• Journal of radiological science and technology
• /
• v.3 no.1
• /
• pp.81-86
• /
• 1980

To compare three-phase 12-pulse full-wave X-ray generators with single-phase full-wave X-ray generators on their performance of outputs, authors studied the generating X-ray by means of exposure dose and radiographic density. The results were as follows; 1. The exposure doses of three-phase full-wave X-ray generators showed a 30%-60% increase as compared against of single-phase full-wave generators. 2. The transmitted doses of three-phase full-wave generators were more increased than single-phase full-wave X-ray generators. 3. To obtain the same density, 60kVp in three-phase full-wave generators were equivalent to $60{\sim}65kVp$ in single-phase full-wave generators, and 100kVp in those generators were equivalent to $100{\sim}125kVp$ in these generators.

• Journal of Radiation Industry
• /
• v.11 no.3
• /
• pp.123-130
• /
• 2017

Concerns about high radiation exposure to the hands of radiation workers who may contact with radioactive contamination on surfaces in a nuclear power plant (NPP) had been raised, and the Korean regulatory body required the extremity dose estimation during contact tasks with radioactive materials. Korean NPPs conducted field tests to identify the incident radiation to the hands of radiation workers who may contact with radioactive contamination during maintenance periods. The results showed that the radiation fields for contact tasks are dominated by high energy photons. It was also found that the radiation doses to the hands of radiation workers in Korean NPPs were much less than the annual dose limits for extremities. This approach can be applicable to measure and estimate the extremity dose to the hands of medical workers who handle the radioactive materials in a hospital.

• Journal of radiological science and technology
• /
• v.46 no.5
• /
• pp.409-415
• /
• 2023

Although pediatric X-ray examinations are continuously increasing, there are not many studies on the radiation exposure to children and X-ray examination assistants according to X-ray Exposure conditions. Accordingly, we measured the radiation exposure dose of pediatric and X-ray examination assistants according to the standard guidelines and clinical average X-ray Exposure conditions when X-ray examination 10-year-old children. The effective dose and organ dose to pediatric were measured using an Dose area production meter and Monte Carlo-based PCXMC program, and the exposure dose of X-ray examination assistants was measured using an ion-chamber. When performing abdominal supine AP projection, the effective dose to children was up to 2.38 times higher under clinical average X-ray Exposure conditions than the standard guidelines. In addition, during abdominal supine AP projection, the radiation exposure dose to the X-ray examination assistants was highest on the hands at 0.0148 ~ 0.0709 mSv, and exposure dose could be reduced by up to 35% when wearing protective gloves. In conclusion, because the X-ray Exposure conditions used in clinical are unnecessarily high, unnecessary medical radiation exposure could be reduced if appropriate X-ray Exposure conditions and the radiation field area were minimized and the assistant wore shielding gloves.

• Journal of Radiation Protection and Research
• /
• v.45 no.1
• /
• pp.2-10
• /
• 2020

Background: Huge amounts of radionuclides were released into the environment due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, which caused not only serious contamination on the ground, but also radiation exposure to the public. One problem that remains in performing the dose estimation is the difficulty of estimating the internal thyroid dose due to the intake of radioiodine (mainly, ¹³¹I) because of limitations to the human data available. Materials and Methods: The relevant papers were collected and reviewed by the authors. The results of thyroid dose estimates from different studies were tabulated for comparison. Results and Discussion: The thyroid dose estimates from the studies varied widely. The dose estimates by the United Nations Scientific Committee on the Effects of Atomic Radiation were higher than the others due to the ingestion dose being based on conservative assumptions. The dose estimates by Japanese experts were mostly below 20-30 mSv. The recent studies suggested that exposure on March 12, 2011 would be crucial for late evacuees from the areas near the FD-NPP because of the possible intake of short-lived radionuclides other than ¹³¹I. Further multilateral studies are vital to reduce uncertainties in the present dose estimations. Conclusion: The estimation of the thyroid doses to Fukushima residents still has many uncertainties. However, it is considered unlikely that the thyroid doses exceeded 50 mSv except in some extreme cases. Further multilateral studies are thus necessary to reduce the uncertainties in the present dose estimations.

• Journal of Radiation Protection and Research
• /
• v.39 no.4
• /
• pp.213-217
• /
• 2014

Medical operations and diagnosis using interventional radiology techniques have been increased. The management and monitoring of occupational radiation exposure to the staff of interventional radiology become important, specially because they stand in close proximity to the patient. The operational radiation protection quantity, Hp(10) which can be obtained from personal dosimeter do not always represent the effective dose to the staff. So, in this study, to estimate the critical organ doses to the staff of interventional radiology, Monte Carlo calculations with mathematical human phantom and dose measurements with personal dosimeters were carried out for the major interventional radiology procedures using C-arm. Results showed that the values of Hp(10) measured by personal dosimeters were higher than critical organ doses which were calculated. And the calculated dose to thyroids was much higher than those of other critical organ doses. For the proper radiation protection of the medical staff of interventional radiology, additional radiation protection for thyroids as well as for whole body shielding like wearing a lead apron should be considered.

• Nuclear Engineering and Technology
• /
• v.55 no.5
• /
• pp.1935-1945
• /
• 2023

The radiological safety of workers in a newly developed microwave-based spent resin treatment facility was assessed based on work location and operational scenarios. The results show that the remote-operation room worker was exposed to maximum annual dose of 3.19E+00 mSv, which is 15.9% of the dose limit, thereby confirming radiological safety. Inside the pathway, annual doses in the range of 7.87E-02-2.07E-01 mSv were measured initially at the mock-up tank and later at the point between the spent resin separation and treatment parts. The dose of emergency maintenance workers was below the dose limit (4.08E-03-4.99E+00 mSv); however, before treatment (separation and microwave), the dose of maintenance and repair workers exceeded the dose limit. The doses of the effluent removal workers at the zeolite and activated carbon storage tank and spent resin storage tank were the lowest at 2.79E-01-2.87E-01 mSv and 9.27E-01 mSv in "1 h" and "4-5 h of operation", respectively. The immediately lower and upper layers of the facility room exhibited the highest annual doses of 1.84E+00 and 3.22E+00 mSv, respectively. Through this study, a scenario that can minimize the dose considering the movement of spent resin through the facility can be developed.

• Journal of the Korean Society of Radiology
• /
• v.13 no.2
• /
• pp.147-151
• /
• 2019

In chest and abdomen CT scans, the radiation exposure doses by scattering lines were measured at the eyeball and thyroid. Radiation exposure was investigated by using shielding devices. The chest and abdomen CT scan protocols used in the real examination were applied to measure and compare radiation doses before and after the use of shielding devices at the eyeball and the thyroid. The radiaton doses were measured with OSLD dosimeters. Barium, tungsten sheets, goggles and neck shields were used to protect the scattered X-ray. The chest CT scans showed respectively 3.01 mSv and 6.21 mSv at the eyeball and the thyroid by the scattered X-ray. The abdomen CT scans showed 0.55 mSv and 3.22 mSv for the eyeball and the thyroid respectively. Barium and tungsten sheets had 11% to 13% protection rates at the eyeball and the thyroid for chest CT scan, and 34% to 49% reduction in radiation dose for the abdomen CT scan. Because of the significant radiation dose, which causes cataracts and thyroid cancer by the repeated and continuous radiation exposure, for the chest and the abdomen CT scans, it is required to use shielding devices to reduce radiation dose for examinations.

• Journal of the Korean Society of Radiology
• /
• v.17 no.2
• /
• pp.191-199
• /
• 2023

This study aimed to propose minimized radiation doses with an optimized abdomen x-ray image, which realizes a Deep Blind Image Super-Resolution Generative adversarial network (BSRGAN) technique. Entrance surface doses (ESD) measured were collected by changing exposure conditions. In the identical exposures, abdominal images were acquired and were processed with the BSRGAN. The images reconstructed by the BSRGAN were compared to a reference image with 80 kVp and 320 mA, which was evaluated by mean squared error (MSE), peak signal-to-noise ratio (PSNR), and structural similarity index measure (SSIM). In addition, signal profile analysis was employed to validate the effect of the images reconstructed by the BSRGAN. The exposure conditions with the lowest MSE (about 0.285) were shown in 90 kVp, 125 mA and 100 kVp, 100 mA, which decreased the ESD in about 52 to 53% reduction), exhibiting PSNR = 37.694 and SSIM = 0.999. The signal intensity variations in the optimized conditions rather decreased than that of the reference image. This means that the optimized exposure conditions would obtain reasonable image quality with a substantial decrease of the radiation dose, indicating it could sufficiently reflect the concept of As Low As Reasonably Achievable (ALARA) as the principle of radiation protection.

• Korean Journal of Environmental Biology
• /
• v.21 no.4
• /
• pp.321-327
• /
• 2003

Differences between the principles for the radiological protection of man and the environment are compared. The derived levels of exposure for man and biota recommended by the international agencies with dose rates for chronic radiation producing effects at different levels of biological organization were given in terms of the biological effects. Cytogenetic effects on plants after an exposure to ionizing radiation at low doses alone and in combination with other factors are discussed. A wide range of experimental data were analysed and the general conclusions were extracted to cover the topics such as non-linearity of dose response, synergistic and antagonistic effects of the combined exposure of different factors, radiation-induced genomic instability, and the phenomena of radioadaptation.

• Journal of radiological science and technology
• /
• v.17 no.1
• /
• pp.49-54
• /
• 1994

This study was conducted to find out the medical exposure dose in simple abdomen A-P projection of adults, based on the 87 hospitals located in Seoul. As the results, the following conclusions have been reached; 1. 88.5 % of the surveyed hospitals had the use of $65\;kVp{\sim}79\;kVp(M{\pm}SD:71.45{\pm}4.73\;kVp)$ as tube voltage. 2. 87.35 % of the surveyed hospitals had the use of $50\;mAs{\sim}89\;mAs(M{\pm}SD:64.31{\pm}16.21\;mAs)$ as the amount of current. 3. Shallow doses ranged from 2.00 mSv to 4.99 mSv($M{\pm}SD:3.81{\pm}1.01\;mSv$) in 80.46 % of the surveyed hospitals. 4. Exposure dose was directly depended on the tube voltage or the amount of currents.