• Journal of the Korean Society of Radiology
• /
• v.14 no.2
• /
• pp.77-83
• /
• 2020

This study investigated the radiation protection of therapeutic radiologists. Based on the change in X-ray energy and MU value, the space dose rate in the treatment room after the irradiation was measured. 6MV, 10MV and 15MV photon beams were exposed to radiation inside the treatment room based on 300MU, 600MU and 1000MU using a linear accelerator. And repeated 10 times under the same conditions. As a result of the experiment, 0.1555 μSv/h for 6MV 300MU, 0.157 μSv /h for 300sec, 0.152 μSv/h, 0.156 μSv/h for 600MU, and 0.157 μSv/h 0.152 μSv/h for 1000MU. 300MU of 10MV was 0.49 μSv/h, 0.309 μSv/h, and 0.69 μSv/h, 0.416 μSv/h for 600MU, respectively, and 1000MU was 0.977 μSv/h and 0.478 μSv/h, respectively. The 300MU of 15MV was 3.02 μSv/h, 1.2 μSv/h, 5.459 μSv/h at 600MU, 7.34 μSv/h at 1.836 μSv/h 1000MU, and 2.709 μSv/h. The average spatial dose rate of 6MV was not significantly different from the natural spatial dose rate in the treatment room. High spatial dose rates were measured at 10 MV and 15 MV and were attenuated over time. Therefore, entering the treatment room after a certain period of time (more than 60 seconds) is considered to be effective to prevent the exposure dose of radiation workers.

• Journal of the Korean Society of Radiology
• /
• v.14 no.1
• /
• pp.23-29
• /
• 2020

The standard uptake values (SUVs) strongly depend on positron emission tomographs (PETs) and image reconstruction methods. Various image reconstruction algorithms in GE Discovery MIDR (DMIDR) and Discovery Ste (DSte) installed at Department of Nuclear Medicine, Seoul Samsung Medical Center were applied to measure the SUVs in an anthropomorphic torso phantom. The measured SUVs in the heart, liver, and background were compared to the actual SUVs. Applied image reconstruction algorithms were VPFX-S (TOF+PSF), QCFX-S-350 (Q.Clear+TOF+PSF), QCFX-S-50, VPHD-S (OSEM+PSF) for DMIDR, and VUE Point (OSEM) and FORE-FBP for DSte. To reduce the radiation exposure to radiation technologists, only the small amount of radiation source ¹⁸F-FDG was mixed with the distilled water: 2.28 MBq in the 52.5 ml heart, 20.3 MBq in the 1,290 ml liver and 45.7 MBq for the 9,590 ml in the background region. SUV values in the heart with the algorithms of VPFX-S, QCFX-S-350, QCFX-S-50, VPHD-S, VUE Point, and FOR-FBP were 27.1, 28.0, 27.1, 26.5, 8.0, and 7.4 with the expected SUV of 5.9, and in the background 4.2, 4.1, 4.2, 4.1, 1.1, and 1.2 with the expected SUV of 0.8, respectively. Although the SUVs in each region were different for the six reconstruction algorithms in two PET/CTs, the SUV ratios between heart and background were found to be relatively consistent; 6.5, 6.8, 6.5, 6.5, 7.3, and 6.2 for the six reconstruction algorithms with the expected ratio of 7.8, respectively. Mean SNRs (Signal to Noise Ratios) in the heart were 8.3, 12.8, 8.3, 8.4, 17.2, and 16.6, respectively. In conclusion, the performance of PETs may be checked by using with the SUV ratios between two regions and a relatively small amount of radioactivity.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.1
• /
• pp.17-24
• /
• 2011

Purpose: Presently in the nuclear medicine field, the high-speed image reconstruction algorithm like the OSEM algorithm is widely used as the alternative of the filtered back projection method due to the rapid development and application of the digital computer. There is no to relate and if it applies the optimal parameter be clearly determined. In this research, the quality change of the Jaszczak phantom experiment and brain SPECT patient data according to the iteration times and subset number change try to be been put through and analyzed in 3D OSEM reconstruction method of applying 3D beam modeling. Materials and Methods: Patient data from August, 2010 studied and analyzed against 5 patients implementing the brain SPECT until september, 2010 in the nuclear medicine department of ASAN medical center. The phantom image used the mixed Jaszczak phantom equally and obtained the water and 99mTc (500 MBq) in the dual head gamma camera Symbia T2 of Siemens. When reconstructing each image altogether with patient data and phantom data, we changed iteration number as 1, 4, 8, 12, 24 and 30 times and subset number as 2, 4, 8, 16 and 32 times. We reconstructed in reconstructed each image, the variation coefficient for guessing about noise of images and image contrast, FWHM were produced and compared. Results: In patients and phantom experiment data, a contrast and spatial resolution of an image showed the tendency to increase linearly altogether according to the increment of the iteration times and subset number but the variation coefficient did not show the tendency to be improved according to the increase of two parameters. In the comparison according to the scan time, the image contrast and FWHM showed altogether the result of being linearly improved according to the iteration times and subset number increase in projection per 10, 20 and 30 second image but the variation coefficient did not show the tendency to be improved. Conclusion: The linear relationship of the image contrast improved in 3D OSEM reconstruction method image of applying 3D beam modeling through this experiment like the existing 1D and 2D OSEM reconfiguration method according to the iteration times and subset number increase could be confirmed. However, this is simple phantom experiment and the result of obtaining by the some patients limited range and the various variables can be existed. So for generalizing this based on this results of this experiment, there is the excessiveness and the evaluation about 3D OSEM reconfiguration method should be additionally made through experiments after this.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.1
• /
• pp.58-64
• /
• 2011

Objective: The 3-dimensional reconstruction method with resolution recovery modeling has advantages of high spatial resolution and contrast because of its precise modeling of spatial blurring according to the distance from detector plane. The aim of this study was to evaluate one of the resolution recovery reconstruction methods (Astonish, Philips Medical), compare it to other iterative reconstructions, and verify its clinical usefulness. Materials and Methods: NEMA IEC PET body phantom and Flanges Jaszczak ECT phantom (Data Spectrum Corp., USA) studies were performed using Skylight SPECT (Philips) system under four different conditions; short or long (2 times of short) radius, and half or full (40 kcts/frame) acquisition counts. Astonish reconstruction method was compared with two other iterative reconstructions; MLEM and 3D-OSEM which vendor supplied. For quantitative analysis, the contrast ratios obtained from IEC phantom test were compared. Reconstruction parameters were determined by optimization study using graph of contrast ratio versus background variability. The qualitative comparison was performed with Jaszczak ECT phantom and human myocardial data. Results: The overall contrast ratio was higher with Astonish than the others. For the largest hot sphere of 37 mm diameter, Astonish showed about 27.1% and 17.4% higher contrast ratio than MLEM and 3D-OSEM, in short radius study. For long radius, Astonish showed about 40.5% and 32.6% higher contrast ratio than MLEM and 3D-OSEM. The effect of acquired counts was insignificant. In the qualitative studies with Jaszczak phantom and human myocardial data, Astonish showed the best image quality. Conclusion: In this study, we have found out that Astonish can provide more reliable clinical results by better image quality compared to other iterative reconstruction methods. Although further clinical studies are required, Astonish would be used in clinics with confidence for enhancement of images.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.1
• /
• pp.117-120
• /
• 2011

Purpose: There are 3 warnings for Glucagon tests. First, EDTA tubes that already contain Aprotinin must be used for plasma collection. Second, for freezer storage of centrifuged plasma, glass tubes must be used. Last, glass tubes must be used for testing procedure. So we compared the glucagon results of next 3 situation to those of control group. First, We compared to results by tubes without Aprotinin and with aprotinin. Second, we compared to results by tubes(plastic vs glass) for plasma storage. Third, we compared to results by tubes(plastic vs glass) for testing. We tried to evaluate the results of the 3 different condition. Materials and Methods: 40 healthy adults were studied with normal results on the general medical check up and laboratory tests. We compared the results of 3 different condition belows: Blood were collected in EDTA tube containing aprotinin and plasma was stored in the glass tube for 3 days in a freezer and results were obtained by tests in the glass tubes. Results from EDTA plasma without aprotinin, results from platic tubes for freezer stroage, results from plastic tube when testing. Simple linear regression analysis and paired t-test using SPSS were done for statistical analysis. Commercial glucagon kit(RIA-method)which made by Siemens company were used. Results: Correlation coefficient between results of EDTA tubes with Aprotinin vs without Aprotinin was r=0.783 (p=0.064). Result of specimen in plastic tubes stored 3 days in a freezer showed lower value compared to those in glass tube(r=0.979, p=0.005). Also, results of testing in plastic tubes showed lower values than those testing in glass tubes. (r=0.754, p<0.001). Conclusion: It is recommended for glucagon determination to use EDTA tube with Aprotinin which is a inhibitor of protein breakdown enzyme. Results of plastic tube when storage and testing showed lower value than those of glass tubes, so it is recommended to store and test in glass tubes.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.15 no.1
• /
• pp.113-116
• /
• 2011

Purpose: Acetylcholine receptor antibodies cause acetylcholine receptor loss, which is responsible for failure of the neuromuscular junction in the acetylcholine receptor autoantibody. The disease characterized by muscle weakness and fatigue, myasthenia gravis(MG) occurs when the body inappropriately produces antibodies against acetylcholine receptors, and thus inhibits proper acetylcholine signal transmission. And this reason, the measurement of acetylcholine receptor antibodies can be of considerable value in disease diagnosis. Methods: From 2010. August to September, we tested orderd AchRAb 19 samples to get the results. 1. Pipette $5{\mu}{\ell}$ undiluted patient sera and kit control and add 125I AChR $50{\mu}{\ell}$ and incubate at R.T for 2 hours. 2. Pipette $50{\mu}{\ell}$ of anti-human IgG into each tube, and incubate at $2{\sim}8^{\circ}C$ for 2 hours. 3. Pipette $25{\mu}{\ell}$ precipitation enhancer into each tube and add 1mL washing solution into all tubes. 4. Centrifuge each tube for 20minutes at $2{\sim}8^{\circ}C$ at 1500g. 5. Aspirate or decant the supernatant. 6. Pipette 1 mL washing solution into all tubes and resuspend the pellet and repeat centrifugation. 7. Aspirate or decant the supernatant and count all tubes on a gamma counter. Results: Cut off value is 0.2 nmol/L and the results taken below 0.2 nmol/L are negative, the results above that identified as being positive values. We assayed the 19 patients samples and got 7 positive results. Of which, 6 patients were diagnosed as MG.(85.7%). Conclusions: Acetylcholine Receptor autoantibody test is intended for use by persons only for the quantitative determination of it in human serum. Even if measurement of the antibodies is not a routine test, it can be of considerable value in disease diagnosis.

• The Korean Journal of Nuclear Medicine
• /
• v.30 no.4
• /
• pp.484-492
• /
• 1996

To detect ischemic tissue in experimental model of cerebral ischemia made by middle cerebral artery(MCA)-occlusion, we acquired triple image of $^{99m}Tc$-glucarate, [$^{18}F$]fluoro-deoxyglucose (FDG), and 2,3,5- triphenyltetrazolium (TTC) staining. We made cerebral infarction either with reperfusion (after occlusion of 2 hours) or without reperfusion in 10 Sprague-Dawley rats by inserting thread to MCA through internal carotid artery. After 22 hours, we injected 740 MBq of $^{99m}Tc$-glucarate and 55.5 MBq of [$^{18}F$]FDG through tail vein. Each 1 mm slice of rat brains was frozen and exposed to imaging plate for 20 minutes in freezer to get an [$^{18}F$]FDG image. After 20 hours enough to fade radioactivity of [$^{18}F$]FDG, the slices were again imaged by BAS1500 for $^{99m}Tc$-glucarate uptake. Finally, these brain tissues were stained with TTC. Semi-quantitative visual analysis was done by grading 0 to 3 points according to the degree of uptakes($^{99m}Tc$-glucarate) and decreased uptakes([$^{18}F$]FDG and TTC). Ten rats survived with neurologic symptoms. TTC staining confirmed the development of infarction. The size of the infarction was relatively larger in the group without reperfusion. [$^{18}F$]FDG images were similar to TTC-stained images. However, we found regions with intermediate uptake which were not stained with TTC. We found regions with intermediate [$^{18}F$]FDG uptake where TTC staining was normal. $^{99m}Tc$-glucarate uptake was round only in TTC non-stained region. In the TTC stained regions, there were no uptake of $^{99m}Tc$-glucarate. We could not find clear relation between $^{99m}Tc$-glucarate uptake with [$^{18}F$]FDG uptake. This was partly because percent uptake of $^{99m}Tc$-glucarate was so small (less than 1 percent of injected dose) and because there were quite heterogeneity of patterns of [$^{18}F$]FDG uptake and TTC. With these findings, we could conclude that $^{99m}Tc$-glucarate were taken up only in part of ischemic tissues which were proven to be nonviable. The establishment of MCA-occluded rat model with or without reperfusion and triple imaging for $^{99m}Tc,\;^{18}F$ and TTC helped the characterization of $^{99m}Tc$-glucarate uptakes. Further work is needed to clarify the meaning or diversities or [$^{18}F$]FDG and TTC and their relation with $^{99m}Tc$-glucarate.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.18 no.1
• /
• pp.127-133
• /
• 2014

Purpose: Low dose of PET/CT is important because of Patient's X-ray exposure. The aim of this study was to evaluate the effectiveness of low-dose PET/ CT image through the CTAC and QAC of patient study and phantom study. Materials and Methods: We used the discovery 710 PET/CT (GE). We used the NEMA IEC body phantom for evaluating the PET data corrected by ultra-low dose CT attenuation correction method and NU2-94 phantom for uniformity. After injection of 70.78 MBq and 22.2 MBq of 18 F-FDG were done to each of phantom, PET/CT scans were obtained. PET data were reconstructed by using of CTAC of which dose was for the diagnosis CT and Q. AC of which was only for attenuation correction. Quantitative analysis was performed by use of horizontal profile and vertical profile. Reference data which were corrected by CTAC were compared to PET data which was corrected by the ultra-low dose. The relative error was assessed. Patients with over weighted and normal weight also underwent a PET/CT scans according to low dose protocol and standard dose protocol. Relative error and signal to noise ratio of SUV were analyzed. Results: In the results of phantom test, phantom PET data were corrected by CTAC and Q.AC and they were compared each other. The relative error of Q.AC profile was been calculated, and it was shown in graph. In patient studies, PET data for overweight patient and normal weight patient were reconstructed by CTAC and Q.AC under routine dose and ultra-low dose. When routine dose was used, the relative error was small. When high dose was used, the result of overweight patient was effectively corrected by Q.AC. Conclusion: In phantom study, CTAC method with 80 kVp and 10 mA was resulted in bead hardening artifact. PET data corrected by ultra- low dose CTAC was not quantified, but those by the same dose were quantified properly. In patients' cases, PET data of over weighted patient could be quantified by Q.AC method. Its relative difference was not significant. Q.AC method was proper attenuation correction method when ultra-low dose was used. As a result, it is expected that Q.AC is a good method in order to reduce patient's exposure dose.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.1
• /
• pp.159-165
• /
• 2018

In recent years, universal design concepts have been introduced that are designed to make everybody more comfortable and safe to use for products, buildings, environments, services, and so on. In the case of urban railroad history, it is important to maintain facilities that incorporate the universal design concept because it is an important facility that serves as a base of city life and there are various users. This research is the last annual task of 5 years as part of the project of "Development of Technique to Improve the Convenience of Urban Railway History User" by the National Institute of Transportation Technology Promotion Agency. The purpose of this study is to develop criteria and method of facilities convenience evaluation based on UD and to evaluate user convenience by selecting test bed station. For this purpose, the UD principle of the historic facilities of Weihai Urban Railway was established and detailed evaluation criteria were presented. As a result of evaluating the test bed history using the 5-point Likert scale of the joint research institute / railway operating agency / expert, 50.3% of convenience improvement was achieved. As a result of evaluating the applicability according to the UD principle, 48.7% Respectively. The evaluation criteria and methodology based on the UD suggested in this study is a quantitative method for evaluating UD application of urban railway facilities in the future.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.8 no.1
• /
• pp.31-40
• /
• 2005

Purpose: This study aimed to provide, as a basic material, the experiences of endoscopy in diagnosis and treatment of tumorous conditions in the upper gastrointestinal tract in children. Methods: The objects were 26 patients diagnosed as having tumorous conditions in the upper gastrointestinal tract among 1,283 patients who underwent upper gastrointestinal endoscopic examination at the Department of Pediatrics, Pusan National University Hospital, from January 1994 to July 2004 retrospectively. The characteristics of patients, the chief complaints for endoscopic examination, the sorts of tumors diagnosed, the endoscopic findings of tumors, and the treatment of tumors were analysed. Results: 1) Eleven male and fifteen female were included, whose mean age was $6.93{\pm}4.02years$. 2) The chief complaints for endoscopic examination were abdominal pain (80.7%), vomiting or nausea (30.8%), and gastrointestinal beeding (30.7%) in order. 3) Six cases of ectopic pancreas, five cases of sentinel polyp, three cases of papilloma and vallecular cyst, two cases of Brunner's gland hyperplasia and gastric submucosal tumor, one case of gastrointestinal stromal tumor, duodenal intramural hematoma, T cell lymphoma, lipoma, and Peutz-Jeghers syndrome were diagnosed by endoscopy with or without biopsy. 4) The location of tumors was in the pharynx (19.2%), esophagus (7.7%), gastro-esophageal junction (23.0%), stomach (30.7%) and duodeneum (26.9%). 5) The size of tumors was less than 10 mm in 53.8%, 10~20 mm in 26.9%, more than 20 mm 19.2%. 6) Treatments for tumors included resection by laser, surgical resection, endoscopic polypectomy with a forcep or snare, and observation 7) There was no significant complication. Conclusion: Various and not a few tumors were found in the upper gastrointestinal tract. The endoscopy was accurate, effective, and safe means for diagnosis and treatment of those lesions in children.