• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.283-292
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• 2024

Radiation side effects and complications on the ocular adnexa during electron beam therapy for orbital lymphoma can increase the incidence of posterior subcapsular cataracts. This study simulated a medical linear accelerator and a mathematical model of the eye using monte carlo simulations to evaluate the dose to the ocular adnexa and compare the shielding effectiveness on different parts of the ocular adnexa based on lens shield thickness. The dose assessment results of the ocular adnexa showed that the lens's sensitive area had the highest absorbed dose distribution when no shield was used, followed by the lens's non-sensitive area, the anterior chamber, vitreous humor, cornea, and eyelid in descending order. With the use of a shield, a 2 mm thick shield demonstrated a dose reduction effect of over 90% in the lens's sensitive area, over 83% in the non-sensitive area and anterior chamber, and a dose reduction effect of 30 to 62% in the vitreous body, cornea, and eyelid. For dose reduction in the lens's sensitive area during electron beam therapy for orbital lymphoma, it is necessary to use a shield of at least 2 mm thickness. Additionally, shielding strategies considering the thickness and area of the shield for other ocular adnexa besides the lens are required.

• Progress in Medical Physics
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• v.22 no.4
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• pp.216-223
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• 2011

Recently PTW developed a MicroLion liquid ionization chamber which is water_equivalent and has a small sensitive volume of $0.002cm^3$. The aim of this work is to investigate such dosimetric characteristics as dose linearity, dose rate dependency, spatial resolution, and output factors of the chamber for the external radiotherapy photon beam. The results were compared to those of Semiflex chamber, Pinpoint chamber and Diode chamber with the sensitive volumes of $0.125cm^3$, $0.03cm^3$ and $0.0025cm^3$, respectively and evaluated to be suitable for small fields. This study was performed in the 6MV photon energy from a Varian 2300 C/D linac accelerator and the MP3 water phantom (PTW, Freiburg) was used. Penumbras in the varios field sizes ranged from $0.5{\times}0.5cm^2$ to $10{\times}10cm^2$ were used to evaluate the spatial resolution. Output factors were measured in the field sizes of $0.5{\times}0.5$ to $40{\times}40cm^2$. Readings of the chamber was linearly proportional to dose. Dose rate dependency was measured from 100 MU/min to 600 MU/min, showed a maximum difference of 5.0%, and outputs decreased with dose rates. The spatial resolutions determined with comparing profiles for the field sizes of $0.5{\times}0.5cm^2$ to $10{\times}10cm^2$ agreed between every detector except the Semiflex chamber to within 2%. Outputs of detectors were compared to that of Semiflex chamber and showed good agreements within 2% for every chamber. This study shows that MicroLion chamber characterized by a high signal-to-noise ratio and water equivalence could be suitable for the small field dosimetry.

• Journal of the Korean Society of Radiology
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• v.5 no.5
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• pp.223-229
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• 2011

When negative electron in x-ray tube is accelerated in to a high speed and then the currency of the electron is blocked by the target, x-ray happens by the conversion of the energy. The real area where the fast accelerated electron collides to a target area is called actual focal spot. When the string focused size is observed at the central ray side, where the direction x-ray comes out, the size seems to be reduced. This focus is called effective focal spot. According to radiation angle of x-rays tube, the degree of the negative pole side presents higher value than inclination, the amount of exposed radiation that patient receives differs by the angle of positive pole, which means effective focal spot is the variable. This paper presents the correlation between size of effective focal spot and amount of exposed radiation to the patient by it, and effective research for homogenized dose dispersion by the size of effective focal spot. In conclusion, following the focal size, effective range which was -8cm ~ 0 cm on average, was found and average dose rate was 0.019 R/min. Through this range, for patients with small radiation exposure, image with good density and resolution in aspect of diagnosing will be able to be obtained.

• Journal of Korean Society of Forest Science
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• v.25 no.1
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• pp.80-84
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• 1975

The seeds, scions and plants of chestnut tree (Castanea. crenata) and Chinese chestnut tree (C. bungeana) were irradiated by gamma ray in order to know their biological effects on germination, plant growth and mutation at several accumulative doses and dose rates. The results of this study could be summarized as follows: 1. In general, the radio-sensitivity of scions was more sensitive to irradiation, showing 50% reduction dose of the control for grafting percentage at 3.1 kR as compared with 4.6 kR for the above reduction dose in germination rates of seeds. 2. The seeds treated by 5 kR dose resulted in some albino mutants at a rate of 0.84%. There was a general tendency that the seedling height reduced significantly as the irradiation dose increased. 3. The scions treated by an acute irradiation showed their 50% reduction dose in grafting at 3.2 kR for Chinese chestnut and at 3.1 kR for chestnut, respectively, while their irradiation doses increased three times, having 10.2 kR for the 50% reduction dose in the case of semi-acute irradiation. 4. When Chinese chestnut trees were irradiated during their dormant period with a total dose of 7.5 kR to 4.9 kR at a dose rate of 150 R to 98 R per day, there were induced giant leaf bud-sports at a frequency of 16.6%. The averag leaf area of the giant leaf bud-sports were measured at 96.36 square centimeters, while the area of normal leaf was only 26.28 square centimeters.

• Journal of Radiation Protection and Research
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• v.37 no.4
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• pp.208-212
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• 2012

In previous studies, ovarian follicle in rat has been used a higher radiation dose than that for cancer radiotherapy in clinical practice. The aim of this study was to evaluate the effect of radiation dose used for cancer radiotherapy on ovarian follicle atresia in rat. Mice of 4-week-old female were whole body irradiated with 2 cGy or 2 Gy (Mevatron 67, Siemens, Germany) and sacrificed by cervical dislocation. Ovaries were collected at 24 hours after irradiation to observe the degree of follicular atresia. Ovaries were fixed in neutral formaldehyde solution for 24 hours and embedded with paraffin. Cutted in $5{\mu}m$ thickness with microtome and stained with hematoxylin and eosin (H&E) and TUNEL immunohistochemical stain, and examined histologically under a light microscope. All data were presented as mean ${\pm}SD$, calculating the ratio of normal or atretic follicles to total ovarian follicles. Statistical analysis was performed by the Mann Whitney test using the SPSS ver 19.0. Ratio of atretic to total follicles of 2 Gy group was significantly higher than control or 2 cGy groups (p<0.05). Ratio of normal to total follicles of 2 Gy group was significantly lower than control group in preantral follicle (64.0 vs. 87.7, p=0.027). Ratio of normal to total follicles of 2 cGy group was significantly increased more than control or 2 Gy groups in antral follicle, and there were no significant difference between control and 2 Gy groups (p=0.522). Radiation dose of 2 Gy for cancer radiotherapy have a significant effect on ovarian follicle atresia in rat.

• Journal of radiological science and technology
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• v.26 no.1
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• pp.45-50
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• 2003

In this work, we characterized the shieldability and lightweight of radiation protective aprons which were consisted of various metal(Pb, Sn, Ni, Ti and Cu) by measuring the x-ray dose transmitted through the filters. The transmitted ratio and lead equivalent of various metal were obtained by linear interpolation and the lead equivalent of double layered filters contained Pb layer was determined. The transmitted ratio of the apron(0.25 mmPb) specified in KS B 0845 was 5.2%. The transmitted ratio of the filters at the thickness of 0.6 mm was decreased in the other of Ni(32.60%), Ti(17.75%), Cu(13.25%) and Sn(3.84%). From the results of experimental evaluation for combined filter of Pb and Sn, it was founded that in the case of the first Sn layer, the lead equivalent was higher than that of the first Pb layer. The lead equivalent corresponding to apron of 0.25 mmPb was obtained in the double layered filters of Sn(0.19 mm) - Pb(0.1 mm) and Pb(0.1 mm) - Sn(0.37 mm). Thus, the Sn-Pb filter had the lower weight about 13% than apron of 0.25 mmPb.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1171-1178
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• 2023

In study, we investigated changes on growth and chlorophyll concentration on sprouted barley by fractionated X-ray irradiation (FXI). Group was divided into the control group (CG), 1-time irradiation group (30 Gy once), 2-time irradiation group (15 Gy 2 times), and 3-time irradiation group (10 Gy 3 times), and 20 grains were used per group. Experimental group (EG) was exposed by using linear accelerator (Clinac IS, VERIAN, USA), by 6 MV X-ray, SSD 100 cm, 18×10 cm², 600 MU/min. Length was measured every day until 9th day, and chlorophyl was analyzed using spectrophotometer(uv-1800, shimadzu, japan) in 9th day. Data analysis was performed the One-way ANOVA using SPSS ver 26.0(Chicago, IL, USA). In the pre-germination irradiation group (Pre-GIG), the CG had greater length than the EG on all measurement days, and as the number of FXI increased, the length became shorter. In the post-germination irradiation group (Post-GIG), the length of the CG was statistically significantly greater than that of the EG on all measurement days, and as the number of FXI increased, the length also became longer. The chlorophyll concentration was higher in the Post-GIG than in the Pre-GIG, and chlorophyll concentrations of EG was higher in the Pre-GIG than in the CG, as well as and Post-GIG. In addition, the smaller the number of FXI, the higher the chlorophyll concentration in both groups. FXI was found to affect the growth and chlorophyll concentration of sprouted barley.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.91-98
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• 2023

PET is used effectively for biochemical or pathological phenomena, disease diagnosis, prognosis determination after treatment, and treatment planning because it can quantify physiological indicators in the human body by imaging the distribution of various biochemical substances. However, since respiratory motion artifacts may occur due to the movement of the diaphragm due to breathing, we would like to evaluate the practical effect by using the a device-less data-driven gated (DDG) technique called MotionFree with the phase-based gating correction method called Q.static scan mode. In this study, images of changes in moving distance (0 cm, 1 cm, 2 cm, 3 cm) are acquired using a breathing-simulated moving phantom. The diameters of the six spheres in the phantom are 10 mm, 13 mm, 17 mm, 22 mm, 28 mm, and 37 mm, respectively. According to maximum standardized uptake value (SUVmax) measurements, when DDG was applied based on the moving distance, the average SUVmax of the correction effect by the moving distance was improved by 1.92, 2.48, 3.23 and 3.00, respectively. When DDG was applied based on the diameter of the phantom spheres, the average SUVmax of the correction effect by the moving distance was improved by 2.37, 2.02, 1.44, 1.20, 0.42 and 0.52 respectively.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.149-156
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• 2023

The purpose of this study is to compare of growth and chlorophyl between old-barley seed (OBS, 2019) and New-barley seed (NBS, 2020) exposed by X-ray. After germination the OBS and NBS, experimental group was exposed by 30 Gy X-ray using linear accelerator (Clinac IS, VERIAN, USA), by 6 MV X-ray, SSD 100 cm, 18 × 10 cm², 600 MU/min. Length was measured every day until 9th day, and chlorophyl was analyzed using spectrophotometer(uv-1800, shimadzu, japan) after measuring weight in 9th day. Data analysis was performed the Independent T-test using SPSS ver 26.0(Chicago, IL, USA). NBS grow more faster than OBS in control group, but OBS grow more faster than NBS in experimental group. Length of control group was longer significantly every day than that of experimental group in OBS. NBS weighted more than OBS in control group, but OBS weighted more than NBS in experimental group. In comparing chlorophyl density, NBS high more than OBS in control group as well as experimental group. Growth and weight of OBS was effected more those than NBS by X-ray, but NBS in chlorophyl by X-ray. It is expected to be used as basic data for future X-ray research in barley seed.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.125-153
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• 2005

It has been widely known that the seismic piezo-cone penetration test (SCPTU) is one of the most useful techniques for investigating the geotechnical characteristics including dynamic soil properties. As the practical applications in Korea, SCPTU was carried out at two sites in Busan and four sites in Incheon, which are mainly composed of alluvial or marine soil deposits. From the SCPTU waveform data obtained from the testing sites, the first arrival times of shear waves were and the corresponding time differences with depth were determined using the cross-over method, and the shear wave velocity profiles (VS) were derived based on the refracted ray path method based on Snell's law and similar to the trend of cone tip resistance (qt) profiles. In Incheon area, the testing depths of SCPTU were deeper than those of conventional down-hole seismic tests. Moreover, for the application of the conventional CPTU to earthquake engineering practices, the correlations between VS and CPTU data were deduced based on the SCPTU results. For the empirical evaluation of VS for all soils together with clays and sands which are classified unambiguously in this study by the soil behavior type classification Index (IC), the authors suggested the VS-CPTU data correlations expressed as a function of four parameters, qt, fs, $\sigma$, v0 and Bq, determined by multiple statistical regression modeling. Despite the incompatible strain levels of the down-hole seismic test during SCPTU and the conventional CPTU, it is shown that the VS-CPTU data correlations for all soils clays and sands suggested in this study is applicable to the preliminary estimation of VS for the Korean deposits and is more reliable than the previous correlations proposed by other researchers.