• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3347-3352
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• 2010

It is recommended that the door of control room is closed during radiography to protect a radiologic technologist. However, for those patients such as of emergency or pediatrics, the door must be kept open unavoidably to apply immediate medical administration and treatment on the potential case of emergency which could be happened through the course of radiography. In addition, it could be efficient by reducing patients waiting time when the door is open for a general case. This study was conducted to evaluate practical exposure rate to a radiologic technologist when the door is open during the radiography, and to find out the ways to minimize radiation exposure and to increase the efficiency simultaneously. Measuring practical exposure rate was fulfilled with glass dosimeter, and it was 2.02 mGy/week at the location of radiologic technologist under the condition that the door is open during the radiography, which was about 2.3 times higher than the 100 mR/week. It means that the considerable amount of scattered rays through the door opening, and increase exposure rate at the radiologic technologist. Hence we confirmed that a radiologic technologist probably overexposed if the door is open during the radiography. It was also confirmed by the Monte Carlo simulation that the exposure rate could be reduced up to approximately 1/100 by change only the door opening direction. In conclusion, since the proper door opening direction provides same shielding effect whether it is open or close, the door opening direction need to be considered when it is installed at radiography facilities.

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

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.819-825
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• 2024

The reason for recording dose data when using a diagnostic radiation source is to record and manage the dose to healthcare personnel and patients. The purpose of this study was to verify the difference in radiation dose when using diagnostic radiation generating devices and to inform users' awareness of dose reduction through measurement and analysis of dose in situations with and without shielding. The dose analysis of each equipment for two Korean C-arms and two German C-arms showed that the Korean FPD type C-arm had the highest dose value, followed by the German I.I type C-arm, German FPD type C-arm, Korean, and I.I type C-arm. The results of the dose analysis with and without shielding showed that the dose to the human phantom in a normal atmosphere increased by about 2 times due to scattered radiation, but the dose to the human phantom was reduced by about 5 times by wearing a shield (0.5mm/lead apron). More important than the management of radiation dose is the study of how to reduce exposure when using radiation, and since the radiation dose output from different equipment is different, it is necessary to provide dose information with and without shielding.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.871-877
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• 2022

This study was conducted to improve the problems of exposure dose and image reading applied to patients due to the incorrect use of AEC during chest radiography. Images were acquired by dividing the case where AEC was used as the test condition and the case where AEC was not used. As a result of the study, the dose was reduced by 1.17% in 110 kVp without AEC than with AEC, 17.2% decrease at 100 kVp, 30.19% decrease at 90 kVp, and 46.45% decrease at 80 kVp. There was a significant difference in the statistical values according to the tube voltage change in the lung, trachea, and heart SNR average values with AEC and without AEC 110 kVp, but the difference in image quality was insignificant in actual images. When AEC was not applied at the same tube voltage, the dose could be reduced by 17.2% while maintaining the image quality similar to that of with AEC at 100 kVp without AEC. Therefore, rather than relying on AE conditions during chest radiographic examination, it is considered that the conditions should be considered for the examination while lowering the dose by selecting an appropriate tube voltage.

• Radiation Oncology Journal
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• v.19 no.4
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• pp.319-326
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• 2001

Purpose : Planning target volume (PTV) for tumors in abdomen or thorax includes enough margin for breathing-related movement of tumor volumes during treatment. Depending on the location of the tumor, the magnitude of PTV margin extends from 10 mm to 30 mm, which increases substantial volume of the irradiated normal tissue hence, resulting in increase of normal tissue complication probability (NTCP). We developed a simple and handy method which can reduce PTV margins in patients with liver tumors, respiratory motion reduction device (RRD). Materials and methods : For 10 liver cancer patients, the data of internal organ motion were obtained by examining the diaphragm motion under fluoroscope. It was tested for both supine and prone position. A RRD was made using MeV-Green and Styrofoam panels and then applied to the patients. By analyzing the diaphragm movement from patients with RRD, the magnitude of PTV margin was determined and dose volume histogram (DVH) was computed using AcQ-Plan, a treatment planning software. Dose to normal tissue between patients with RRD and without RRD was analyzed by comparing the fraction of the normal liver receiving to $50\%$ of the isocenter dose. DVH and NTCP for normal liver and adjacent organs were also evaluated. Results : When patients breathed freely, average movement of diaphragm was $12{\pm}1.9\;mm$ in prone position in contrast to $16{\pm}1.9\;mm$ in supine position. In prone position, difference in diaphragm movement with and without RRD was $3{\pm}0.9\;mm$ and 12 mm, respectively, showing that PTV margins could be reduced to as much as 9 mm. With RRD, volume of the irradiated normal liver reduced up to $22.7\%$ in DVH analysis. Conclusion : Internal organ motion due to breathing can be reduced using RRD, which is simple and easy to use in clinical setting. It can reduce the organ motion-related PTV margin, thereby decrease volume of the irradiated normal tissue.

• Progress in Medical Physics
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• v.13 no.2
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• pp.62-68
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• 2002

A muiltileaf collimator (MLC) is used as a replacement for conventional blocks. The MLC, however may not be appropriate for a fine field shaping. For the fine field shaping, conventional block can be added under the MLC. But it may significantly affect on the dosimetric characteristics such as surface dose of skin, buildup region and percent depth doses. We performed the study to evaluate the surface dose and the maximum depth dose using MLC conjunction with conventional blocks for various field sizes and energies. We confirmed the surface dose was increased by using the additional conventional block under the MLC ranging from 10 to 35.6％ according to various field sizes and radiation beam energies. The surface dose was effectively reduced by application of 2 or 3 m thickness of lead plate as electron filter.

• Journal of the Korean Society of Radiology
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• v.1 no.3
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• pp.23-34
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• 2007

To find how much radiation was exposed the patients who visit emergency room, a measurement study was made for radiation amount toward 200 patients selected randomly among visitors to an emergency room in a university hospital from March 16 to 31st, 2006. The results are as follows ; 1. Among the subjects 50 person(25.0%) were transferred from other hospitals, 24 persons(8.3) come after traffic accident, 50 persons for other accident and 76 persons for general medical care. 2. The average frequency of X-ray taking was calculated as 6.4 time per person among transferred patients, 14.5 times per person among patients with traffic accident and 2.6 times per person among general medical care. 3. The radiation exposure amount by kind of X-ray showed 28.9mGyfor general X-ray diagnosis, 84.2mGy for CT scanning and 1.02mGy for other special radiation study. 4. Average radiation exposure amount was calculated as 24.6mGy by transferred patients, 55.2mGy by patients with traffic accident, 17.1mGy by patients with other accidents and 17.0mGy by general patients. 5. Through the comparison of radiation exposure amount among to subject with maximum allowance threshold by International Commission on X-ray Radium Protection, transferred patients exceeded 6 times than allowance in whole body except extremities and joints, blood forming organ, reproductive system, vitreous body of eye, bone, thyroid gland, skin and etc, Patient suffered from traffic accidents were exposed 10 times more than allowance. In conclusion, the radiation exposure amount during X-rat diagnosis re too much and exceeded allowance standard by International Commission on X-ray Radium Protection. So further study and preventive measure to decrease radiation exposure by patients who visit emergency room.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.51-57
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• 2014

Purpose : In the case of treating pancreatic cancer, the importance is put on the spread of dose. Changes take place in duodenum in accordance with respiration. Thus, in this paper, I am going to trace the positioning of duodenum and the changes in bulks of body per dose by scanning the patients' Kilovoltage Cone-Beam CT using the hospital equipped CT-on rail System. Materials and Methods : Seeing three patients, I have acquired KVCBCT by using CT-on rail System and spotted the change in positioning at duodenum after comparing with the preliminary image of treatment plan by using SYNGO Software. Then, I followed the change in the bulk of duodenum and analyzed the changes in bulks of body on the same dose by transmitting the acquired KVCBCT into Pinnacle, a treatment plan system. Results : The changes in the positioning shall be as set forth like this: 1.2cm, 1.0cm in Left-Right Direction, 0cm, 0.8cm in Craniocaudal Direction, 0.1cm, and 1.0cm in Anterior-Posterior Direction. Patient number one showed that his bulks in body had increased by maximum 460%, minimum 120%, the bulks in patient number two had increased bymaximum 490%, minimum 160%, and the bulks of patient number three had increased by maximum 150%. But Minimum volume decreased 30%. Patient number one showed only a little bit of change at first when compared with the preliminary treatment plan. However, the dose increased the bulks in the patient's body: $V_{10}$ 118%, $V_{20}$ 117%, $V_{30}$ 400%, and $V_{40}$ 480% Conclusion : In treating patients with radiation therapy using 3D-CRT, the dose amount penetrated into duodenum needs to be minimized by planning appropriate treatment beforehand. In order to establish an appropriate treatment plan it is required to comprehend the changes at positioning of the duodenum by respiration and predict the changes in the bulks of duodenum by setting precise Planning Target Volume.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.655-661
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• 2017

Sparse view CT has been widely used to reduce radiation dose to patient in radiation therapy. In this work, we performed sinogram restoration from sparse sampling data by using inpainting method for simulation and experiment. Sinogram restoration was performed in accordance with sampling angle and restoration method, and their results were validated with root mean square error (RMSE) and image profiles. Simulation and experiment are designed to fan beam scan for various projection angles. Sparse data in sinogram were restored by using linear interpolation and inpainting method. Then, the restored sinogram was reconstructed with filtered backprojection (FBP) algorithm. The results showed that RMSE and image profiles were depended on the projection angles and restoration method. Based on the simulation and experiment, we found that inpainting method could be improved for sinogram restoration in comparison to linear interpolation method for estimating RMSE and image profiles.

• Journal of radiological science and technology
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• v.39 no.1
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• pp.1-11
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• 2016

The purpose of this study was to provide resources for medical exposure reduction through evaluation of organ dose and image resolution for lumbar spine around according to the size of the collimator in DR system. The size of the collimator were varied from $8^{\prime\prime}{\times}17^{\prime\prime}$ to $14^{\prime\prime}{\times}17^{\prime\prime}$ by 1" in AP and lateral projection for the lumbar spine radiography with RANDO phantom. The organ dose measured for liver, stomach, pancreas, kidney and gonad by the glass dosimeter. The image resolution was analyzed using the Image J program. The organ dose of around lumbar spine were reduced as the size of the collimator is decreased in AP projection. There were no significant changes decreasing rate whenever the size of the collimator were reduced 1" in the gonad. The organ dose showed higher on liver and kidney near the surface in lateral projection. There were decreasing rate of less than 5% in liver and kidney, but decreasing rate was 24.34% in the gonad whenever the size of the collimator were reduced 1". Organ dose difference for internal and external of collimator measured $549.8{\mu}Gy$ in the liver and $264.6{\mu}Gy$ in the stomach. There were no significant changes organ dose difference that measured $1,135.1{\mu}Gy$ in the gonad. Image Quality made no difference because SNR and PSNR were over than 30 dB when the collimator size is less than $9^{\prime\prime}{\times}17^{\prime\prime}$ on AP projection and $10^{\prime\prime}{\times}17^{\prime\prime}$ on lateral projection. Therefore, we are considered that the recommendations criterion for control of collimator were suggested in order to reduce unnecessary X-ray exposure and to obtain good image quality because lumbar spine radiography contains a lot of peripheral organs rather than other area radiography.