• Journal of Radiation Protection and Research
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• v.23 no.3
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• pp.175-184
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• 1998

In order to calculate dose rates from steam generators to be replaced from Kori unit 1 in 1998, radionuclide inventories inside steam generator were evaluated from smear test results and measured dose rates from S/G tubes withdrawn for the metallographical examination of damaged tubes. Based on the inventories, contact dose rates and dose rates at 1 m from the surface of a steam generator were calculated using the QAD-CG computer code. Contact dose rates ranged from 11.5 mR/hr at the bottom of channel head to 37.7 mR/hr at the middle of shell barrel, and showed no significant difference with dose rates at 1 m from the surface of steam generator. Shielding effects of lead and carbon steel were compared to provide basic shielding data. Lead shield showed excellent shielding effects. Dose rate at 1 m from the middle of S/G shell barrel decreased from 38.6 mR/hr to 15.5 mR/hr with the lead shield of 2 mm thickness. However, carbon steel showed a poor shielding effect even with the thickness of 2.0 cm. This can be explained with the great differences in the attenuation effect and buildup factor between lead and carbon steel for low energy photons.

• Radiation Oncology Journal
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• v.24 no.4
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• pp.211-216
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• 2006

$\underline{Purpose}$: An analysis of the infrastructure for radiotherapy in Korea was performed to establish a baseline plan in 2006 for future development. $\underline{Materials\;and\;Methods}$: The data were obtained from 61 radiotherapy centers. The survey covered the number of radiotherapy centers, major equipment and personnel. Centers were classified into technical level groups according to the IAEA criteria. $\underline{Results}$: 28,789 new patients were treated with radiation therapy in 2004. There were 104 megavoltage devices in 61 institutions, which included 96 linear accelerators, two Cobalt 60 units, three Tomotherapy units, two Cyberknife units and one proton accelerator in 2006. Thirty-five high dose rate remote after-loading systems and 20 CT-simulators were surveyed. Personnel included 132 radiation oncologists, 50 radiation oncology residents, 64 medical physicists, 130 nurses and 369 radiation therapy technologists. All of the facilities employed treatment-planning computers and simulators, among these thirty-two percent (20 facilities) used a CT-simulator. Sixty-six percent (40 facilities) used a PET/CT scanner, and 35% (22 facilities) had the capacity to implement intensity modulated radiation therapy. Twenty-five facilities (41%) were included in technical level 3 group (having one of intensity modulated radiotherapy, stereotactic radiotherapy or intra-operative radiotherapy system). $\underline{Conclusion}$: Radiation oncology in Korea evolved greatly in both quality and quantity recently and demand for radiotherapy in Korea is increasing steadily. The information in this analysis represents important data to develop the future planning of equipment and human resources.

• Journal of the Korean Society of Radiology
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• v.10 no.7
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• pp.495-502
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• 2016

In this study, we analyzed the effects of radiation exposure, as compared to the hematological parameters change of medical radiation workers and the public. The mean value of all hematological parameters were in the normal range. Eosin mean value of the radiation workers($2.52{\pm}1.79%$) showed that a significantly lower than the control group($2.92{\pm}1.39%$). In the comparison of the results depending on the occupation period, it showed high value that the mean of the radiation workers group WBC, platelet, Lymph, Mono, Baso. Over 20 years of radiation workers WBC, Mono showed low values and less than 10 years of radiation workers mean value of Baso showed low values, there was no statistical significance. In the comparison of the results depending on the 4 years cumulative radiation dose, Over 5.0 mSv of Radiation works RBC($4.61{\pm}0.53$ vs $4.91{\pm}0.38$), Hct($41.51{\pm}4.07$ vs $43.97{\pm}3.40$), Eosin($1.74{\pm}1.14$ vs $2.92{\pm}1.39$) showed low value, it was statistical significance. 0.5~1.0 mSv radiation exposure workers Hb ($13.93{\pm}1.75$) showed a significantly lower value than that of the control group ($14.90{\pm}1.29$).

• The Korean Journal of Nuclear Medicine
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• v.37 no.2
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• pp.110-119
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• 2003

Purpose: Radioiodine (I-131) therapy is an effective modality to reduce both recurrence and mortality rates in differentiated thyroid cancer. Whether higher doses shows higher therapeutic responses was still debatable. The purpose of this study was to validate curve-fitting (CF) method measuring maximum permissible dose (MPD) by a biological dosimetry using metaphase analysis of peripheral blood lymphocytes. Materials and Methods: Therapeutic effects of MPD was evaluated in 58 patients (49 females and 9 males, mean age $50{\pm}11$ years) of papillary thyroid cancer. Among them 43 patients were treated with ${\Leq}7.4GBq$, while 15 patients with ${\geq}9.25GBq$. The former was defined as low-dose group, and the latter high-dose group. Therapeutic response was defined as complete response when complete disappearance of lesions on follow-up I-131 scan and undetectable serum thyroglobulin levels were found. Statistical comparison between groups were done using chi-square test. P value less than 0.05 was regarded as statistically significant. Results: MPD measured by CF method using tracer and therapeutic doses were $13.3{\pm}1.9\;and\;13.8{\pm}2.1GBq$, respectively (p=0.20). They showed a significant correlation (r=0.8, p<0.0001). Exposed doses to blood measured by CF and biological methods were $1.54{\pm}0.03\;and\;1.78{\pm}0.03Gy$ (p=0.01). They also showed a significant correlation (r=0.86, p=0.01). High-dose group showed a significantly higher rate of complete response (12/15, 80%) as compared to the low-dose group (22/43, 51.2%) (p=0.05). While occurrence of side effects was not different between two groups (40% vs. 30.2%, p=0.46). Conclusion: Measurement of MPD using CF method is reliable, and the high-dose I-131 therapy using MPD gains significantly higher therapeutic effects as compared with low-dose therapy.

• Radiation Oncology Journal
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• v.25 no.4
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• pp.278-282
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• 2007

Purpose: Diffuse pigmented villonodular synovitis (PVNS) is an uncommon aggressive synovial proliferative disorder of unknown etiology affecting the joint linings. Though a histologically benign inflammatory process, because of its aggressive growth with bone destruction or recurrence, it is frequently suggested to occur as a low malignant neoplasm. Optimal treatment is surgery, but the local recurrence rate after radical synovectomy for diffuse PVNS is relatively high due to the infiltrative growth pattern. External beam radiotherapy with moderate doses or intra-articular instillation of radioactive isotopes may improve the likelihood of local control and long-term function in patients with incompletely resected or recurrent diffuse PVNS. I report one case of diffuse PVNS of the right knee joint treated with arthroscopic synovectomy and external beam radiotherapy is presented.

• Radiation Oncology Journal
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• v.26 no.2
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• pp.96-103
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• 2008

Purpose: To conduct a nationwide academic hospital patterns of the practice status and principles of radiotherapy for prostate cancer. The survey will help develop the framework of a database of Korean in Patterns of Case Study. Materials and Methods: A questionnaire about radiation treatment status and principles was sent to radiation oncologists in charge of prostate cancer treatment at thirteen academic hospitals in Korea. The data was analyzed to find treatment principles among the radiation oncologists when treating prostate cancer. Results: The number of patients with prostate cancer and treated with radiation ranged from 60 to 150 per academic hospital in Seoul City and 10 to 15 outside of Seoul City in 2006. The primary diagnostic methods of prostate cancer included the ultrasound guided biopsy on 6 to 12 prostate sites(mean=9), followed by magnetic resonance imaging and a whole body bone scan. Internal and external immobilizations were used in 61.5% and 76.9%, respectively, with diverse radiation targets. Whole pelvis radiation therapy(dose ranging from 45.0 to 50.4 Gy) was performed in 76.9%, followed by the irradiation of seminal vesicles($54.0{\sim}73.8$ Gy) in 92.3%. The definitive radiotherapy doses were increased as a function of risk group, but the range of radiation doses was wide(60.0 to 78.5 Gy). Intensity modulated radiation therapy using doses greater than 70 Gy, were performed in 53.8% of academic hospitals. In addition, the simultaneous intra-factional boost(SIB) technique was used in three hospitals; however, the target volume and radiation dose were diverse. Radiation therapy to biochemical recurrence after a radical prostatectomy was performed in 84.6%; however, the radiation dose was variable and the radiation field ranged from whole pelvis to prostate bed. Conclusion: The results of this study suggest that a nationwide Korean Patterns of Care Study is necessary for the recommendation of radiation therapy guidelines of prostate cancer.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.37-43
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• 2012

Radioactive waste transport package was developed to transport eight drums of low and intermediate level waste(LILW) in accordance with the IAEA and domestic related regulations. The package is classified with industrial package IP-2. IP-2 package is required to undergo a free drop test and a stacking test. After free drop and stacking tests, it should prevent the loss or dispersal of radioactive contents, and loss of shielding integrity which would result in more than 20 % increase in the radiation level at any external surface of the package. The objective of this study is to establish the safety test method and procedure for stacking test and to prove the structural integrities of the IP-2 package. Stacking test and analysis were performed with a compressive load equal to five times the weight of the package for a period of 24 hours using a full scale model. Strains and displacements were measured at the corner fitting of the package during the stacking test. The measured strains and displacements were compared with the analysis results, and there were good agreements. It is very difficult to measure the deflection at the container base, so the maximum deflection of the container base was calculated by the analysis method. The maximum displacement at the corner fitting and deflection at the container base were less than their allowable values. Dimensions of the test model, thickness of shielding material and bolt torque were measured before and after the stacking test. Throughout the stacking test, it was found that there were no loss or dispersal of radioactive contents and no loss of shielding integrity. Thus, the package was shown to comply with the requirements to maintain structural integrity under the stacking condition.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.1
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• pp.57-65
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• 2019

Purpose: The purpose is to clarify the effect of additional scattering ratio on the edge of the block according to the increasing block thickness with low melting point lead alloy and pure lead in electron beam therapy. Methods and materials: $10{\times}10cm^2$ Shielding blocks made of low melting point lead alloy and pure lead were fabricated to shield mold frame half of applicator. Block thickness was 3, 5, 10, 15, 20 (mm) for each material. The common irradiation conditions were set at 6 MeV energy, 300 MU / Min dose rate, gantry angle of $0^{\circ}$, and dose of 100 MU. The relative scattering ratio with increasing block thickness was measured with a parallel plate type ion chamber(Exradin P11) and phantom(RW3) by varying the position of the shielding block(cone and on the phantom), the position of the measuring point(surface ans depth of $D_{max}$), and the block material(lead alloy and pure lead). Results : When (depth of measurement / block position / block material) was (surface / applicator / pure lead), the relative value(scattering ratio) was 15.33 nC(+0.33 %), 15.28 nC(0 %), 15.08 nC(-1.31 %), 15.05 nC(-1.51 %), 15.07 nC(-1.37 %) as the block thickness increased in order of 3, 5, 10, 15, 20 (mm) respectively. When it was (surface / applicator / alloy lead), the relative value(scattering ratio) was 15.19 nC(-0.59 %), 15.25 nC(-0.20 %), 15.15 nC(-0.85 %), 14.96 nC(-2.09 %), 15.15 nC(-0.85 %) respectively. When it was (surface / phantom / pure lead), the relative value(scattering ratio) was 15.62 nC(+2.23 %), 15.59 nC(+2.03 %), 15.53 nC(+1.67 %), 15.48 nC(+1.31 %), 15.34 nC(+0.39 %) respectively. When it was (surface / phantom / alloy lead), the relative value(scattering ratio) was 15.56 nC(+1.83 %), 15.55 nC(+1.77 %), 15.51 nC(+1.51 %), 15.42 nC(+0.92 %), 15.39 nC(+0.72 %) respectively. When it was (depth of $D_{max}$ / applicator / pure lead), the relative value(scattering ratio) was 16.70 nC(-10.87 %), 16.84 nC(-10.12 %), 16.72 nC(-10.78 %), 16.88 nC(-9.93 %), 16.90 nC(-9.82 %) respectively. When it was (depth of $D_{max}$ / applicator / alloy lead), the relative value(scattering ratio) was 16.83 nC(-10.19 %), 17.12 nC(-8.64 %), 16.89 nC(-9.87 %), 16.77 nC(-10.51 %), 16.52 nC(-11.85 %) respectively. When it was (depth of $D_{max}$ / phantom / pure lead), the relative value(scattering ratio) was 17.41 nC(-7.10 %), 17.45 nC(-6.88 %), 17.34 nC(-7.47 %), 17.42 nC(-7.04 %), 17.25 nC(-7.95 %) respectively. When it was (depth of $D_{max}$ / phantom / alloy lead), the relative value(scattering ratio) was 17.45 nC(-6.88 %), 17.44 nC(-6.94 %), 17.47 nC(-6.78 %), 17.43 nC(-6.99 %), 17.35 nC(-7.42 %) respectively. Conclusions: When performing electron therapy using a shielding block, the block position should be inserted applicator rather than the patient's body surface. The block thickness should be made to the minimum appropriate shielding thickness of each corresponding using energy. Also it is useful that the treatment should be performed considering the influence of scattering dose varying with distance from the edge of block.

• Clinical and Experimental Pediatrics
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• v.46 no.6
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• pp.554-560
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• 2003

Purpose : To investigate the teratogenic effect of gamma-ray on the heart of chick embryo. Methods : 50 rad, 100 rad, 150 rad, 200 rad, 250 rad, and 300 rad of gamma-ray were used to irradiate three days old chick embryos. The control group was not irradiated. After three weeks, the embryos were sacrificed and examined for cardiovascular malformation. Results : The survival rate of the gamma-ray irradiated group was significantly lower than that of the control group(33.3-63.3% vs 76.4%, P=0.001). The cardiac malformation rate of the experimental group was 11.0%. In the control group, no congenital cardiac malformations were observed. The experimental groups had a significantly higher malformation rate(P=0.001). The types of malformation were ventricular septal defect, tricuspid atresia, Ebstein anomaly and aortic arch anomaly. In the gamma-ray irradiated group, the cardiac malformations were : 14 small ventricular septal defects (VSDs), five large VSDs, two tricuspid atresias, and one Ebstein anomaly. The higher the dose of radiation applied, the higher the incidence of cardiac malformation was noted. Conclusion : Gamma-ray irradiation of 3 days old chick embryos increased the rate of death and the rate of cardiac malformation significantly.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.214-227
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• 2013

Computed tomographic scan as a screening procedures in asymptomatic individuals has seen a steady increase with the introduction of multiple-raw detector CT scanners. This report provides a brief review of the current controversy surrounding CT cancer screening, with a focus on the radiation induced cancer risks and clinical efficacy. 1. A large study of patients at high risk of lung cancer(the National Lung Screening Trial[NLST]) showed that CT screening reduced cancer deaths by 20%(1.33% in those screened compared with 1.67% in those not screened). The rate of positive screening tests was 24.2% and 96.4% of the positive screening results in the low-dose CT group were false-positive. Radiation induced lung cancer risk was estimated the most important in screening population because ERR of radiation induced lung cancer does not show the decrease with increasing age and synergistic connection between smoking and radiation risk. Therefore, the radiation risk may be on the same order of magnitude as the benefit observed in the NLST. Optimal screening strategy remain uncertain, CT lung cancer screening is not yet ready for implementation. 2. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but significantly less sensitive and specific for smaller lesions and disadvantageous for subsequent therapeutic optical colonoscopy if polyps are detected. The average effective dose from CT colonography was estimated 8-10 $mS{\nu}$, which could be a significant dose if administered routinely within the population over many years. CT colonography should a) achieve at least 90% sensitivity and specificity in the size category from 6 and 10 mm, b) offer non-cathartic bowl preparation and c) be optimized and standardized CT parameters if it is to be used for mass screening. 3. There is little evidence that demonstrates, for whole-body scanning, the benefit outweighs the detriment. This test found large portion of patient(86~90.8%) had at least one abnormal finding, whereas only 2% were estimated to have clinically significant disease. Annual scans from ages 45 to 75 years would accrue an estimated lifetime cancer mortality risk of 1.9%. There is no group within the medical community that recommends whole-body CT. No good studies indicate the accuracy of screening CT, at this time. The benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established. These areas need further research. Therefore wild screening should be avoided.