• Radiation Oncology Journal
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• v.16 no.3
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• pp.325-335
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• 1998

Purpose : Since the mid cranial fossa is composed of various thickness of bone, the tissue inhomogeneity caused by bone would produce dose attenuation in cobalt-60 gamma knife irradiation. The correction factor for bone attenuation of cobalt-60 which is used for gamma knife source is -3.5$\%$. More importantly, nearly all the radiosurgery treatment planning systems assume a treatment volume of unit density: any perturbation due to tissue inhomogeneity is neglected, This study was performed to confirm the bone attenuation in mid cranial fossa using gamma knife. Materials and Methods : Computed tomography was performed after Leksell stereotactic frame had been liked to the Alderson Rando Phantom (human phantom) skull area. Kodak X-omat V film was inserted into two sites of pituitary adenoma point and acoustic neurinoma point, and irradiated by gamma knife with 14mm and 18mm collimator. An automatic scanning densitometer with a 1mm aperture is used to measure the dose profile along the x and y axis. Results : Isodose curve constriction in mid cranial fossa is observed with various ranges. Pituitary tumor point is greater than acoustic neurinoma point (0.2-3.0 mm vs 0.1-1.3 mm) and generally 14 mm collimator is greater than 18mm collimator (0.4-3.0 mm vs. 0.2-2.2 mm) Even though the isodose constriction is found, constriction of 50$\%$ isodose curve which is used for treatment reference line does not exceed 1 mm. This range is too small to influence the treatment planning and treatment results. Conclusion : Radiosurgery planning system of gamma knife does not show significant error to be corrected without consideration of bone attenuation.

• Journal of Korean Academy of Nursing
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• v.28 no.4
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• pp.893-907
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• 1998

The purpose of this study was to determine the effect of regular exercise during dexamethasone injection on the body weight, weight of hindlimb muslces, myofibrillar protein content and glutamine synthetase activity. 180-200g female Wistar rats were divided into four groups : control, exercise, dexamethasone injection (dexa), and exercise during dexamethasone injection(D+E) group. The dexa group received daily subcutaneous injection of dexamethasone at a dose of 4mg/kg body weight for 7 days. The exercise group ran on a treadmill for 60min/day(20minutes every 4 hours) at 10m/min and a 10$^{\circ}$grade. The control group received daily subcutaneous injection of normal saline at a dose of 4mg/kg body weight for 7 days. The D+E group ran on a treadmill for 60min/day(20minutes every 4 hours) at 10m/min and a 10$^{\circ}$ grade during dexamethasone injection. Body weight of the control group increased significantly from days of experiment, that of the dexa group decreased significantly from day 4 of the experiment resulting in a 82.4% decrease compared to the first day of the experiment. Body weight of the D+E group decreased significantly from day 5 of experiment resulting in a 81.77% decrease comprared to the first day of the experiment. Body weights, muscle weight and myofibrillar protein content of the plantaris and gastrocnemius decreased significantly and muscle weight of the soleus tended to decrease with dexamethasone injection. Glutamine synthetase activity of the hindlimb muscles increased significantly with the dexamethasone injection. The relative weight of the soleus was comparable to the control group and that of plantaris decreased significantly and that of gastrocnemius tended to decrease compared to that of the control in the dexa group. Body weight and muscle weight of the plantaris and gastrocnemius of the excrcise group were comparable to the control group, and the muscle weight of soleus showed a tendencey to increase. The relative weight of the soleus increased significantly and that of the plantaris and gastrocnemius were comparable to the control in the exercise group. Myofibrillar protein content of the soleus and plantaris increased significantly and there was no change of GS activity of the hindlimb muscles compared to the control in the exercise group. Body weight of the D+E group was comparable to the dexa group, muscle weight of the plantaris increased significantly and that of the soleus and gastrocnemius showed a tendency to increase. The relative weight of the hindlimb muscles increased significantly. Myofibrillar protein content of the soleus and plantaris increased significantly and that of the gastrocnemius tended to increase compared to the dexa group. Body weight and muscle weight of the plantaris and gastrocnemius of the D+E group did not recover to that of the control group. Muscle weight of the soleus recovered to that of the control group. The relative weight and of myofibrillar protein content of the hindlimb muscles recovered to that of the control group. From these results, it is suggested that regular exercise during dexamethasone injection might attenuate the muscle atrophy of the hindlimb muscles.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.1
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• pp.50-53
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• 2017

Purpose The change in uniformity due to the decreasement in dose should be known. $^{57}Co$ sealed sources are easy to manage and use as QC sources replacing $^{99m}Tc$. Overlapping sealed sources are expected to show variations in dose due to attenuation between sealed sources. Materials and Methods A total of three experiments were conducted. The first experiment is to observe the change in the degree of senescence of the $^{57}Co$ sealed source. The second experiment is to compare the single source and overlaped source at similar doses. In the third experiment, the sources of different doses were compared on each other to determine the changes due to the attenuation between the overlapping sources. Results The results of the first experiment did not exceed the acceptable range. but each crew showed a difference. There was no statistically significant difference in the measurement of uniformity on second and third experiment Conclusion It is believed that a $^{57}Co$ sealed source can be used as a superimposed source. It is not only economical but also convenient to use. daily uniformity measurements will help reduce scan time and speed up the testing process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.564-567
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• 2012

Optical fibers are going to be used for telecommunication, image fibers, sensors under irradiation in nuclear power plants and various irradiation facilities. Especially, Temperature detection sensors using Raman light scattering, temperature or strain sensors using fiber gratings, magnet-optical sensors using photo-magnetic effect, are already commercialized. However, When fibers are exposed to ionizing radiation, color centers are formed in fibers which reduces their light transmission, and it is limited in applying under radiation environments. In this study, $Co^{60}$ gamma-ray induced optical attenuation on Ge-doped single mode(SM) fiber has been measured. Gamma-ray is irradiated for 4hours at the dose rate of 0.5kGy/hr, 2kGy/hr, 8kGy/hr. Consequently, gamma-ray induced loss based on radiation effects in Ge-doped SM fiber occur precisely. Furthermore, dose rate effect that the higher dose rate in the same total dose, the more increase loss of optical fiber and annealing effect that the higher the loss after irradiation, the more increase the recovery rate of the loss are observed in the fiber. This results plan to make use of bases in the study of the radiation-hardened optical fiber.

• The Korean Journal of Nuclear Medicine
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• v.33 no.4
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• pp.422-429
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• 1999

Purpose: The measurement of radiation absorbed dose is useful to predict the response after I-131 labeled metaiodobenzylguanidine (MIBG) therapy and determine therapy dose in patients with unresectable or malignant pheochromocytoma. We estimated the absorbed dose in tumor tissue after high dose I-131 MIBG in a patient with pheochromocytoma using a gamma camera and Medical Internal Radiation Dose (MIRD) formula. Materials and Methods: A 64-year old female patient with pheochromocytoma who had multiple metastases of mediastinum, right kidney and periaortic lymph nodes, received 74 GBq (200 mCi) of I-131 MIBG. We obtained anterior and posterior images at 0.5, 16, 24, 64 and 145 hours after treatment. Two standard sources of 37 and 74 MBq of I-131 were imaged simultaneously. Cummulated I-131 MIBG uptake in tumor tissue was calculated after the correction of background activity, attenuation, system sensitivity and count loss at a high count rate. Results: The calculated absorbed radiation dose was 32-63 Gy/ 74 GBq, which was lower than the known dose for tumor remission (150-200 Gy). follow-up studies at 1 month showed minimally reduced tumor size on computed tomography, and mildly reduced I-131 MIBG uptake. Conclusion: We estimated radiation absorbed dose after therapeutic I-131 MIBG using a gamma camera and MIRD formula, which can be peformed in a clinical nuclear medicine laboratory. Our results suggest that the measurement of radiation absorbed dose in I-131 MIBG therapy is feasible as a routine clinical practice that can guide further treatment plan. The accuracy of dose measurement and correlation with clinical outcome should be evaluated further.

• The Journal of the Korea Contents Association
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• v.13 no.8
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• pp.301-307
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• 2013

In the present study, space doses generated during X-ray radiography of hand, head, and abdomen, etc. were examined and whether the intensity of space doses of scattering rays is attenuated by the "inverse square law of distance" was figured out. First, the space doses of X-ray with small amounts of generated scattering rays such as hand radiography were mostly attenuated by the "inverse square law of distance" and were not detected at all at a distance of 2m. Second, the space doses of X-ray with large amounts of generated scattering rays such as head or abdomen radiography attenuated in higher rates than the rates under the "inverse square law of distance" at distances ranging from 30cm to 1m from the center of the irradiation field and were attenuated by the "inverse square law of distance" at distances ranging from 1m to 2m. Therefore, in X-ray rooms, the subject should be at least 2m away from the center of the irradiation field in the case of hand radiography and X-ray exposure prevention actions using protective devices are required in the entire spaces of the X-ray rooms in the case of head or abdomen radiography.

• Nuclear Engineering and Technology
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• v.6 no.4
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• pp.239-247
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• 1974

A human phantom of polyethylene has been designed and sculptured for studying the effective radiation safety control. The phantom has the approximate size of the Korean adult and was sliced into thirty-five transverse slabs, 2.5 cm thick, The relative dose at the specified position was determined from the exposure that a TLD badge worn on the surface of the phantom body received from external ${\gamma}$-ray. The variation of the exposure as a function of depth in the phantom was measured for uncollimated ${\gamma}$-ray using TLD rods, and also isodose curves were obtained for the anatomical cross-section of the critical organs of the body. To simulate radiation exposure condition in the nuclear facility, measurements were made for given angles of incident ${\gamma}$-ray. The front to back attenuation factor for human phantom of thickness 20 cm was 0.439 for Cs$^{137}$ ${\gamma}$-ray which is in reasonable agreement with the published data.

• Korean Journal of Plant Resources
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• v.19 no.6
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• pp.649-654
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• 2006

The objective of present study was to investigate the anti oxidative and hepatoprotective effects of tomato extracts. Total antioxidant capacity and total antioxidant response were 5.5 and $19.8{\mu}g$ Trolox equivalent per mg of tomato extract, respectively. DPPH radical scavenging activity of tomato extracts ($10mg\;ml^{-1}$) was 70% as compared to 100% by pyrogallol solution as a reference. The effect of the tomato extracts on lipid peroxidation was examined using rat liver mitochondria induced by iron/ascorbate. Tomato extracts at the concentration of $0.5mg\;ml^{-1}$ significantly decreased TBARS concentration. Tomato extracts prevented lipid peroxidation in a dose-dependent manner. The effect of the tomato extracts on reactive oxygen species (ROS) generation was examined using cell-free system induced by $H_2O_2/FeSO_4$. Addition of $1mg\;ml^{-1}$ of tomato extracts significantly reduced dichlorofluorescein (DCF) fluorescence. Tomato extracts caused concentration-dependent attenuation of the increase in DCF fluorescence, indicating that tomato extracts significantly prevented ROS generation in vitro. The effect of tomato extracts on cell viability and proliferation was examined using hepatocyte culture. Primary cultures of rat hepatocytes were incubated with 1mM tert-butyl hydroperoxide (t-BHP) for 90 min in the presence or absence of tomato extracts. MTT values by addition of tomato extracts at the concentration of 2, 10, and $20mg\;ml^{-1}$ in the presence of t-BHP were 13, 33 and 48%, respectively, compared to 100% as control. Tomato extracts increased cell viability in a dose-dependent manner. These results demonstrate that tomato extracts suppressed lipid peroxidation and t-BHP-induced hepatotoxicity and scavenged ROS generation. Thus antioxidant and hepatoprotective effects of tomato extracts seem to be due to, at least in part, the prevention from free radicals-induced oxidation, followed by inhibition of lipid peroxidation.

• The Journal of Korean Society for Radiation Therapy
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• v.10 no.1
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• pp.69-77
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• 1998

When a high energy photon beam is used to treat lesions located in the upper respiratory air passages or in maxillary sinus, the beams often must traverse an air cavity before it reaches the lesion. Because of this traversal of air, it is not clear that the surface layers of the lesion forming the air-tumor tissue interface will be in a state of near electronic equilibrium; if they are not, underdosing of these layers could result. Although dose corrections at large distances beyond an air cavity are accountable by attenuation differences, perturbations at air-tissue interfaces are complex to measure or calculate. This problem has been investigated for 4MV and 10MV X-ray beams which are becoming widely available for radiotherapy with linear accelerator. Markus chamber was used for measurement with variouse air cavity geometries in X-ray beams. Underdosing effects occur at both the distal and proximal air cavity interface. The magnitude depended on geometry, energy, field sizes and distance from the air-tissue interfaces. As the cavity thickness increased, the central axis dose at the distal interface decreased. Increasing field size remedied the underdosing, as did the introduction of lateral walls. Fellowing a $20{\times}2{\times}2\;cm^3$\;air\;cavity,\;4{\times}4\;cm\;field\;there\;was\;an\;11.5\%\;and\;13\%\;underdose\;at\;the\;distal\;interface,\;while\;a\;20{\times}20{\times}2\;cm^3\;air\;cavity\;yielded\;a\;24\%\;and\;29\%$ loss for the 4MV and 10MV beams, respectively. The losses were slightly larger for the 10MV beams. The measurements reported here can be used to guide the development of new calculation models under non-equilibrium conditions. This situation is of clinical concern when lesions such as larynx and maxillary carcinoma beyond air cavities are irradiated.

• Journal of Radiation Protection and Research
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• v.4 no.1
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• pp.21-28
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• 1979

A calculation is presented of air-scattered gamma rays using the modified single-scattering approximation. The air-scattered tissue dose rates are calculated for a general purpose taking into account (a) the buildup and exponential attenuation, (b) the energy spectrum at the position of question and (c) the geometrical scattering volume in three dimensions. These calculations have been further modified to render them applicable to a typical field irradiation facility which is surrounded by a shield wall and in which the source is fitted with a beam collimating device. The results of the calculation include the energy spectra, angular distribution and tissue does rates at source-receiver separation distances of from 35m to 300m. The comparison shows that the present method developed may be generally adequate for the gamma-ray air-scattering problems in field irradiation facilities if energy and angular distribution at the shield are unimportant.