• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.12
• /
• pp.147-151
• /
• 2016

Automatic exposure control (AEC) is frequently used in many hospitals for Standing Whole Spine examination which is able to control radiation dose with respect to the body type such as body mass index (BMI) and we can measure dose area product (DAP) based on respective patient information. However, few studies have been conducted organ absorbed dose evaluation based on location of patient organ. The purpose of this study was to evaluate the relationships between BMI and organ absorbed dose along with location of patient organ. For that purpose, we calculated absorbed dose with selected 5 patient organ (thyroid, breast, heart, kidney, and pancreas) using a PCXMC simulation tool with measured DAP. According to the results, measured DAP increases with BMI and organ absorbed dose decreases with BMI in anterior organs such as thyroid, breast, and heart. On the other hand, there is no correlation between organ absorbed dose and BMI in posterior organs such as kidney and pancreas. In conclusion, our results demonstrated that the radiation effects are different with respect to BMI and location of patient organ in Standing Whole Spine examination.

• Journal of radiological science and technology
• /
• v.41 no.5
• /
• pp.391-396
• /
• 2018

The purpose of this study was to compare and analyze the patient dose according to the distance between the X-ray tube focus and the image receptor, and to propose a new method for quantitatively evaluating the image quality. Using this quantitative evaluation method, the optimal distance for increasing x-ray image quality with low radiation dose was estimated between source and image receptor in Rib series radiography. Phantom images were obtained by changing the distance between focus and image receptor (100 cm and 180 cm). The patient radiation dose was estimated using entrance surface dose and dose area product. In order to evaluate image quality objectively, a non - reference image evaluation method was employed with paper and salt noise and Gaussian filter. As a result of this study, when the SID was changed from 100 cm to 180 cm, the entrance surface dose decreased by 4 ~ 5 times and the dose area product decreased by 3 times. In addition, there is no significant difference in image quality between of SID 180 cm and SID 100 cm. In conclusion, it was demonstrated that performing the rib series radiography at SID 180 cm is an optimal method to reduce the exposure dose and improve the image quality.

• Journal of the Korean Society of Radiology
• /
• v.11 no.3
• /
• pp.117-122
• /
• 2017

With the increase in leisure life, the population of ski resorts is rapidly increasing. The activity at the ski resort is likely to receive a direct chance of natural sunlight or space ray. Because it is located in the mountains where altitude exists. As a general rule, it is widely known that the higher the elevation rate, the more increasing the natural radiation dose. However, the natural radiation dose rate for the ski slopes has not been reported yet. Various ski resorts exist in Korea, but this study had chose 4 ski resorts to measure the natural dose of natural radiation. As a result, the natural radiation dose for the ski slope was measured at a relatively high dose of ordinary living areas. However, the level of natural radiation dose was not worrisome. It is recommended to wear ski wear or goggles to minimize natural radiation exposure at the ski slopes.

• Journal of the Korean Society of Radiology
• /
• v.15 no.2
• /
• pp.139-145
• /
• 2021

This study is to confirm the range of tube voltage for Chest X-ray in DR system by comparing with dose area product (DAP) and effective dose in efficient detector exposure index (DEI) range. GE definium 8000 was used to for the phantom study. The range of tube voltage is 60~130 kVp and of mAs is 2.5~40 mAs. The acquired images were classified into efficient DEI groups, then calculated effective dose with DAP by using a PC-Based Monte Carlo Program 2.0. The signal to noise ratio (SNR) was measured at 4 regions, including the thoracic spine, the lung area with the ribs, the lung area without the ribs, and the liver by using Picture Archiving and Communication System. The significance of the group for each tube voltage was verified by performing the kruskal-wallis test and the mann-whitney test as a post-test. When set to 4 groups dependned on the tube voltage, DAP showed significant differences; 60 kVp and 80 kVp, and 60 kVp and 90 kVp (p= 0.034, 0.021). Effective dose exhibited no statistically significant differences from the all of the group (p>0.05). SNR exhibited statistically significant differences from the all of the group in the liver except compared to 80 kVp and 90 kVp (p<0.05). Therefore, high tube voltages of 100 kVp or more need to be reconsidered in terms of patient dose and imaging in order to represent an appropriate chest X-ray image in a digital system.

• The Journal of Engineering Geology
• /
• v.30 no.4
• /
• pp.577-588
• /
• 2020

We evaluated the distributions of primordial radionuclides and effective dose rate of the Ogcheon Group, which includes rocks with high uranium content. Terrestrial gamma radiation was measured at 421 points using a portable gamma ray spectrometer. Dividing the study area into five geological units (og1, og2, og3, og4, and igneous rocks) revealed no significant difference in the concentration of surface radioactivity among the types. The concentrations of 40K, eU, and eTh for all samples ranged from 0.7% to 10.3% (average 5.2%), 0.6 to 287.0 ppm (average 8.5 ppm), and 4.0 to 102.4 ppm (average 31.3 ppm), respectively. The absorbed dose rate in the study area (calculated from the activity concentrations of 40K, eU, and eTh) was in the range of 28.84 to 1,714.5 nGy/h (average 195.4 nGy/h). Among the five geological units, the lowest average was 166.3 nGy/h (for og1) and the highest average was 233.3 nGy/h (for og2; median 198.1 nGy/h). The outdoor effective dose rate for the area obtained from the absorbed dose rate was in the range of 0.04 to 2.10 mSv/y (average 0.24 mSv/y). Except for the four sites located in the uranium-bearing coal bed of og2, none of the studied sites exceeded 1 mSv/y.

• The Journal of Korean Society for Radiation Therapy
• /
• v.14 no.1
• /
• pp.175-186
• /
• 2002

The purpose of this study is directly measure and evaluate about absorbed dose change according to nominal energy and electron cone or medical accelerator on isodose curve, percentage depth dose, contaminated X-ray, inhomogeneous tissue, oblique surface and irradiation on intracavitary that electron beam with high energy distributed in tissue, and it settled standard data of hish energy electron beam treatment, and offer to exactly data for new dote distribution modeling study based on experimental resuls and theory. Electron beam with hish energy of $6{\sim}20$ MeV is used that generated from medical linear accelerator (Clinac 2100C/D, Varian) for the experiment, andwater phantom and Farmer chamber md Markus chamber und for absorbe d dose measurement of electron beam, and standard absorbed dose is calculated by standard measurements of International Atomic Energy Agency(IAEA) TRS 277. Dose analyzer (700i dose distribution analyzer, Wellhofer), film (X-OmatV, Kodak), external cone, intracavitary cone, cork, animal compact bone and air were used for don distribution measurement. As the results of absorbed dose ratio increased while irradiation field was increased, it appeared maximum at some irradiation field size and decreased though irradiation field size was more increased, and it decreased greatly while energy of electron beam was increased, and scattered dose on wall of electron cone was the cause. In percentage depth dose curve of electron beam, Effective depth dose(R80) for nominal energy of 6, 9, 12, 16 and 20 MeV are 1.85, 2.93, 4.07, 5.37 and 6.53 cm respectively, which seems to be one third of electron beam energy (MeV). Contaminated X-ray was generated from interaction between electron beam with high energy and material, and it was about $0.3{\sim}2.3\%$ of maximum dose and increased with increasing energy. Change of depth dose ratio of electron beam was compared with theory by Monte Carlo simulation, and calculation and measured value by Pencil beam model reciprocally, and percentage depth dose and measured value by Pencil beam were agreed almost, however, there were a little lack on build up area and error increased in pendulum and multi treatment since there was no contaminated X-ray part. Percentage depth dose calculated by Monte Carlo simulation appeared to be less from all part except maximum dose area from the curve. The change of percentage depth dose by inhomogeneous tissue, maximum range after penetration the 1 cm bone was moved 1 cm toward to surface then polystyrene phantom. In case of 1 cm and 2 cm cork, it was moved 0.5 cm and 1 cm toward to depth, respectively. In case of air, practical range was extended toward depth without energy loss. Irradiation on intracavitary is using straight and beveled type cones of 2.5, 3.0, 3.5 $cm{\phi}$, and maximum and effective $80\%$ dose depth increases while electron beam energy and size of electron cone increase. In case of contaminated X-ray, as the energy increase, straight type cones were more highly appeared then beveled type. The output factor of intracavitary small field electron cone was $15{\sim}86\%$ of standard external electron cone($15{\times}15cm^2$) and straight type was slightly higher then beveled type.

• Nuclear Engineering and Technology
• /
• v.52 no.5
• /
• pp.956-963
• /
• 2020

Dose optimization for Radioactive Occupational Personal (ROP) is an important subject in nuclear and radiation safety field. The geometric environment of a nuclear facility is complex and the work area is radioactive, so traditional navigation model and radioactive data field cannot form an effective environment model for dose assessment and dose optimization. The environment model directly affects dose assessment and indirectly affects dose optimization, this is an urgent problem needed to be solved. Therefore, this paper focuses on an environment model used for Dose Assessment and Dose Optimization (DA&DO). We designed a multi-layer radiation field coupling modeling method, and then explored the influence of the environment model to DA&DO by virtual simulation. Then, a simulation test is done, the multi-layer radiation field coupling model for nuclear facilities is demonstrated to be effective for dose assessment and dose optimization through the experiments and analysis.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2003.11a
• /
• pp.497-502
• /
• 2003

Landfill is an widely applied alternative for clearance of non-contaminated waste or slightly contaminated waste generated from nuclear facilities. In this study, exposure dose is estimated for a worker and a resident at the landfill area in Young-gwang nuclear power plant. Based on evaluated dose, clearance concentrations of each radionuclide are determinated for dose criteria of 10 $\muSv/y$. The results of age-dependent dose are 1.02 $\muSv$ per year for resident and 0.471 $\muSv$ per year for worker. Clearance concentrations for each radionuclide are evaluated from $1.33{\times}10_{-1}$ Bq per gram to $2.85{\times}10^2$ Bq per gram.

• Journal of radiological science and technology
• /
• v.47 no.1
• /
• pp.13-19
• /
• 2024

Control of scattered radiation is one of very important factors in the use of medical radiation. In general X-ray exam, the causes, measurement methods, and the kind of detectors of scattered rays within the radiation area are diverse. In this study, the dose of scattered ray was measured by changing the thickness of the polycarbonate phantom and the tube voltage. As a result of measurement of scattered radiation, the results show that the scattered dose significantly(p<.05) increased with growing of thickness of phantom in the tube voltage 40, 50 and 60 kVp(F(p)<.05, R²>64%). As tube voltage increased at all phantom thicknesses, the scattered dose also significantly(p<.05) increased(F(p)<.05, R²>69%). In cases where a significant correlation was shown, the coefficient of determination of more than 60% was shown in regression analysis. The results of this study can be used as data on scattered radiation dose according to the tube voltage and the object thickness in general X-ray imaging exam.

• Journal of Institute of Control, Robotics and Systems
• /
• v.9 no.4
• /
• pp.296-303
• /
• 2003

A personal portable type electronic dosimeter using silicon PIN photodiode and small GM tube is recently attracting much attention due to its advantages such as an immediate indication function of dose and dose rate, alerting function, and efficient management of radiation exposure history and dose data. We designed and manufactured a semiconductor radiation detector aimed to directly measure X-ray and v-ray irradiated in silicon PIN photodiode, without using high-priced scintillation materials. Using this semiconductor radiation detector, we developed an active electronic dosimeter, which measures the exposure dose using pulse counting method. In this case, it has a shortcoming of over-evaluating the dose that shows the difference between the dose measured with electronic dosimeter and the dose exposed to the human body in a low energy area. We proposed an energy compensation filter and developed a dose conversion algorithm to make both doses indicated on the detector and exposed to the human body proportional to each other, thus enabling a high-precision dose measurement. In order to prove its reliability in conducting personal dose measurement, crucial for protecting against radiation, the implemented electronic dosimeter was evaluated to successfully meet the IEC's criteria, as the KAERI (Korea Atomic Energy Research Institute) conducted test on dose indication accuracy, and linearity, energy and angular dependences.