• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.149-157
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• 2018

One of the purposes of radiation protection is to minimize stochastic effects. PCXMC 2.0 is a Monte Carlo Simulation based program and makes it possible to predict effective dose and the probability of cancer development through entrance surface dose. Therefore, it is especially important to measure entrance surface dose through dosimeter. The purpose of this study is to measure entrance surface dose through semiconductor dosimeter, general dosimeter, glass dosimeter, and to compare and analyze the effective dose and probability of disease of critical organs. As an experimental method, the entrance surface dose of skull, chest, abdomen was measured per dosimeter and the effective dose and the probability of cancer development of critical organs per area was evaluated by PCXMC 2.0. As a result, the entrance surface dose per area was different in the order of a general dosimeter, a semiconductor dosimeter, and a glass dosimeter even under the same condition. Base on this analysis, the effective dose and probability of developing cancer of critical organs were also different in the order of a general dosimeter, a semiconductor dosimeter, and a glass dosimeter. In conclusion, it was found that the effective dose and the risk of diseases differ according to the dosimeter used, even under the same conditions, and through this study it was found that it is important to present an accurate entrance surface dose model according to each dosimeter.

• The Journal of the Korea Contents Association
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• v.12 no.6
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• pp.346-352
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• 2012

Radiation dose estimation on the newborn and infants during radiation examinations, unlike for the adults, is not actively being progressed. Therefore, as an index to present exposure dose during radiation examinations on newborn and infants, entrance skin dose was measured, and the result was compared with results of monte carlo simulation to raise reproducibility of entrance skin dose measurement, and it was proved that various geometry implementation was possible. The resulting values through monte carlo simulation was estimated using normalization factors for entrance skin dose to calibrate radiation dose and then normalized to a unit X ray radiation field size. Average entrance skin dose per one time exposure was $78.41{\mu}Gy$ and the percentage error between measurement by dosimeter and by monte carlo simulation was found to be -4.77%. Entrance skin dose assessment by monte carlo simulation provides possible alternative method in difficult entrance skin dose estimation for the newborn and infants who visit hospital for actual diagnosis.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.373-379
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• 2018

The purpose of this study was to investigate quantitative data on the difference in breast entrance surface dose with changes in focus-film distance, patient posture (anteroposterior-posteroanterior), thoracic wall thickness, rib bone thickness, lung tissue thickness, tube voltage, and high-voltage rectification method in Whole Spine Scanography, which is necessary for the treatment of scoliosis patients. Given a tube voltage of 90 kVp, kerma of 0.1 mGy, focus-film distance of 260 cm, tube voltage ripple rate of 0, filter thickness of 3.5 mm, and thickness of patient's thoracic wall of 120 mm as an X-ray exposure condition, from the simulation results using the Simulation of X-ray Spectra program to confirm the reduction effect of breast entrance surface dose according to the patient's posture (AP and PA), there was a dose reduction effect in aluminum filter thickness of 2.6 times at 3.5 mm, 25.7 times the thoracic wall thickness at 120 mm, 1.43 times higher tube voltage, and 0 to 1.14 times the tube voltage ripple rate. The total dose reduction effect was about 109 times. In order to confirm the dose reduction effect of RANDO phantom posture (AP and PA), from the results of the measurements taken under the conditions that the focus-film distance was 260 cm, the tube voltage was 90 kVp, the tube current was 270 mA, the exposure time was 0.31 sec, and the tube voltage ripple rate of X-ray generators was 0, the entrance surface dose reduction effect of the breast in the PA position was found to be 20.56 times lower than that of the AP position.

• Journal of radiological science and technology
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• v.36 no.2
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• pp.111-122
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• 2013

This study was carried out to reduce patient dose through focus-detector distance, kilovoltage, and a combination of copper filters. In the C, L-spine lateral, Skull AP views were obtained by making changes of 60-100 kV in tube voltage and of 100-200 cm in focus-detector distance and by adding a copper filter when using an auto exposure control device in the digital radiography equipment. The incident dose showed 90 kV, 0.3 mmCu in C-spine lateral with 0.06 mGy under the condition of 200 cm; 100 kV, 0.3 mmCu with 0.40 mGy under the condition of 200 cm and 90 kV 0.3 mmCu in Skull AP with the lowest value of 0.24 mGy under the condition of 140 cm. It was observed that entrance surface dose decreased the most when was increased by 150 cm, 70 kV (C-spine lateral), 81 kV (L-spine lateral). It was also found out that as the between the focus-detector increased in the expansion of the video decreased but the difference was not significant when the distance was 180 cm or more. Skull AP showed the most reduction in the entrance surface dose when the tube voltage was changed by 80 kV, 0.1 mmCu, and 120 cm. Therefore, when using the automatic exposure control device, it is recommended to use the highest tube voltage if possible and to increase focus-detector distance at least by 150~200 cm in wall and 120~140 cm in table in consideration of the radiotechnologist's physical conditions, and to combine 0.1~0.3 mmCu and higher filters. It is thus expected to reduce patient dose by avoiding distortion of images and reducing the entrance surface dose.

• Journal of radiological science and technology
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• v.39 no.3
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• pp.305-312
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• 2016

This study were compared with the direct measurement and indirect dose methods through various dose calculation in head and wrist. And, the modified equation was proposed considering equipment type, setting conditions, tube voltage, inherent filter, added filter and its accompanied back scatter factor. As a result, it decreased the error of the direct measurement than the existing dose calculation. Accordingly, diagnostic radiography patient dose comparison would become easier and radiogrphic exposure control and evaluation will become more efficient. The study findings are expected to be useful in patients' effective dose rate evaluation and dose reduction.

• Journal of the Korean Society of Radiology
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• v.5 no.6
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• pp.377-381
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• 2011

The purpose of this study is an assessment between the measured value of the nanoDot dosimeter and the calculated value of Non Dosimeter Dosimetry-Method(NDD-M) for entrance surface dose in general radiography. Measurement and calculation of the entrance surface doses were performed for head(AP), abdomen(AP), pelvis(AP), thoracic spine(AP) and lumbar spine(AP). As a result, the relative ratios of the measured value to the calculated value were acquired 1.5-2.1 for each region. Reproducibility acquired 0.035 as a coefficient of variation.

• Journal of the Korean Society of Radiology
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• v.10 no.5
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• pp.313-320
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• 2016

This research has been conducted to investigate the method of reducing patients' radiation exposure during X-ray imaging of Both Hip Ap examination by removing the grid. When using the grid with 60 kV and a non-filter, the Entrance Surface Dose was 4.77 mGy, and the result was highest and 34 times higher than the lowest measurement when removing the grid with 90 kV, and 0.3 mmCu filter. Based on the ICRP Pub. 60 at the level of 70 kV, the Effective Dose of testis and ovary was 0.255 mSv when using the grid, and that result was approximately 5.2 times higher than the 0.049 mSv when removing the grid. Based on the ICRP Pub. 103 at the level of 70 kV, the Effective Dose of testis and ovary was 0.090 mSv when using the grid, and that result was approximately 4.5 times higher than the 0.020 mSv when removing the grid. When using the grid, the range of Exposure Index was 671 to 782, and when removing the grid, the range of Exposure Index was 513 to 606, and both results were at optimal exposure conditions and valid diagnostic imaging after evaluations. Therefore, removing the grid during X-ray imaging of Both Hip Ap will help reduce patients radiation exposure.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.1001-1007
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• 2023

Dose limits are not applied to medical radiation exposure therefore justification and optimization should be essential for protecting radiation. This study explores methods to reduce exposure dose undergoing general radiation exam by bolus(tissue equivalent material) with keeping image quality. Hand PA projection with 50 kVp, 5 mAs, SID 100 cm, and 8×10 inch is referred by covered bolus of thickness 0, 3, 5, 8, and 10 mm for evaluation entrance dose and SNR. The entrance dose (μGy) to the hand by bolus thickness was 125.41±0.288, 106.85±0.255, 104.97±0.221, 91.68±0.299, and 90.94±0.106 showing a significant reduction in radiation exposure depending on if the bolus was used and bolus thickness. The SNR of the image was 13.997, 13.906, 12.240, 12.538, and 12.548 at each bolus thickness, showing no significant difference. It was confirmed that if appropriate thickness and size of bolus is used depending on the type of radiological imaging exam and the body site, a significant radiation dose reduction effect can be achieved without deteriorating image quality.

• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.179-186
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• 2004

A single-dosimeter worn on the anterior surface of body of a worker was found to provide significant underestimation of dose to the worker when radiation comes from behind of the human body. Recently, several researchers suggested that this kind of underestimation can be corrected to a certain extent by using an extra dosimeter on the back. But this multiple dosimetry also has the disadvantages like overestimation lowering work efficiency or cost burden. In this study, a single dosimeter introducing asymmetric filters enabled to identify PA exposure was designed by monte-carlo simulation and experiments and its dose evaluation algorithm for AP-PA mixed radiation field was established. This algorithm was applicable to penetrating radiation which had the effective energy more than 100 keV. Besides, the dosimeter and algorithm in this study were possible to be applied to near PA exposure.

• The Journal of the Korea Contents Association
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• v.19 no.8
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• pp.276-283
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• 2019

The purpose of this study is to evaluate the usefulness of automatic exposure control (AEC) by analyzing entrance surface dose (ESD) and entropy on using automatic exposure and manual exposure. The experimental method was to measure the dose by placing a semiconductor dosimeter on the Rando Phantom for the Pelvis, Abdomen, Skull, and Chest regions. The DICOM file was simultaneously acquired and then entropy was analyzed by using Matlab. As a result, when using the automatic exposure control, dose of all sites was lower than manual exposure's dose and entropy was high. In addition, paired t-test was performed for each item and p<0.05 was found in each item. In conclusion, the use of automatic exposure control can be a useful method to contribute to the optimization of the exposure dose and the image quality by reducing the amount of unnecessary radiation amount and information loss that can occur in X-ray examination.