• Economic and Environmental Geology
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• v.29 no.2
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• pp.215-225
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• 1996

All the radionuclides in high-level nuclear waste will decay to harmless levels eventually but for some radionuclides decay is so slow that their radiation remains dangerous for times on the order of tens or hundreds of thousands of years. At the present time, the most favorite disposal plan for high-level radioactive waste is a mined geological disposal in which canister enclosing stable solid form of radioactive waste is placed in mined cavities locating hundred meters below the surface. The chief hazard in such disposal is dissolution of radionuclides from the waste in the groundwater that will eventually carry the dissolved radionuclides to surface environments. The hazard from possible escape of the radionuclides through groundwater can be delayed by engineered and geologic barriers. The engineered barriers can become useless by unexpected geologic catastrophe such as volcanism, earthquake, and tectonic movement and by fraudulent work such as careless construction, improperly welded canisters within the first few decades or centuries. As a result, dangerously radioactive waste which is still intensively radioactive is directly exposed to attack by moving groundwater. All the more, it is almost impossible to control repositories for times more than 10,000 years. Therefore, naturally controlled geologic, barriers whose properties will not be changed within 10,000 years are important to guarantee the safety of repositories of high-level radioactive waste. In Sweden and France, the suitability of granite for the mined geological disposal of high-level waste has been studied intensively. According to the research in Sweden and France, granites has the following physio-chemical characteristics which can delay the transportation of radionuclide by groundwater. First, the permeabilities of granites decreases as the depth increases and is $10^{-8}{\sim}10^{-12}m/s$ at depth below 300 m. Second, groundwater at depth below 300 m has pH=7-9 and reducing condition (Eh=-0.1~0.4). This geochemical condition is desirable to prevent both canister and solid waste from corrosion. Third most radionuclides are not transported by low solubilities and some radionuclide with high solubility such as Cs and Sr are retarded by absorption of geologic media through which ground water flows. Therefore, if high-level waste is disposed at depth below 300 m in the granite body which has a low permeability and is geologically stable more than 10,000 years, the safety of repositories from the hazard due to radionuclide escape can guaranteed for more than 10,000 years.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.2
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• pp.171-182
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• 1990

The purpose of this study was to investigate the effects of irradiation on the striated duct cells of the rat submandibular gland ductal tissues which control the characteristics of saliva. For this study, the experimental group was composed of 36 irradiated Sprague Dawley strain rats divided into 8 subgroups 1 hour, 2 hours, 3 hours, 6 hours, 12 hours, 24 hours, 48 hours, 72 hours after irradiation. 4 non-irradiated rats were used as the control group. The experimental animals were singly irradiated with a dose of 18Gy gamma ray to their head and neck region by the Co-6- teletherapy unit and sacrificed after each experimental duration. The specimens were examined with a light microscope with an H-E stain and with a trans- mission electron microscope. The results of this study were as follows. In the light micrograph, a severe atrophic change occurred in the striated duct cells at 2hours after irradiation and gradual recovery occurred from 6 hours after irradiation. 2. The nuclear chromosomes of the striated duct cells were changed granular at 2 hours after irradiation. Recovery was observed at 6 hours after irradiation. Nuclear bodies were also observed from 3 hours after irradiation. 3. The mitochondria of the striated duct cells had indistinct cristae at 2 hours after irradiation, and were degenerated or swollen at 3 hours after irradiation. They recovered, however, from 6 hours, with an increasing number at 48 hours and a regular arrangement was observed at 72 hours after irradiation. 4. The microvilli showed atrophic changes at 2 hours after irradiation and were almost lost at 3 hours after irradiation. They were observed again from 48 hours after irradiation. 5. The rough endoplasmic reticulum and golgi body were not apparent at 1 hour after irradiation and were dilated with degeneration 2 hours after, but intact rough endoplasmic reticulum were observed from 3 hours after irradiation and developed well at 24 hours after irradiation. By the result of this study, showing a mild change in the functional morphology of the salivary striated duct cells immediately following irradiation, it is considered that the many complications which occur after radiation therapy, will disappear in time with the histological and the functional recovery of the glandular tissues.

• The Korean Journal of Nuclear Medicine
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• v.23 no.2
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• pp.219-223
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• 1989

Inflammation scan using radiolabelled leukocytes has high sensitivity and specificity. Several methods for labelling leukocytes have been evaluated using P-32 diisopropyl fluorophosphate (DFP-32), H-3 thymidine, Cr-51 chromate, Ga-67 citrate and Tc-99m-sulfur colloid. In-111-oxine has proved so far to be the most reliable agent for labelling leukocytes. In-111-oxine is, however, expensive, not easily available when needed, and its radiation dose to leukocytes is relatively high. Moreover, resolution of the resultant image is relatively poor. Tc-99m is still the agent of choice because of, as compared with the indium, its favorable physical characteristics, lower cost and availability. Now the technique for labelling the leukocytes with technetium is successfully obtained using the lipophilic HAPAO with higher efficiency for granulocytes than for other cells. With this technique it is possible to label leukocytes in plasma to improve the viability of the leukocytes. Inflammation scan using Tc-99m-HMPAO has been evaluated in several laboratories, and difference in methods for separation and labelling accounts for difference in efficiency, viability and biodistribution of the labelled leukocytes. We performed inflammation scan using leukocytes labelled with Tc-99m-HMPAO in three dogs 24 hours after inoculation of live E. Coli and A. Aureus in their right abdominal wall. We separated mixed leukocytes by simple sedimentation using 6% hetastarch (HES) and labelled the leukocytes with Tc-99m-HMPAO in 20% cell free plama diluted with phosphate buffer solution(Fig. 1). Uptake was high in the liver and spleen but is was minimal in the lungs on whole body scan. Kidneys and intestine showed minimal activity although it was high in the urinary bladder(Fig. 2). Uptake of labelled leukocytes in the inflammation site was do(mite on 2 hour-postinjection scan and abscess was clearly delineated on 24 hour-delayed scan with high target-to-nontarget ratio(Fig. 3, 4). Inflammation scan using mixed leukocytes labelled with Tc-99m-HMPAO is very sensitive and specific in early detection of inflammation.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.331-336
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• 2015

Medical electrical equipment - Part 1: General requirement for basic safety and essential performance of MFDS was revised as 3th edition and Medical electrical equipment Part 2-54: Particular requirements for the basic safety and essential performance of X-ray equipment will be expected to be announced as notification. Therefore this technical report was written to introduce provision of the particular requirements, replacement, addition, amendment. The purpose of this particular requirements is to secure requirements for basic safety and essential performance of X-ray equipment for radiography and radioscopy. X-ray high voltage generator, mechanical protective device, protection against radiation is included in this particular requirements. Medical electrical equipment - Part 1, Part 1-2, Part 1-3 is applied to this particular requirements. If the requirements is announced as notification, It is expected to widen understanding for basic safety and essential performance of X-ray equipment for radiography and radioscopy and play a part to internationalize of medical equipments.

• Journal of Sensor Science and Technology
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• v.6 no.5
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• pp.385-391
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• 1997

An objection of this study is to develop a measuring circuit of a gauge using radioisotope for compaction control. The gauge developed in this study makes use of radioisotope with the activity exempted from domestic atomic law and consists of measuring circuits for gamma-rays and thermal neutrons, a high voltage supply unit, and a microprocessor. To obtain meaningful numbers of pulse counts, parallel five and two circuits are provided for gamma-rays and thermal neutrons, respectively. Being simple in electrical characteristics of G-M detector for gamma-rays, pulses are counted through only a shaping circuit. Very small pulses generated from He- 3 proportional detector for thermal neutrons are amplified to the maximum of 50 [dB] and a window comparator accepts only pulses with meaning. To minimize effects of natural environmental radiation and electrical noise, circuits are electrostatically shielded and pulses made by ripples are eliminated by taking frequency of high voltage supplied to the circuit and pulse height of ripples into consideration. One-chip microprocessor is applied to process various counts, results are stored and the gauage is made capable to communicate with PC. Enough and meaningful numbers of pulses are counted with the prototype gauage for compaction control.

• The Korean Journal of Nuclear Medicine
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• v.8 no.1_2
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• pp.29-37
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• 1974

The $^{99m}Tc$-pertechnetate thyroid uptake rates(20 min) were measured in 24 healthy normal subjects, 140 patients with nontoxic goiter and 98 patients with thyrotoxicosis who were treated at the Thyroid Clinic, Seoul National University Hospital, from August 1972 to August 1973. Diagnostic reliabilities and correlations between $^{99m}TcO_4$-thyroid uptake rate (20 min) and other thyroid function tests were evaluated. The observed results were as follows 1. The $^{99m}TcO_4$-thyroid uptake rates (20 min) in normal subjects, euthyroid group and hyperthyroid group were $4.1{\pm}0.9%,\;5.2{\pm}1.8%\;and\;29.7{\pm}10.6%$. There was a significant difference between the mean of the euthyroid group and the mean of the hyperthyroid group and so differentiation between them can be easy. 2. In the diagnosis of hyperthyroidism, the reliabilities of $^{99m}TcO_4$- thyroid uptake rate(20 min), $^{131}I$ thyroid uptake rate(24hrs), serum $T_3$ resin uptake rate, serum $T_4\;and\;T_7\;were\;87.9{\sim}97.9%,\;81.2{\sim}94.4%,\;87.9{\sim}97.9%,\;90.5{\sim}99.3%\;and\;93.7{\sim}100%$. $^{99m}TcO_4$-thyroid uptake rate(20 min) is more accurate than $^{131}I$ thyroid uptake rate (24 hrs) in the diagnosis of hyperthyroidism. 3. $^{99m}TcO_4$-thyroid uptake rate (20 min) was well correlated with $^{131}I$ thyroid uptake rate (24 hrs), serum $T_3$ resin uptake rate, serum $T_4\;and\;T_7$. Points in favor of $^{99m}Tc$ are that it gives a small radiation dose to the thyroid, that tests can be repeated at the short interval, the study can be completed at a single patient visit and it is particularly well suited for the assessment of thyroid function in patients being treated with an antithyroid drug.

• The Korean Journal of Nuclear Medicine
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• v.26 no.1
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• pp.14-25
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• 1992

Thallium-201 $(^{201}T1)$ SPECT studies were performed on a normal volunteer and 12 patients with intracerebral lesions: 3 patients with gliomas, 3 patients with meningiomas, 1 patient each with metastatic tumor, brain abscess, and cerebral infarction, and 3 postirradiation patients. (2 with metastatic tumors, 1 with lymphoma). A $^{201}T1$ index, based on the ratio of $^{201}T1$ uptake in the brain lesion versus the homologous contralateral brain, was calculated and compared with tumor histology and CT/MRI findings. The SPECT $^{201}T1$ scan showed minimal uptake of tracer in a normal brain. There was substantial uptake of $^{201}T1$ in high-grade gliomas (index>1.5) with little uptake in low-grade lesions. A previously irradiated patient with recurrent astrocytoma, in whom MRI study was unable to distinguish tumor recurrence from necrosis, showed the lesions with high $^{201}T1$ indices in both hemispheric regions (2.50/1.93), suggesting tumor recurrence. Two meningiomas and a metastatic tumor showed varying degrees of $^{201}T1$ uptake (index $1.71\sim8.15$), revealing that $^{201}T1$ uptake is not exclusive to high-grade gliomas. In 2 postirradiation patients with metastatic tumors, no abnormal $^{201}T1$ uptake was found in the cerebral lesions, shortly after the initiation of radiation therapy or despite the persistence of enhancing lesions-though improved-on MR images, suggesting that $^{201}T1$ uptake may reflect the metabolic and possibly clonogenic activities of tumors and the brain $^{201}T1$ SPECT imaging might be valuable for the evaluation of tumor responsiveness to the therapy and for early detection of tumor recurrence. A patient with brain abscess on antibiotic treatment, showig increased uptake of $^{201}T1$ in the resolving lesions (index 2.87/1.52) is discussed. In a patient with cerebral infarction, there was no abnormal uptake of $^{201}T1$ in infarcted tissue. When using a threshold index of 1.5, correlation rate between $^{201}T1$ uptake and contrast enhancement of the cerebral lesions on CT/MRI was 73% (8/11). In conclusion, the brain $^{201}T1$ SPECT imaging may be useful for assessment of tumor response to the therapy and to predict low-or high-grade lesions.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.6
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• pp.2523-2527
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• 2014

Background: Serum thyroglobulin detection plays an essential role during the follow-up of thyroid cancer patients treated with total/near total thyroidectomy and radioiodine ablation. The aim of this retrospective study was to evaluate the relationship between stimulated serum thyroglobulin (Tg) level at the time of high dose $^{131}I$ ablation and risk of recurrence, using a three-level classification in patients with differentiated thyroid cancer (DTC) according to the ATA guidelines. Also we investigated the relationship between postoperative stimulated Tg at the time of ablation and DxWBS results at 8-10 months thereafter. Materials and Methods: Patients with radioiodine accumulation were regarded as scan positive (scan+). If there was no relevant pathological radioiodine accumulation or minimal local accumulation in the thyroid bed region, this were regarded as scan negative (scan-) at the time of DxWBS. We classified patients in 3 groups as low, intermediate and high risk group for assessment of risk of recurrence according to the revised ATA guidelines. Also, we divided patients into 3 groups based on the stimulated serum Tg levels at the time of $^{131}I$ ablation therapy. Groups 1-3 consisted of patients who had Tg levels of ${\leq}2ng/ml$, 2-10 ng/ml, and ${\geq}10ng/ml$, respectively. Results: A total of 221 consecutive patients were included. In the high risk group according to the ATA guideline, while 45.5% of demonstrated Scan(+) Tg(+), 27.3% of patients demonstrated Scan(-) Tg(-); in the intermediate group, the figures were 2.3% and 90.0% while in the low risk group, they were 0.6% and 96.4%. In 9 of 11 patients with metastases (81.8%), stimulated serum Tg level at the time of radioiodine ablation therapy was over 10, however in 1 patient (9.1%) it was <2ng/mL and in one patient it was 2-10ng/mL (p=0.005). Aggressive subtypes of DTC were found in 8 of 221 patients and serum Tg levels were ${\leq}2ng/ml$ in 4 of these 8. Conclusions: We conclude that TSH-stimulated serum thyroglobulin level at the time of ablation may not determine risk of recurrence. Therefore, DxWBS should be performed at 8-12 months after ablation therapy.

• The Korean Journal of Nuclear Medicine
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• v.3 no.1
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• pp.73-82
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• 1969

The newly developed diagnostic method with application of $^{113}Sn-^{113m}In$ cow system ($^{113}Sn:\;T\frac{1}{2}$ 118 days, $^{113m}In:\;T\frac{1}{2}$ 1.7 hrs, 390 Kev, Single ${\gamma}$) has the remarkable advantages such as increased diagnostic ability by single large dose administration of $^{113m}In$ with no subsequent radiation hazard and shortened examining time. We reformed the research of following scope with the use of developed $^{113}Sn-^{113m}In$ cow (25 mCi) generator: The sizes of particles produced under various conditions were investigated, and possibility for application to the scannings of various organs such as brain, liver, lung, bone marrow and blood pool etc. were studied. Results: $^{113m}InCl_3$ solution eluted from diluted HCl solution (pH 1.5) passed through $^{113}Sn-^{113m}In$ generator, and there can be produced various sized particles of colloidal indium. And there observed the state of distribution of $^{113m}In$ in each organ which showed many differences according to the particle sizes of colloidal indium. The results are stated as follows: 1. The adjustment of pH is the most important factor in making the desirable particle size of colloidal indium. The colloid for blood pool showed the highest level as 7.1%/gm blood, at pH 1.7, the colloid of pH 3.5 for liver scanning showed the highest level, 88.4%, in the liver, the colloid pH 6 showed the highest level, 3.1%, in the spleen, and the colloid of pH 11.0 showed the highest level, 85.3%/gm, in the lung. 2. The colloid for liver scanning made with NaCl-NaOH system showed the highest liver uptake at pH 7.2, and at either higher or lower pH than 7.2 showed decrease of liver uptake more or less. 3. The activity of $^{113m}In$ eluted through $^{113}Sn-^{113m}In$ generator indicated over 90% in the initial 4 ml, and particularly 88.1%-86.0% in the initial 2 ml. 4. The incubation time, tempertaure and mechanical irritation related to colloid formation and coating of colloid were not the definite condition of influence.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2935-2940
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• 2023

A polystyrene phantom was developed following the guidance of the International Atomic Energy Association (IAEA) for gamma knife (GK) quality assurance. Its performance was assessed by measuring the absorbed dose rate to water and dose distributions. The phantom was made of polystyrene, which has an electron density (1.0156) similar to that of water. The phantom included one outer phantom and four inner phantoms. Two inner phantoms held PTW T31010 and Exradin A16 ion chambers. One inner phantom held a film in the XY plane of the Leksell coordinate system, and another inner phantom held a film in the YZ or ZX planes. The absorbed dose rate to water and beam profiles of the machine-specific reference (msr) field, namely, the 16 mm collimator field of a GK Perfexion^TM or Icon^TM, were measured at seven GK sites. The measured results were compared to those of an IAEA-recommended solid water (SW) phantom. The radius of the polystyrene phantom was determined to be 7.88 cm by converting the electron density of the plastic, considering a water depth of 8 g/cm². The absorbed dose rates to water measured in both phantoms differed from the treatment planning program by less than 1.1%. Before msr correction, the PTW T31010 dose rates (PTW Freiberg GmbH, New York, NY, USA) in the polystyrene phantom were 0.70 (0.29)% higher on average than those in the SW phantom. The Exradin A16 (Standard Imaging, Middleton, WI, USA) dose rates were 0.76 (0.32)% higher in the polystyrene phantom. After msr correction factors were applied, there were no statistically significant differences in the A16 dose rates measured in the two phantoms; however, the T31010 dose rates were 0.72 (0.29)% higher in the polystyrene phantom. When the full widths at half maximum and penumbras of the msr field were compared, no significant differences between the two phantoms were observed, except for the penumbra in the Y-axis. However, the difference in the penumbra was smaller than variations among different sites. A polystyrene phantom developed for gamma knife dosimetry showed dosimetric performance comparable to that of a commercial SW phantom. In addition to its cost effectiveness, the polystyrene phantom removes air space around the detector. Additional simulations of the msr correction factors of the polystyrene phantom should be performed.