• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.557-563
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• 2018

Coincidence summing correction effects are known to be greater as the efficiency of the detector increases and as the distance between the source and the detector increases. A point source($^{60}Co$) was used to vary the distance in the direction of the detector's center axis and in the radial direction to obtain the P/T ratio for Coincidence summing correction calibration. In this study, values for coincidence summing corrected calibration of the values in the central and radial directions were applied to the mixed volume source(450 ml CRM source) to compare the overall peak efficiency change according to P/T with Geant4. In addition, the efficiency obtained from the mapping method is applied to the seaweed, a marine sample, and the compatibility of the P/T ratio with the detector and sample very dose together. The efficiency corrected to 1,836 keV was applied to the energy zone affected by the efficiency of 500 keV and the relative error of the measured and corrected values was well matcched by the 3.2 % peak efficiency correction. As with 450 mL CRM source, the larger the volume, the lower the P/T ratio was by ${\pm}5%$. This is due to the increased scattering of gamma-rays emitted as the source becomes farther away from the detector, and this change in P/T has been confirmed to affect the Coincidence summing corrected peak efficiency.

• Physical Therapy Korea
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• v.10 no.2
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• pp.45-59
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• 2003

The purpose of this study was to assess the effects of ultrasound on adjuvant-induced arthritis in rats. Adjuvant arthritis was induced in 26 female Sprauge-Dawley rats by the subcutaneous injection of a single dose of .1 mL of Complete Freund's Adjuvant (CFA) (1 mg of Mycobacterium Butyricum suspended in .1 $m{\ell}$ paraffin oil) into the right hind paw. After confirming inflammatory edema and arthritis in the paw 2 weeks later, the arthritic rats were divided into 3 groups, i.e., a control group, a pulsed ultrasound group (Group A), and a continuous ultrasound group (Group B) with 8 rats placed in each group. The rats in Group A were treated with pulsed ultrasound at 1 MHz frequency with .5 $W/cm^2$ intensity in 1 : 4 mode for 3 minutes. The rats in Group B were treated with continuous ultrasound at 1 MHz frequency with 2 $W/cm^2$ intensity in the continuous mode for 3 minutes. The ultrasound treatment was done in the left and right ankles for 2 weeks. Clinical, radiographic and histopathologic findings were then evaluated before and after treatment and yielded the following results. 1. No significant difference was present in body weight between the control group and the treated groups. 2. A statistically significant decrease in the edema of the paw was seen in the rats in Group A that was treated with pulsed ultrasound by 26~29 days after the treatment started (p<.05). 3. According to radiological examination, Group A showed the lowest score in arthritis scale which means it showed a tendency to suppress arthritic inflammation of the left and right hind paws. However, no statistically significant difference was present in the score between the control group, Group A and Group B. 4. According to histopathologic findings, the degree of infiltration by inflammatory cells and hypertrophy of the synovium were less in Group A compared with the control group and Group B. The results of the study show that rats that were treated with the pulsed ultrasound effectively suppressed adjuvant arthritis. However, more effort is needed to objectively prove the effectiveness of ultrasound by developing more sensitive testing methods that could quantitatively evaluate the treatment effects of acute rheumatoid arthritis and by trying out different ultrasound treatment methods.

• Journal of the Korean Society of Radiology
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• v.14 no.6
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• pp.763-772
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• 2020

During X-ray examinations in the DR system, the scattered X-rays physically generated by the patient cause image blurring in poor quality. Although X-rays to increase the contrast of images, this increases the patient's exposure dose and is likely to result in grid induced artifacts. Therefore, the purpose of this study is obtain images similar to those of real-grid with non-grid level conditions using a VGR (Virtual Grid Role) algorithm that serves as a virtual grid. Comparing MTF, SNR and CNR of non-grid and VGR algorithm images obtained with 70% exposure conditions of real-grid images showed that the MTF0.5 differed from 0.265 to 0.350 and the MTF0.1 from 0.412 to 0.467 and the SNR, CNR were also different. In addition, comparing MTF, SNR and CNR of VGR algorithm and real-grid images showed that the MTF0.5 differed from 0.350 to 0.367 and the MTF0.1 from 0.467 to 0.483 and the SNR, CNR by little.

• Radiation Oncology Journal
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• v.4 no.1
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• pp.55-62
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• 1986

From Nov. 1983 through Jan. 1986, 43 patients with nonsmall cell lung cancer were treated by radiation therapy at Inje Medical College Paik Hospital. 38 patients were available for the analysis of this study. 33 patients received definite irradiation with curative intent, while 5 patients received postoperative irradiation. Chemotherapy was added in 12 patients before, during and after radio-therapy. 28 patients were squamous cell carcinoma and 10 patients were adenocarcinoma. There were 29 men and 9 women (median age, 50 years; range 34 to 74 years). Stage 1 was 1 patient, Stage 11,7 patient, and Stage 111,30 patients. Among 33 patients who received radiotherapy with curative intent, follow up radiological study revealed complete response in 12 patients $(36\%)$, partial response, in 9 patients $(27\%)$, and minimal response, in 5 patients $(15\%)$, while 7 patients $(21\%)$ were nonresponders. Median survival for all patients was 6.9 months; squamous cell carcinoma, 7.3 months, adenocarcinoma, 5.9 months. Responders survived median 7 months, while nonresponders survived median 1.9 months. Improved complete response rate and survival were shown in high radiation dose group. As prognostic factors, age, initial performance status, sex, histology and tumor location were evaluated.

• Journal of Radiation Protection and Research
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• v.24 no.1
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• pp.39-43
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• 1999

Thermoluminescent (TL) response characteristics of a thin LiF:Mg,Cu,Na,Si Teflon detectors have been studied for use in beta radiation detection. The detectors were fabricated from a mixture of LiF:Mg,Cu,Na,Si phosphor and Teflon powder which was molded into a thin disk form of $50mg/cm^2$ thickness. These detectors were irradiated to beta fields of $^{147}Pm,\;^{204}Tl\;and\;^{90}Sr/^{90}Y$ sources with a covering of Kapton foil ($2mg/cm^2$) and photon irradiation was carried out with a $^{137}Cs$ source at the Korea Atomic Energy Research Institute (KAERI). Batch uniformity was estimated to be 4.7% and the beta dose response presented linear relationship from 0.1 mGy to 100 Gy. The beta energy responses of thin detectors normalized to $^{137}Cs$ were presented as 0.46, 1.09 and 1.06 for $^{147}Pm,\;^{204}Tl\;and\;^{90}Sr/^{90}Y$ beta rays, respectively. The evaluated values for angular responses were $0.93{\pm}0.03\;(^{147}Pm),\;0.94{\pm}0.04\;(^{204}Tl),\;and\;0.92{\pm}0.05\;(^{90}Sr/^{90}Y)$. The results satisfied well a proposed ISO Standard for beta ray dosimeters.

• Journal of Radiation Protection and Research
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• v.45 no.3
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• pp.101-107
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• 2020

Background: An important lesson learned from the Fukushima accident is that the transition to the mid- and long-term phases from the emergency-response phase requires less than a year, which is not very long. It is necessary to know how much radioactive material has been deposited in an urban area to establish mid- and long-term countermeasures after a radioactive accident. Therefore, an urban deposition model that can indicate the site-specific characteristics must be developed. Materials and Methods: In this study, the generalized urban deposition velocity and the subsequent variation in radionuclide contamination were estimated based on the characteristics of the Korean urban environment. Furthermore, the application of the obtained generalized deposition velocity in a hypothetical scenario was investigated. Results and Discussion: The generalized deposition velocities of ¹³⁷Cs, ¹⁰⁶Ru, and ¹³¹I for each residence type were obtained using three-dimensional (3D) modeling. For all residence types, the deposition velocities of ¹³¹I are greater than those of ¹⁰⁶Ru and ¹³⁷Cs. In addition, we calculated the generalized deposition velocities for each residential types. Iodine was the most deposited nuclide during initial deposition. However, the concentration of iodine in urban environment drastically decreases owing to its relatively shorter half-life than ¹⁰⁶Ru and ¹³⁷Cs. Furthermore, the amount of radioactive material deposited in nonresidential areas, especially in parks and schools, is more than that deposited in residential areas. Conclusion: In this study, the generalized urban deposition velocities and the subsequent deposition changes were estimated for the Korean urban environment. The 3D modeling was performed for each type of urban residential area, and the average deposition velocity was obtained and applied to a hypothetical accident. Based on the estimated deposition velocities, the decision-making systems can be improved for responding to radioactive contamination in urban areas. Furthermore, this study can be useful to predict the radiological dose in case of large-scale urban contamination and can support decision-making for long-term measurement after nuclear accident.

• Journal of Korean Neurosurgical Society
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• v.54 no.4
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• pp.329-335
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• 2013

Objective : Brain metastases in primary breast cancer patients are considerable sources of morbidity and mortality. Gamma knife radiosurgery (GKRS) has gained popularity as an up-front therapy in treating such metastases over traditional radiation therapy due to better neurocognitive function preservation. The aim of this study was to clarify the prognostic factors for local tumor control and survival in radiosurgery for brain metastases from primary breast cancer. Methods : From March 2001 to May 2011, 124 women with metastatic brain lesions originating from a primary breast cancer underwent GKRS at a tertiary medical center in Seoul, Korea. All patients had radiosurgery as a primary treatment or salvage therapy. We retrospectively reviewed their clinical outcomes and radiological responses. The end point of this study was the date of patient's death or the last follow-up examination. Results : In total, 106 patients (268 lesions) were available for follow-up imaging. The median follow-up time was 7.5 months. The mean treated tumor volume at the time of GKRS was 6273 $mm^3$ (range, 4.5-27745 mm3) and the median dose delivered to the tumor margin was 22 Gy (range, 20-25 Gy). Local recurrence was assessed in 86 patients (216 lesions) and found to have occurred in 36 patients (83 lesions, 38.6%) with a median time of 6 months (range, 4-16 months). A treated tumor volume >5000 $mm^3$ was significantly correlated with poor local tumor control through a multivariate analysis (hazard risk=7.091, p=0.01). Overall survival was 79.9%, 48.3%, and 15.3% at 6, 12, and 24 months, respectively. The median overall survival was 11 months after GKRS (range, 6 days-113 months). Multivariate analysis showed that the pre-GKRS Karnofsky performance status, leptomeningeal seeding prior to initial GKRS, and multiple metastatic lesions were significant prognostic factors for reduced overall survival (hazard risk=1.94, p=0.001, hazard risk=7.13, p<0.001, and hazard risk=1.46, p=0.046, respectively). Conclusion : GKRS has shown to be an effective and safe treatment modality for treating brain metastases of primary breast cancer. Most metastatic brain lesions initially respond to GKRS, though, many patients have further CNS progression in subsequent periods. Patients with poor Karnofsky performance status and multiple metastatic lesions are at risk of CNS progression and poor survival, and a more frequent and strict surveillance protocol is suggested in such high-risk groups.

• The Journal of Korean Society for Radiation Therapy
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• v.18 no.1
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• pp.29-34
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• 2006

Purpose: The radioprotective effects of white and fermented ginseng on liver damage induced by $^{60}Co\;{\gamma}$-ray were investigated. Materials and Methods: To one group of ICR male mice were given white(150 mg/kg/day for 7 days, orally) and fermented ginseng(150 mg/kg/day for 7 days, orally) before $^{60}Co\;{\gamma}$-ray irradiation. To another group were irradiated by 5 Gy(1.01 Gy/min) dose of $^{60}Co\;{\gamma}$-ray. Contrast group were given with saline(0.1 mL). The levels of reduced(GSH) and oxidized(GSSG) glutathione in liver tissue were measured. Results: In the fermented(150 mg/kg) and white ginseng(150 mg/kg) groups than irradiation group, the GSH levels were significantly increased, but the GSSG levels were significantly decreased. The ratio of GSSG/total GSH was significantly decreased in the fermented(150 mg/kg) and white ginseng(150 mg/kg) groups than irradiation group. Conclusion: In the fermented(150 mg/kg) groups than white ginseng(150 mg/kg) groups the GSH levels were significantly increased. The radioprotective effects of fermented(150 mg/kg) groups than white ginseng(150 mg/kg) groups were increased.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.139-148
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• 2020

The purpose of this study is to propose a method to optimize the performance of Digital Radiography (DR) by analyzing the effect of exposure time change on the stability of radiation output and image quality. The experimental method was used to change the exposure time to 50 msec, 100 msec, 200 msec, and 400 msec so that the Percentage Average Error (PAE), Time-to-Radiation Dose Curve, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR) and theses analysis were performed to evaluate the normal operation of parameters, radiation output and image quality. As a result, all the parameters used in the experiment showed the Percentage Average Error in the normal range, and the shorter the exposure time, the stability of radiation output and image quality decrease. In conclusion, it was found that the performance of Digital Radiography can be optimized when stable radiation output and image quality are applied by applying 100 msec ~ 200 msec exposure time.

• Childhood Kidney Diseases
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• v.18 no.2
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• pp.92-97
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• 2014

Purpose: Bisphosphonates are widely used for the management steroid-induced osteoporosis (SIO) in children. With the increasing use of bisphosphonates, there have been reports of abnormal radiological findings in the growing skeleton. Therefore, their use in pediatric patients remains controversial. The present study was conducted to evaluate the long-term follow-up radiographic features, particularly metaphyseal sclerotic lines, in children who receive pamidronate therapy for nephropathy. Methods: Twenty-four children with nephropathy treated with oral calcium and pamidronate (mean duration, 9 months; dose, 100 mg daily), were evaluated retrospectively. All patients had SIO secondary to chronic glucocorticoid therapy for treating nephropathy. Long bone radiographic imaging was performed before treatment with pamidronate, and at follow-up, several years later. Physeal growth rates were estimated by measuring the distance that the sclerotic lines moved on the radiographs during the corresponding time intervals. Results: The mean follow-up period was 138 months. Long bone radiographs showed well-defined sclerotic lines at the metaphyseal ends, progressively moving from the physeal plate to the diaphysis, in all patients. The mean rate of movement of the sclerotic line was 6.21 mm per year. In 12 patients, the lines disappeared. The mean rate of growth in height was 7.33 cm per year. Conclusions: Results of long-term follow-up suggest that the metaphyseal sclerotic lines associated with pamidronate treatment tend to disappear without affecting overall skeletal growth. Bisphosphonate treatment for SIO in children with nephropathy seems to be safe, although further studies in larger number of patients are needed.