• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.987-994
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• 2019

Low energy x-rays that occur in the low tube voltage radiography of general radiography are absorbed strongly in the body and do not aid image quality enhancement. This study maintains titer in general radiography while using tube current that are proportional to density and the tube voltage 15% principle according to density to reduce patient exposure doses, and area doses and entrance surface doses were measured to compare patient exposure doses. In hand, knee, abdomen, and skull radiography, kVp was increased to 115% and mAs was decreased to 50% and kVp was decreased to 85% while mAs was increased to 200% and area doses and entrance surface doses were measured to compare relative doses. Also, 5 places in each image were set, density was measured, and Kruskal wallis H test was conducted to observe significance probabilities between groups. To fix density, kVp was increased to 115% and mAs was decreased to 50% and after measurements of mean area doses and entrance surface doses were made by each part, each decreased to 58.68% and 59.85% when standard doses were set to 100%, and each increased to 147.28% and 159.9% when kVp was decreased to 85% and mAs was increased to 200%. Comparisons of density changes showed that hand, knee, abdomen, and skull radiography all displayed significance probabilities>0.05, showing no changes in concentration. Radiography that increases kVp and lowers mAs through reasonable calculations within ranges that don't affect resolution and contrast seems to be a simple way to decrease patient exposure doses.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.4
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• pp.177-183
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• 2011

This study intends to investigate patients' exact exposure doses by comparatively measuring ESD (Entrance Surface Dose) with the DAP meter, which excludes scattered rays, and ESD with the Xi multifunction meter, which includes scattered rays, by posture changes for Esophagography test and UGI test. The materialwere examined through Sonialvision-SafireII SPEC overtube system. ESD was measured by using the DAP meter, and as a tool to measure ESD including scattered rays on the plane of incidence of human phantom, the Xi multifunction meter was used. The average fluoroscopic time of Esophagography test was 4.192 minutes and the average number of images was 47.7, while the average fluoroscopic time of UGI test was 6.881 minutes and the average number of images was 37.8. The ratios of the incident dose of DAP meter and the ESD of Xi meter were calculated bydividing the fluoroscopic time and the number of images by each posture change. As for Esophagography test, the dose increased by 21.6~55.5% in the fluoroscopic test and by 4.8~24.7% in the spot test. In the front spot test, however, the does increased by as little as 5.3%. As for UGI test, the dose increased by 21.1~49.5% in the fluoroscopic test and by 10.1~34.9% in the spot test. It is expected that measuring doses in consideration of scattered rays by posture changes will be an important index in evaluating and managing patients' exact exposure doses for each test above. Furthermore, it is judged that this sort of study is inevitable and desirable to reduce patients' exposure doses after all.

• 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 Radiation Protection and Research
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• v.48 no.1
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• pp.15-19
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• 2023

Background: Cone beam computed tomography (CBCT) is a specialized medical equipment and plays a significant role in the diagnosis of oral and maxillofacial diseases and abnormalities; however, it is attributed to risk of exposure of ionizing radiation. The aim of the study was to estimate and determine the amount of scattered radiation dose to the thyroid gland in dental CBCT during maxilla and mandible scan. Materials and Methods: The average scattered radiation dose for i-CAT 17-19 Platinum CBCT (Imaging Sciences International) was measured using a Multi-O-Meter (Unfors Instruments), placed at the patient's neck on the skin surface of the thyroid cartilage, with an exposure parameter of 120 kVp and 37.07 mAs. The surface entrance dose was noted using the Multi-O-Meter, which was placed at the time of the scan at the level of the thyroid gland on the anterior surface of the neck. Results and Discussion: The surface entrance dose to the thyroid from both jaws scans was 191.491±78.486 µGy for 0.25 mm voxel and 26.9 seconds, and 153.670±74.041 µGy from the mandible scan, whereas from the maxilla scan the surface entrance dose was 5.259±10.691 µGy. Conclusion: The surface entrance doses to the thyroid gland from imaging of both the jaws, and also from imaging of the maxilla and mandible alone were within the threshold limit. The surface entrance dose and effective dose in CBCT were dependent on the exposure parameters (kVp and mAs), scan length, and field of view. To further reduce the radiation dose, care should be taken in selecting an appropriate protocol as well as the provision of providing shielding to the thyroid gland.

• Korean Journal of Digital Imaging in Medicine
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• v.11 no.1
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• pp.15-20
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• 2009

Far reducing medical radiation exposure and managing patient doses, Entrance surface doses(ESDs) were measured at Diagnostic Radiology Department in ASAN medical center, also we determined and compared with the Diagnostic Reference Level(DRL) of some other countries. ESDs were measured far the most common types of X-ray procedures, such as chest PA, lumbar spine AP, lumbar spine lateral, Pelvis AP, Skull PA. ESDs were measured by Glass dosimeter and Unfors Xi meter. Those were applied collimation center of phantom's entrance skin surface. The results of ESDs were compared Glass dosimeter with Unfors Xi meter. Those were measured within 5% statistical difference. It seemed well agreement at two devices. In most cases ESDs measured far the different types of X ray procedures were found to be lower than the DRL of IAEA, but ESDs on chest PA, lumbar spine AP, lumbar spine lateral, Pelvis AP, Skull PA were proximity ar excesses at DRL of advanced country. Through this study, we need an investigation and improvement at present diagnostic radiology exam system. Also, radiologists make an effort to reduce patient dose and having a technical skill.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.45-51
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• 2022

This study compared DLP values along with phantom entrance surface doses and the image quality of chest CT scans made using a Care Dose 4D+Care kV System, scans that are made using only the Care Dose 4D function, and scans that are made with changes made by applying 80 kVp, 100 kVp, 120 kVp, and 140 kVp to the Care Dose 4D and tube voltage to search for methods to maintain the highest image quality with minimal patient doses. It was shown that DLP values decreased 6.727% when scans were taken with Chest Care Dose 4D + Care kV semi 100 and 6.481% when scans were taken with Chest Care Dose 4D + Care kV. With Chest Non as a standard, skin surface doses decreased 16.519% when scans were taken with Chest Care Dose 4D + Care kV semi 100 and 15.705% when scans were taken with Chest Care Dose 4D + Care kV. With comparisons of image quality, when comparisons were made with Chest Non, comparisons made of SNR values and CNR values in all scanning conditions including Care Dose 4D + Care kV showed that there were no significant differences at P>0.05. Imaging using Chest Care Dose 4D + Care kV in chest CT showed that exposure doses decreased similarly to result values gained from the best conditions through manual adjustments of kV and mAS, and there were no significant differences in image SNR and CNR. If the Chest Care Dose 4D + Care kV function is used, image quality is maintained and patient exposure to radiation can be reduced.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.39-46
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• 2012

Purpose : The purpose of this study was to reduce Entrance Surface Dose and maintain image quality by changing Source to Image receptor Distance. And we'd like to compare ESD on this study to DRLs in other contries. Materials and Methods : We used indirect DR system(Definium 8000, General Electric, USA)and phantom(ART-200X, Flukebiomedical, USA),glass dosimeters(GD-352M, Asahi Techno Glass, Japan)for this study. The imagies were obtained throuh 80kVp fixed, and different tube currents using AEC mode in $16{\times}16$(inch) field size and changing Source to Image receptor Distance from 100 cm to 130 cm per 10 cm unit. The phantom with attaching 5 glass dosimeters on abdomonal skin was set at supine and erect position as a anterioposterial projection on detector For measuring Entrance Surface Dose. Image analysis was conducted by histograms of Image J(1.46r) which was given from National Institutes of Health(NIH). Results : Due to inverse square law of distance, the tube currents were increasing 42.6 % in supine position and 32.6 % in erect position according to the change of Source to Image receptor Distance. While Entrance Surface Doses were rapidly decreasing 14.2 % in supine position and 29.4 % in erect position according to the change of Source to Image receptor Distance. As the results of histogram using Image J, pixel mean values from 100 cm to 110 cm, 120 cm and 130 cm were decreasing each 1.4%, 2.5%, 2.7%, 4.5%, 2.2 %, 5.8 % in supine, erect position. While standard deviations from 100 cm to 110 cm, 120 cm and 130 cm were increasing each 1.4 %, 2.5 %, 2.5 %, 4.0 %, 2.0 %, 4.9 % Consequently, there are no significant differences in abdomen images taken. Conclusion: As the results described above, we strongly recommend using long Sourceto Image receptor Distance than 100cm that we have been using. So, we should deliver less Entrance Surface Dose to the patients while maintaining image quality in abdomen radiography.

• Journal of the Korean Physical Society
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• v.73 no.9
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• pp.1377-1384
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• 2018

Accurate measurement of the absorbed dose and the effective dose is required in dental panoramic radiography involving relatively low energy with a rotational X-ray tube system using long exposures. To determine the effectiveness of measuring the irradiation by using passive dosimetry, we compared the entrance skin doses by using a radiophotoluminescent glass dosimeter (RPL) and an optically stimulated luminescence detector (OSL) in a phantom model consisting of nine and 31 transverse sections. The parameters of the panoramic device were set to 80 kV, 4 mA, and 12 s in the standard program mode. The X-ray spectrum was applied in the same manner as the panoramic dose by using the SpekCalc Software. The results indicated a mass attenuation coefficient of $0.008226cm^2/g$, and an effective energy of 34 keV. The equivalent dose between the RPL and the OSL was calculated based on a product of the absorbed doses. The density of the aluminum attenuators was $2.699g/cm^3$. During the panoramic examination, tissue absorption doses with regard to the RPL were a surface dose of $75.33{\mu}Gy$ and a depth dose of $71.77{\mu}Gy$, those with regard to the OSL were surface dose of $9.2{\mu}Gy$ a depth dose of $70.39{\mu}Gy$ and a mean dose of $74.79{\mu}Gy$. The effective dose based on the International Commission on Radiological Protection Publication 103 tissue weighting factor for the RPL were $0.742{\mu}Sv$, $8.9{\mu}Sv$, $2.96{\mu}Sv$ and those for the OSL were $0.754{\mu}Sv$, $9.05{\mu}Sv$, and $3.018{\mu}Sv$ in the parotid and sublingual glands, orbit, and thyroid gland, respectively. The RPL was more effective than the OSL for measuring the absorbed radiation dose in low-energy systems with a rotational X-ray tube.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.535-541
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• 2016

This study aimed to identify dose reduction measures by retrospectively analyzing the entrance surface dose at computed tomography and angiography in cardiovascular examination and to contribute the patients with renal impairmend and a high probability of side effects to determine the inspection's direction by measuring the contrast usages actually to active actions for the dose by actually measuring the contrast medium dose. The CTDIvol value and air kerma value, which are the entrance surface doses of the two examinations, and the contrast medium dose depending on the number of slides were compared and analyzed. This study was conducted in 21 subjects (11 males; 10 females) who underwent Cardiac Computed Tomographic Angiography (CCTA) and Coronary Angiography (CAG) in this hospital during the period from May 2014 to May 2016. The subject's age was 48~85 years old (mean $65{\pm}10$ years old), and the weight was 37.6~83.3 kg (mean $63{\pm}6kg$). Dose reduction could be expected in the cardiovascular examination using CCTA rather than in the examination using CAG. In terms of contrast medium dose, CAG used a smaller dose than CCTA. In particular, as the number of slides increases at CAG, the contrast medium dose increases. Therefore, in order to reduce the contrast medium dose, the number of slides suitable for the scan range must be selected.

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