• Korean Journal of Environmental Agriculture
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• v.21 no.3
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• pp.202-207
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• 2002

To establish the seed treatment method of the gamma radiation for germination enhancement of bottle gourd(Lagenaria siceraria Standl.) and pumpkin(Cucurbita ficifolia Bouche), seeds were irradiated with the dose of 1$\sim$20 Gy of the gamma radiation. The germination rate in irradiated group was higher than that of the control, depending on seed condition. In the case of bottle gourd, the germination rate of 70$\sim$80% germinative seed was increased at 4$\sim$20 Gy irradiated groups. Especially, it was the highest at 4 Gy irradiated group. The germination rate of 80$\sim$90% germinative seed was the highest at 4 Gy irradiated group. The germination rate of 70$\sim$80% and 80$\sim$90% germinative seed at 4 days after sowing was increased 66% and 26% at 4 Gy irradiated group, respectively. In the case of pumpkin, the germination rate of 70$\sim$80% and 80$\sim$90% germinative seed was increased at 2 Gy and 8 Gy irradiated group, respectively. Effect of the low-dose gamma radiation on the early growth was enhanced depending on their germination enhancement. Especially, it was the highest at 2 Gy irradiated group of 70$\sim$80% germinative seed of pumpkin. Catalase activity of bottle gourd was increased at 4 Gy irradiated group. Catalase and peroxidase activity of pumpkin were increased at 2 Gy and 8 Gy irradiated group. These results suggest that the germination, early growth and physiological activity of bottle gourd and pumpkin seeds could be promoted by the low dose gamma radiation.

• Progress in Medical Physics
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• v.5 no.2
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• pp.57-68
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• 1994

Purpose : The purposes are to discuss the reason to measure dose distributions of circular small fields for stereotactic radiosurgery based on medical linear accelerator, finding of beam axis, and considering points on dosimetry using home-made small water phantom, and to report dosimetric results of 10MV X-ray of Clinac-18, like as TMR, OAR and field size factor required for treatment planning. Method and material : Dose-response linearity and dose-rate dependence of a p-type silicon (Si) diode, of which size and sensitivity are proper for small field dosimetry, are determined by means of measurement. Two water tanks being same in shape and size, with internal dimension, 30${\times}$30${\times}$30cm$^3$ were home-made with acrylic plates and connected by a hose. One of them a used as a water phantom and the other as a device to control depth of the Si detector in the phantom. Two orthogonal dose profiles at a specified depth were used to determine beam axis. TMR's of 4 circular cones, 10, 20, 30 and 40mm at 100cm SAD were measured, and OAR's of them were measured at 4 depths, d$\sub$max/, 6, 10, 15cm at 100cm SCD. Field size factor (FSF) defined by the ratio of D$\sub$max/ of a given cone at SAD to MU were also measured. Result : The dose-response linearity of the Si detector was almost perfect. Its sensitivity decreased with increasing dose rate but stable for high dose rate like as 100MU/min and higher even though dose out of field could be a little bit overestimated because of low dose rate. Method determining beam axis by two orthogonal profiles was simple and gave 0.05mm accuracy. Adjustment of depth of the detector in a water phantom by insertion and remove of some acryl pates under an auxiliary water tank was also simple and accurate. TMR, OAR and FSF measured by Si detector were sufficiently accurate for application to treatment planning of linac-based stereotactic radiosurgery. OAR in field was nearly independent of depth. Conclusion : The Si detector was appropriate for dosimetry of small circular fields for linac-based stereotactic radiosurgery. The beam axis could be determined by two orthogonal dose profiles. The adjustment of depth of the detector in water was possible by addition or removal of some acryl plates under the auxiliary water tank and simple. TMR, OAR and FSF were accurate enough to apply to stereotactic radiosurgery planning. OAR data at one depth are sufficient for radiosurgery planning.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.813-819
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• 2021

In this study, the shielding rate of L-block-type shielding equipment used for radiation protection when radioactive fluorine is injected into the human body and the dose distribution of the space in the injection room were calculated using the Monte Carlo method. The shielding rate of the body and window parts of the L-block-type shielding equipment was 99.99%. The dose distribution calculated at a distance of 1 m was relatively high at 135°, 45°, 225°, 315°, and 180° of the XZ plane, and was calculated to be very low at 0°, 90°, and 270°. In the YZ plane, it was relatively high at 135°, 180°, and 225°, and was calculated very low at the remaining angles. The AZ and BZ planes also showed similar results to the YZ plane. In addition, it was confirmed that the shielding rate was the best in the range of 225° to 315° through the dose distribution in the horizontal direction of the source and the 45° direction above the source. These results can be used as basic data necessary for radiation protection of radiation workers.

• Journal of Radiation Protection and Research
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• v.27 no.2
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• pp.77-80
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• 2002

A more practice approach for the determination of monetary values of the unit collective dose for intervention against long-term exposure following a nuclear accident was proposed. In addition, she monetary values of the unit collective dose estimated from the proposed approach were compared with those estimated from the previous model, which are derived from assumptions of routine exposure and the same values are applied in a nuclear accident without modification, using Korean economic data. The monetary values based on the proposed approach showed a distinct difference depending on inequity in the distribution of individual doses. The discounting rate was also an important factor in determination of monetary values of the unit collective dose.

• Journal of the Korean Society of Radiology
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• v.12 no.4
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• pp.467-474
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• 2018

CBCT is useful for improving the accuracy of the treatment site, but Repeated use increases the exposure dose. In this study, we aimed to provide basic data for dose reduction in CBCT implementation by dataization the simulating and dose reduction effect using shielding substance. Material in this study, Analyzation the photon beam by simulate the CBCT Through MCNPX and then calculate the absorption dose of body organ at shooting moment of thoracic abdominal position as target UF-Revise simulated body. At this time. Dose reduction effects at this time were evaluated according to the texture of materials and presence of shielding materials( lead, antimony, barium, sulfate, tungsten, bismuth). When CBCT was taken without shielding, the dose was calculated to be high in the breast and spine, and the dose in the esophagus and lung was calculated to be low. The doses according to the shield material were calculated as barium sulfate, antimony, bismuth, lead, and tungsten. The shielding rate was the highest in the thymus (73.6%) and the breast (59.9%) compared with the dose reduction according to presence or absence of the shield. However, it showed the lowest shielding rate in lung (2.1%) and spine (12.6%).

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.1 no.2
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• pp.57-61
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• 1987

The characteristis of all the instruments and materials used in atomic industry are changed due to irradiation damages by the effects of radiation activities. In this study when R-C series-parallel circuits are irradiated by $\gamma$-ray, variations in its electrical properties have been investigated. The following results are obtained. 1) In the R-C series circuit, the impedance variation ratio is increased as the irradiation quantity is increased up to $10^6[r]$, and above $10^6[r]$, the impedance variation ratio reached at the saturated condition. In the saturated condition, the increasing value was about 1.25 (%). 2) In the R-C series circuit, the power factor variation ratio is decreased as the irradiation quantity is in creased up to $10^6[r]$, and above $10^6[r]$, the power factor variation ratio reached at the saturated condition. In the saturated condition, the decreasing value was about 0.5(%). 3) In the R-C parallel circuit, the impedance variation ratio is increased as the irradiation quentity is increased up to $10^6[r]$, and above $10^6[r]$, the impedance variation reached at the saturated condition. In the saturated condition, the increasing value was about 0.5.(%). 4) In the R-C parallel circuit, the power factor variation ratio is decreased as the irradiation quantity is increased up to $10^6$[r], and above $10^6$[r], the power factor variation ratio reached at the saturated condition. In the saturated condition, the decreasing value was about 1.3(%).

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.25-28
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• 2012

Purpose : It is important to reduce radiation dose associated with computed tomography (CT) scanning to as low as reasonably achievable (ALARA). With Dose Modulation Technic, user select a desired image quality and the system adapts tube current to obtain the desired image quality with greater radiation dose efficiency. In this paper, we presents a comprehensive description of fundamentals, clinical applications and radiation dose benefits of Dose Modulation Technic depending on Body Mass Index(BMI). Materials and Methods : In this study, 149 patients were examined(The mean age : $58{\pm}12.4$ years old). Biograph True Point 40 (Siemens, USA) and Gemini TF 64 (Philips. Cleveland) were used for equipment. When we used Care Dose 4D (Siemens, USA) and D-dom (Philips, Cleveland), we measured dose reduction and Computed Tomography Dose Index (CTDI) depending on BMI. Then we analyze data using SPSS Ver.18. Results : When we used Care Dose 4D, p-value is considered statistically significant by groups with the result that we compared Care Dose 4D with D-dom. On the other hand, p-value isn't considered statistically significant by groups using D-dom. Conclusion : Dose modulation based on the projection angle didn't affect degree of obesity. And When using Care Dose 4D, dose reduction rate in the normal patients were higher than the obese. In this study, there are errors on somato type. So I think more research have to be done. Then application of Dose Modulation technic can help in maintaining acceptable image quality while reducing radiation dose by 20-60% in most instances.

• Journal of The Korean Radiological Technologist Association
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• v.27 no.2
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• pp.57-65
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• 2001

This study was performed to measure about exposure dose during simple abdomen x-ray Radiography. The exposure dose was measured by PDD, surface dose, percentage scatter dose, respectively. The result was as followed: 1. When tube voltage were increased wi

• Progress in Medical Physics
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• v.6 no.1
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• pp.49-57
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• 1995

The semiconductor detector has a high sensitive to radiation and a small volume. It has been frequently used in high energy photon and electron beamdosimetry. However, Semiconductor detector are subject to radiation damage in high energy radiation beam which reduces the sensitivity and creat a large discrepancy. In this experiments, P-type semiconductor was irradiated to 18 MeV electron beam with pre-irradiation for reducing the sensitivity for high reproducibility and investigated the dose characteristics against the dose rate variations. The sensitivity per unit dose in small dose rate showed a 35％ large different to a large dose rate with pre-irradiation dose for 0.5 KGy and 20％ for 3 KGyin this study. The silicon detector has showed a large dependency of beam direction with 13％ discrepancy and a linear sensitive as increased temperature.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.71-77
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• 2001

Pepper (Capsicum annuum L. cv. Jokwang and cv. Johong) seeds were irradiated with the doses of 0-50 Gy to investigate the effect of the low dose ${\gamma}$-radiation on the early growth and resistance to subsequent high dose of radiation. Following effect was observed in Johong cultivar but not in Jokwang cultivar Germination and early growth rate of Johong cultivar were noticeably increased at 4, 8 and 20 Gy irradiation group. Resistance to subsequent high dose of radiation of Johong cultivar increased at almost all of the low dose irradiation group. Especially it was highest at 4 Gy irradiation group. Plant groups of Johong cultivar showing the resistance to subsequent high dose of radiation, which had been pre-irradiated with 4 Gy and 8 Gy, were also higher in the carotenoid contents and enzyme activity than the plant group not irradiated previously.