuation correction provided uniform phantom image. the images reconstructed from the clinical brain data explained the attenuation of a skull, at though reconstructed images of the phantoms couldn't explain it. in conclusion, the complicated and improved attenuation correction methods were required to obtain the better accuracy of the quantitative brain PET images. Our study will be useful in improving quantitative brain PET imaging modalities with attenuation correction of $^{137}$Cs transmission source.