• Progress in Medical Physics
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• v.20 no.1
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• pp.37-42
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• 2009

Proton therapy facility, which is recently installed at National Cancer Center in Korea, generally produces a large amount of radiation near cyclotron due to the secondary particles and radioisotopes caused by collision between proton and nearby materials during the acceleration. Although the level of radiation by radioisotope decreases in length of time, radiation exposure problem still exists since workers are easily exposed by a low level of radiation for a long time due to their job assignment for maintenance or repair of the proton facility. In this paper, the working environment near cyclotron, where the highest radiation exposure is expected, was studied by measuring the degree of radiation and its duration for an appropriate level of protective action guide. To do this, we measured the radiation change in the graphite based energy degrader, the efficiency of transmitted beam and relative activation degree of the transmission beam line. The results showed that while the level of radiation exposure around cyclotron and beam line during the operation is much higher than the other radiation therapy facilities, the radiation exposure rate per year is under the limit recommended by the law showing 1~3 mSv/year.

• Journal of Plant Biology
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• v.12 no.3
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• pp.26-34
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• 1969

Through immersing barley seeds (variety; Suwon No. 6) into different dilution of carrier-free P-32 original solution (Total activity; 90mc, To; 3/21) for 24 hours at room temperature, four groups of seeds (each group consists of 200 seeds) having activity levels of 1.6$\times$10-3$\mu$c 32P/grain, 2.3$\times$10-1$\mu$c 32P/grain 6.9$\times$100$\mu$c 32P/grain and 2.5$\times$101$\mu$c 32P/grain respectively, were obtained. To investigate the effects of various activity levels of P-32 absorbed upon the test plants, the seeds were germinated, transplant into the pots, and the growth was observed for three months after germination. After harvest, the inorganic contents in the leaves and the stems were also analyzed. The results: 1) Until four days after the beginning of germination, the rate of germination was found the lowest at the strongest activity level of 2.5$\times$101$\mu$c/grain. At the other P-32 levels treated, it showed generally higher than the control. 2) Before transplanting the seedlings of both 1.6$\times$103$\mu$c/grain and 2.3$\times$10-1uc/grain levels showed more vigorous growth than the control, whereas at the 6.9$\times$100 uc/grain level a retarded growth was conspicuous and all of plants belonging to the highest activity level of 2.5$\times$101$\mu$c/grain were withered owing apparently to the radiation damage. 3) This trend of growth promotion was continnually observed at the low activity levels even after transplanting the seeldings to the pots. As for the plants belonging to 6.9$\times$100$\mu$c/grain level, a clear sign of gradual recovery from the damage afflicted at the earlier stage was observable, and as a result the plants showed more growth than those of control two months after transplanting. 4) The number of stems diverged was found somewhat small in the blocks treated with P-32, compared with that of control until two months after germination. At the later stage of growth there seemed no significant difference among the themselves. 5) The dry weight of leaves and stems was proved that the lower the activity, the mroe it was produced. The relative increase of dry matter in each treatment compared with the control was 2% at 6.9$\times$105$\mu$c/grain level, 9% at 2.3$\times$10-1$\mu$c/grain and 35% at 1.6$\times$10-3$\mu$c/grain respectively. 6) The inorganic contents of the leaves and stems harvested were proved that: (1) Nitrogen was highest at the lowest activity level of 2.3$\times$10-1$\mu$c/grian. (2) Phosphorus showed generally higher contents in the treated blocks than in control, with the peak being at 2.3$\times$10-1$\mu$c/grain. (2) Phosphorus showed generally higher contents in the treated blocks than in contro, with the peak being at 2.3$\times$10-1$\mu$c/grain level in the leaves and at 6.9$\times$100$\mu$c/grain in the stems. (3) These was no significant difference in potassium contents in the leaves between treatment and control, whereas in the stem the treated blocks were higher than control roughly in propotion to the activity level. (4) Calcium in the lesves was richer in treated blocks than control while in the stem no difference was seen. (5) Magnesium contents both in leaves and in stems there was no difference among treatments.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.2
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• pp.74-79
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• 2017

Purpose Proton therapy can deliver an optimal dose to tumor while reducing unnecessary dose to normal tissue as compared the conventional photon therapy. As proton beams are irradiated into tissue, various positron emitters are produced via nuclear fragmentation reactions. These positron emitters could be used for the dose verification by using PET. However, the short half-life of the radioisotopes makes it hard to obtain the enough amounts of events. The aim of this study is to investigate the effect of off-line PET imaging scan time on the PET image quality. Materials and Methods The various diameters of spheres (D=37, 28, 22 mm) filled with distilled water were inserted in a 2001 IEC body phantom. Then proton beams (100 MU) were irradiated into the center of the each sphere using the wobbling technique with the gantry angle of $0^{\circ}$. The modulation widths of the spread out bragg peak were 16.4, 14.7 and 9.3 cm for the spheres of 37, 28 and 22 mm in diameters respectively. After 5 min of the proton irradiation, the PET images of the IEC body phantom were obtained for 50 min. The PET images with different time courses (0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min) were obtained by dividing the frame with a duration of 10 min. In order to evaluate the off-line PET image quality with the different time courses, the contrast-to-noise ratio (CNR) of the PET image calculated for each sphere. Results The CNRs of the sphere (D=37 mm) were 0.43, 0.42, 0.40, 0.31 and 0.21 for the time courses of 0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min respectively. The CNRs of the sphere (D=28 mm) were 0.36, 0.32, 0.27, 0.19 and 0.09 for the time courses of 0-10 min, 11-20 min, 21-30 min, 31-40 min and 41-50 min respectively. The CNR of 37 mm sphere was decreased rapidly after 30 min of the proton irradiation. In case of the spheres of 28 mm and 22 mm, the CNR was decreased drastically after 20 min of the irradiation. Conclusion The off-line PET imaging time is an important factor for the monitoring of the proton therapy. In case of the lesion diameter of 22 mm, the off-line PET image should be obtained within 25 min after the proton irradiation. When it comes to small size of tumor, the long PET imaging time will be beneficial for the proton therapy treatment monitoring.

• Radiation Oncology Journal
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• v.19 no.4
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• pp.369-380
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• 2001

Purpose : By developing on-line statistics program to record the information of radiation oncology to share the information with internet. It is possible to supply basic reference data for administrative plans to improve radiation oncology. Materials and methods : The information of radiation oncology statistics had been collected by paper forms about 52 hospitals in the past. Now, we can input the data by internet web browsers. The statistics program used windows NT 4.0 operation system, Internal Information Server 4.0 (IIS4.0) as a web server and the Microsoft Access MDB. We used Structured Query Language (SQL), Visual Basic, VBScript and JAVAScript to display the statistics according to years and hospitals. Results : This program shows present conditions about man power, research, therapy machines, technics, brachytherapy, clinic statistics, radiation safety management, institution, quality assurance and radioisotopes in radiation oncology department. The database consists of 38 inputs and 6 outputs windows. Statistical output windows can be increased continuously according to user's need. Conclusion : We have developed statistics program to process all of the data in department of radiation oncology for reference information. Users easily could input the data by internet web browsers and share the information.

• Journal of Chest Surgery
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• v.35 no.3
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• pp.171-176
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• 2002

Background: Blood-foreign interaction cause activation of coagulation and inflammatory process that may lead to multiorgan dysfunction and determine the surgical outcomes. Of the methods for assessing the biocompatibility, the platelet adhesion study is considered as the most valuable evaluation step in blood-foreign interaction. As the most studies have used in-vitro or ex-vivo conditions, we have developed a technique of quantification for platelet adhesion on the blood contact surface by using in-vivo injection of radioactive platelets. Material and Method: A coupled bypass circuit was designed to connect the proximal and descending thoracic aorta in 6 piglets(20∼25 Kg). One side of the circuit tube was consisted of a heparin coated PVC tube(10mm in ID, n=6, Experimental group), and the other, a non-heparin coated PVC tube(10mm in ID, n=6, Control group). After cannulation, the blood was circulated through the circuit for 2 hours. Platelet concentrate was prepared from homologous pig blood 24 hours before the experiment. The platelet concentrate was incubated with Tc-99m-HMPAO for 30 min and then centrifuged for 10 min. The supernatant was discarded and the radio-labeling efficacy was measured. The radio-labeled platelet concentrate was mixed with the autologous plasma to make the volume 5 ml, and the mixture was injected intravenously into the experimental animal. After 2 hour circulation, 5 pieces of the specimen(10mm in length each) were obtained from each PVC tube. The radioisotopes were counted with a gamma counter(Cobra ll, Packard, USA), and the ratio of radioisotope count was compared between the control and experimental group. Result: The radioisotope count number was 537.3221.1 Ci/min in the control group and 311.1 184.5 Ci/min in the experimental group(p=0.0104). The ratio between the groups was 1 to 0.58 (p=0.004). Conclusion: In vivo quantification using technetium-99m-HMPAO labeled platelets is simple and reproducible in evaluating platelet adhesion on a foreign surface. We suggest this technique to be a useful tool for blood compatibility test.

• The Korean Journal of Nuclear Medicine
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• v.28 no.1
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• pp.98-105
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• 1994

The search for tumor-avid agents for use in nuclear medicine imaging or therapy is a field of ongoing importance. Metallothionein (MT) is an intracellular protein that binds many metals with isotopes having imaging or radiotherapeutic potential. The purpose of the study was to determine whether uptake of radioisotopes that bind to MT is increased in tumor. We measured the uptake of Cd-109 and Ga-67 in tumor and normal tissues of sarcoma-bearing mice. Tumors were grown subcutaneously in female Balb/C mice from cultured Balb/3T3 cells transformed by the Moloney murine sarcoma virus (MMSV). When the tumors reached about 1 cm in diameter, mice were injected subcutaneously with Cd-109 and Ga-67. Eighteen and seventy-two hours later, the mice were sacrified. Organs and tissues were removed, weighed, and activity per mg tissue determined by gamma well-counting. Uptake of Cd-109 by MMSV tumors exceeded that by normal tissues examined, with the exception of liver and kidney (the organs known to be richest in MT). The tumor-to-tissue ratios of uptake for Cd-109 were far greater than those for Ga-67 for many normal tissues of great importance in terms of background activity (bone, intestine, fat, muscle, and blood). We concluded that metals that bind to MT may be useful for oncologic imaging or rediotherapy of cancer.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.13-20
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• 2008

The flow rate measurements in a multi-phase flow pipeline were evaluated quantitatively by means of a clamp-on sealed radioisotope based on a cross correlation signal processing technique. The flow rates were calculated by a determination of the transit time between two sealed gamma sources by using a cross correlation function following FFT filtering, then corrected with vapor fraction in the pipeline which was measured by the ${\gamma}$-ray attenuation method. The pipeline model was manufactured by acrylic resin(ID. 8 cm, L=3.5 m, t=10 mm), and the multi-phase flow patterns were realized by an injection of compressed $N_2$ gas. Two sealed gamma sources of $^{137}Cs$ (E=0.662 MeV, ${\Gamma}$ $factor=0.326\;R{\cdot}h^{-1}{\cdot}m^2{\cdot}Ci^{-1}$) of 20 mCi and 17 mCi, and radiation detectors of $2"{\times}2"$ NaI(Tl) scintillation counter (Eberline, SP-3) were used for this study. Under the given conditions(the distance between two sources: 4D(D; inner diameter), N/S ratio: $0.12{\sim}0.15$, sampling time ${\Delta}t$: 4msec), the measured flow rates showed the maximum. relative error of 1.7 % when compared to the real ones through the vapor content corrections($6.1\;%{\sim}9.2\;%$). From a subsequent experiment, it was proven that the closer the distance between the two sealed sources is, the more precise the measured flow rates are. Provided additional studies related to the selection of radioisotopes their activity, and an optimization of the experimental geometry are carried out, it is anticipated that a radioisotope application for flow rate measurements can be used as an important tool for monitoring multi-phase facilities belonging to petrochemical and refinery industries and contributes economically in the light of maintenance and control of them.

• Journal of Radiation Protection and Research
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• v.33 no.2
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• pp.77-86
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• 2008

This study attempted to provide reference materials for improving the behavior level in radiation safety managements by drawing a prediction model that affects the radiation safety management behavior because the radiation safety management of medical Cyclotrons, which can be used to produce radioisotopes, is an important factor that protects radiation caused diseases not only for radiological operators but average users. In addition, this study obtained follows results through the investigation applied from January 2 to January 30, 2008 for the radiation safety managers employed in 24 authorized organizations, which have already installed Cyclotrons, through applying a specific form of questionnaire in which the validity was guaranteed by reference study, site investigation, and focus discussion by related experts. The radiation safety management were configured as seven steps: Step 1 is a production preparation step, Step 2 is an RI production step, Step 3 is a synthesis step, Step 4 is a distribution step, Step 5 is a quality control step, Step 6 is a carriage container packing step, and Step 7 is a transportation step. it was recognized that the distribution step was the most exposed as 15 subjects (62.5%), the items of 'the sanction and permission related works' and 'the guarantee of installation facilities and production equipments' were the most difficult as 9 subjects (37.5%), and In the trouble steps in such exposure, the item of 'the synthesis and distribution' steps were 4 times, respectively (30.8%). In the score of the behavior level in radiation safety managements, the minimum and maximum scores were 2.42 and 4.00, respectively, and the average score was $3.46{\pm}0.47$ out of 4. Prosperity and well-being programs in the behavior and job in radiation safety managements (r=0.529) represented a significant correlation statistically. In the drawing of a prediction model based on the factors that affected the behavior in radiation safety managements, general characteristics, organization characteristics, and selfefficacy didn't show a significant path statistically in which the prosperity and well-being programs in job characteristics affected the behavior in radiation safety managements. Therefore, it is necessary to establish a strategy that improves the level of prosperity and well-being levels in job characteristics in order to increase the behavior in radiation safety managements. Thus, this study provides basic materials for the radiation safety management of Cyclotron through the full-scale investigation that is first applied in Korea.

• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.45-52
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• 2024

In this study, an AI-based algorithm was developed to prevent image quality deterioration and reading errors due to patient movement in PET/CT examinations that use radioisotopes in medical institutions to test cancer and other diseases. Using the Mothion Free software developed using, we checked the degree of correction of movement due to breathing, evaluated its usefulness, and conducted a study for clinical application. The experimental method was to use an RPM Phantom to inject the radioisotope 18F-FDG into a vacuum vial and a sphere of a NEMA IEC body Phantom of different sizes, and to produce images by directing the movement of the radioisotope into a moving lesion during respiration. The vacuum vial had different degrees of movement at different positions, and the spheres of the NEMA IEC body Phantom of different sizes produced different sizes of lesions. Through the acquired images, the lesion volume, maximum SUV, and average SUV were each measured to quantitatively evaluate the degree of motion correction by Motion Free. The average SUV of vacuum vial A, with a large degree of movement, was reduced by 23.36 %, and the error rate of vacuum vial B, with a small degree of movement, was reduced by 29.3 %. The average SUV error rate at the sphere 37mm and 22mm of the NEMA IEC body Phantom was reduced by 29.3 % and 26.51 %, respectively. The average error rate of the four measurements from which the error rate was calculated decreased by 30.03 %, indicating a more accurate average SUV value. In this study, only two-dimensional movements could be produced, so in order to obtain more accurate data, a Phantom that can embody the actual breathing movement of the human body was used, and if the diversity of the range of movement was configured, a more accurate evaluation of usability could be made.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.31-36
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• 2013

Purpose: Measure gastric emptying time (GET: Gastric Emptying Time) is a non-invasive and quantitative evaluation methods, mainly by endoscopic or radiological examination confirmed no mechanical obstruction in patients with symptoms of congestion is checked. Such tests are not common gastric emptying time measured esophageal cancer patients (who underwent esophagectomy) patients after surgery for gastric emptying time was measured test. And the period of time for more than one year after the gastric emptying time measurement was performed. By comparing the two kinds of tests in the chest cavity after surgery as the evaluation of gastrointestinal function tests evaluate the usefulness of GET, and will evaluate the characteristics of the image. Materials and Methods: 93 patients who underwent esophagectomy with gastric emptying time measurement of subject tests immediately after surgery and after 1 year or longer were twice. Preparation of the patient before the test is more than 12 hours of overnight fasting is important, in addition to the medicine or to stop smoking, and diabetes insulin injections should be early in the morning is ideal to test. Generally labeled with $^{99m}Tc-DTPA$ resin which is used to make steamed egg, seaweed and fermented milk with a high viscosity after eating, three hours in the standing position was measured. Evaluation of gastric emptying curves on the way intragastric radioactivity level by 50% the time (half-time [T1/2]) was calculated, based on the half-life was divided into three steps: over 180 minutes was defined as delayed gastric emptying, within 180minutes was defined as intermediate gastric emptying and when all the radioisotopes were dumped into the jejunum as soon as swallowed, was defined as rapid gastric emptying. Results: Gastric emptying time of a typical images stomach of antrum and fundus additional images appear stronger over time move on to the small intestine. but esophageal cancer who underwent esophagectomy side of the thoracic cavity showed a strong image. Immediately after surgery, the half-time (T1/2) of rapid gastric emptying appeared to 12.9%, intermediate gastric emptying appeared to 52.7%, delay gastric emptying appeared to 34.4%. After more than a year the results of the half-life after surgery, 67% of rapid gastric emptying to intermediate gastric emptying was changed, 69% of delay gastric emptying to intermediate gastric emptying changed. Intermediate gastric emptying worse in patients rapid gastric emptying and the delay gastric emptying is 24% in the case. Conclusion: Esophagectomy for esophageal cancer who underwent half-time measurement test (T1/2) rapid gastric emptying and delay gastric emptying are the result of the comparison over time, changes were observed intermediate gastric emptying. Mainly seeing of gastric emptying time measurement in the esophagus instead of thoracic cavity to check the evaluation of gastrointestinal function can be useful even means. And segmentation criteria and narrow time interval of checking if more accurate information and analysis of the clinical diagnosis and evaluation seems to be done.