• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.288-294
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• 2013

Chest digital tomosynthesis was the most advanced digital radiography technology, but it was higher patient dose than conventional chest radiography. Thus we tried to reduce a patient dose of chest digital tomosynthesis and evaluated its image quality. Result shows that radiation dose such as ESD, DAP and ED were 1.95 mGy, 17.66 $dGycm^2$ and 0.133 mSv respectively in default setting and 0.312 mGy, 2.27 $dGy.cm^2$ and 0.052 mSv in use additional filter, respectively. Doses were decrease 66.2%, 73.6% and 57.4% in ESD, DAP and ED, respectively. At the image quality assessment, overall sensitivities of use additional filter for nodule detection were not inferior to default mode for peripheral, central and peripheral micro nodules. However, sensitivity of low dose mode was significantly inferior to the default for central micro-nodules(p < .001).

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.1
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• pp.32-36
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• 2016

Purpose In nuclear medicine examination, $^{131}I$ is widely used in nuclear medicine examination such as diagnosis, treatment, and others of thyroid cancer and other diseases. $^{131}I$ conducts examination and treatment through emission of ${\gamma}$ ray and ${\beta}^-$ ray. Since $^{131}I$ (364 keV) contains more energy compared to $^{99m}Tc$ (140 keV) although it displays high integrated rate and enables quick discharge through kidney, the objective of this study lies in comparing the difference in exposure dose of $^{131}I$ before and after wearing apron when handling $^{131}I$ with focus on 3 elements of external exposure protection that are distance, time, and shield in order to reduce the exposure to technicians in comparison with $^{99m}Tc$ during the handling and administration process. When wearing apron (in general, Pb 0.5 mm), $^{99m}Tc$ presents shield of over 90% but shielding effect of $^{131}I$ is relatively low as it is of high energy and there may be even more exposure due to influence of scattered ray (secondary) and bremsstrahlung in case of high dose. However, there is no special report or guideline for low dose (74 MBq) high energy thus quantitative analysis on exposure dose of technicians will be conducted based on apron wearing during the handling of $^{131}I$. Materials and Methods With patients who visited Department of Nuclear Medicine of our hospital for low dose $^{131}I$ administration for thyroid cancer and diagnosis for 7 months from Jun 2014 to Dec 2014 as its subject, total 6 pieces of TLD was attached to interior and exterior of apron placed on thyroid, chest, and testicle from preparation to administration. Then, radiation exposure dose from $^{131}I$ examination to administration was measured. Total procedure time was set as within 5 min per person including 3 min of explanation, 1 min of distribution, and 1 min of administration. In regards to TLD location selection, chest at which exposure dose is generally measured and thyroid and testicle with high sensitivity were selected. For preparation, 74 MBq of $^{131}I$ shall be distributed with the use of $2m{\ell}$ syringe and then it shall be distributed after making it into dose of $2m{\ell}$ though dilution with normal saline. When distributing $^{131}I$ and administering it to the patient, $100m{\ell}$ of water shall be put into a cup, distributed $^{131}I$ shall be diluted, and then oral administration to patients shall be conducted with the distance of 1m from the patient. The process of withdrawing $2m{\ell}$ syringe and cup used for oral administration was conducted while wearing apron and TLD. Apron and TLD were stored at storage room without influence of radiation exposure and the exposure dose was measured with request to Seoul Radiology Services. Results With the result of monthly accumulated exposure dose of TLD worn inside and outside of apron placed on thyroid, chest, and testicle during low dose $^{131}I$ examination during the research period divided by number of people, statistics processing was conducted with Wilcoxon Signed Rank Test using SPSS Version. 12.0K. As a result, it was revealed that there was no significant difference since all of thyroid (p = 0.345), chest (p = 0.686), and testicle (p = 0.715) were presented to be p > 0.05. Also, when converting the change in total exposure dose during research period into percentage, it was revealed to be -23.5%, -8.3%, and 19.0% for thyroid, chest, and testicle respectively. Conclusion As a result of conducting Wilcoxon Signed Rank Test, it was revealed that there is no statistically significant difference (p > 0.05). Also, in case of calculating shielding rate with accumulate exposure dose during 7 months, it was revealed that there is irregular change in exposure dose for inside and outside of apron. Although the degree of change seems to be high when it is expressed in percentage, it cannot be considered a big change since the unit of accumulated exposure dose is in decimal points. Therefore, regardless of wearing apron during high energy low dose $^{131}I$ administration, placing certain distance and terminating the administration as soon as possible would be of great assistance in reducing the exposure dose. Although this study restricted $^{131}I$ administration time to be within 5 min per person and distance for oral administration to be 1m, there was a shortcoming to acquire accurate result as there was insufficient number of N for statistics and it could be processed only through non-parametric method. Also, exposure dose per person during lose dose $^{131}I$ administration was measured with accumulated exposure dose using TLD rather than through direct-reading exposure dose thus more accurate result could be acquired when measurement is conducted using electronic dosimeter and pocket dosimeter.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.619-625
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• 2022

In the field of imaging medicine, computed tomography is one of the most common test methods and one of the most frequently used test methods in hospitals. However, it is accompanied by a very high radiation exposure compared to other test methods. In order to reduce exposure, CT scans should be performed only when absolutely necessary, and even if the tests are performed because they are absolutely necessary, a protocol that serves the purpose of the test and allows the test to be performed in a small dose should be used. In this study, we wanted to learn about the most up-to-date radiation dose usage information used by the region's leading general hospitals and develop a diagnostic reference level (DRL). In the experimental results, the Head CT and Abdomen CT tests showed that DLP was higher than the NRPB (U.K) and Korean DRL. The DLP values used by Chest CT were low for all 3 types of CT devices. The hospital found that efforts to reduce exposure should be made during CT examinations, and in particular, Head CT and Abdomen CT determined that efforts to reduce exposure were necessary.

• Journal of the Korean Society of Radiology
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• v.17 no.4
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• pp.551-556
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• 2023

Angiography equipment is used to evaluate and treat coronary artery disease. As a common feature of equipment, radiation is used, and function development for dose reduction is being carried out by each company. Therefore, the difference depending on whether DCR installed in angiography equipment is used is analyzed from a radiological point of view to prove the effect. Among 431 patients who underwent coronary artery intervention from March 2021 to February 2023, 250 patients with retrospective data were selected. And than among the 250 subjects obtained, 91 patients used the cardiovascular roadmap function during single-vessel intervention, and 159 patients did not use the roadmap. When DCR was used, total dose area product (34.57 uGy/m² : 69.15 uGy/m²), total air kerma dose (688.47 mGy : 1640.4 mGy), fluoroscopy dose (23.87 uGy/m² : 49.91 uGy/m²) and fluoroscopy time (723.55 s : 366.03 s), total number of images (17 : 26) showed lower values and were statistically significant than those not used. The use of DCR function in single vessel coronary intervention is thought to be radiologically safer as single vessel coronary intervention using dynamic cardiovascular DCR showed lower perspective time and perspective dose than procedures performed without the DCR.

• Journal of the Korean Society of Radiology
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• v.14 no.3
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• pp.253-259
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• 2020

Mammography has the advantage of being economical, simple and effective in detecting microcalcification, but breast is a highly sensitive organ and is accompanied by the risk of an over-exposure. While accurate dose assessments are important to prevent this, current breast dose assessments are limited to breast implant patients. This purpose of this study was to identify dose variations due to tube voltages by forming a mock-up with breast implants for an accurate dosimetric assessment on breast implant patients. As a result, doses from the presence of breast implants were smaller than those from the absence of the mammal. As the result of the change of the voltage to 26, 28, 30, and 32 kV, the imcreased tube voltage included larger dose regardless of the presence of Breast implant. Therefore, it is believed that diagnosis recommendations for breast implants will be possible if further studies on internal and external bioretical imaging and quality assessment are carried out as the basis for this study.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.23-30
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• 2015

Positron emission tomography scan has been growing diagnostic equipment in the development of medical imaging system. Compare to 99mTc emitting 140 keV, Positron emission radionuclide emits 511 keV gamma rays. Because of this high energy, it needs to reduce radioactive emitting from patients for radio technologist. We searched the external dose rates by changing distance from patients and measure the external dose rates when we used shielder investigate change external dose rates. In this study, the external dose distribution were analyzed in order to help managing radiation protection of radio technologists. Ten patients were searched (mean age: $47.7{\pm}6.6$, mean height: $165.5{\pm}3.8cm$, mean weight: $65.9{\pm}1.4kg$). Radiation was measured on the location of head, chest, abdomen, knees and toes at the distance of 10, 50, 100, 150, and 200 cm, respectively. Then, all the procedure was given with a portable radiation shielding on the location of head, chest, and abdomen at the distance of 100, 150, and 200 cm and transmittance was calculated. In 10 cm, head ($105.40{\mu}Sv/h$) was the highest and foot($15.85{\mu}Sv/h$) was the lowest. In 200 cm, head, chest, and abdomen showed similar. On head, the measured dose rates were $9.56{\mu}Sv/h$, $5.23{\mu}Sv/h$, and $3.40{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.24{\mu}Sv/h$, $1.67{\mu}Sv/h$, and $1.27{\mu}Sv/h$ in 100, 150, and 200 cm on head. On chest, the measured dose rates were $8.54{\mu}Sv/h$, $4.90{\mu}Sv/h$, $3.44{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.27{\mu}Sv/h$, $1.34{\mu}Sv/h$, and $1.13{\mu}Sv/h$ in 100, 150, and 200 cm on chest. On abdomen, the measured dose rates were $9.83{\mu}Sv/h$, $5.15{\mu}Sv/h$, and $3.18{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.60{\mu}Sv/h$, $1.75{\mu}Sv/h$, and $1.23{\mu}Sv/h$ in 100, 150, and 200 cm on abdomen. Transmittance was increased as the distance was expanded. As the distance was further, the radiation dose were reduced. When using shielder, the dose were reduced as one-forth of without shielder. The Radio technologists are exposed of radioactivity and there were limitations on reducing the distance with Therefore, the proper shielding will be able to decrease radiation dose to the technologists.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.353-358
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• 2014

This study was conducted to analyze the patient's exposed dose targeting the patients who had acute ischemic stroke symptoms and CT brain perfusion scan, by comparing fixed time technique and bolus tracking technique which was provided by the manufacturer and to identify the Time graph to implement the usability of contrast medium's tracking technique the best contrast enhancement intervals. $CTDI_{VOL}$ of PCT in patient appeared to be 431.72mGy in fixed scan delay protocol, whereas 323.61mGy in Bolus tracking technique. The value of DLP appeared to be $1243.47mGy{\cdot}cm$ in fixed scan delay protocol, whereas $932mGy{\cdot}cm$ in Bolus tracking technique. Time graph appeared to be various in fixed scan delay protocol, whereas the optimal time graph could be obtained in Bolus tracking. The exposure dose could be reduced by 25% applying Bolus tracking technique when taking brain perfusion CT scan.

• Proceedings of the Korea Contents Association Conference
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• 2011.05a
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• pp.191-192
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• 2011

X선 촬영을 통한 집단 건강검진은 경제성, 신속성, 대량처리 능력을 충족시키고 있으며 찾아가는 이동 의료서비스에서 중요한 부분을 차지하고 있다. 이와 함께 X선 촬영을 통한 집단 건강검진 시스템도 발전하여 간접촬영방식에서 Digital Radiography를 이용한 직접촬영방식으로 기술력이 향상되었고 이로써 검진차량에서 검진을 받는 환자나 종사자들에 대한 피폭선량의 증가하고 있으나 차량 외부의 누설방사선량에 대한 조사는 아직도 미미하다 할 수 있다[1]. 이에 본 연구에서 실험을 통한 결과는 다음과 같이 나타났다. 누설방사설량이 가장 많이 발생하는 곳은 출입문과 후면(검출기)에서는 우측, 양측면에서는 중앙이 가장 많은 누설방사선량이 나타났고, 측정위치별로는 검출기가 인접한 후면에서 누설방사선량이 가장 높았다. 기준치에 크게 벗어나지는 않았지만 누설방사선량은 다양하게 나타났다. 특히 후면에서의 누설방사선량은 기준치를 크게 웃돌아 방사선 차폐시설이 잘 갖추어지지 않은 것을 알 수 있으며 향후 이동검진차량의 방사선 차폐시설을 갖추는데 있어 각별한 관심이 필요하리라 사료된다.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.535-540
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• 2015

Collimator has important functions with control primary X-ray that decrease radiation exposure dose for patients and reduce scatter ray and make better quality of image. But there are no regulations for X-ray mammography device of collimator, so widely used device adopt rectangularly controlled collimator. Though digital X-ray mammography device expand supply recently, rectangularly controlled collimator of film/screen mode still used. After searching for real condition of beam field with digital mammography, we made a multi-leaf collimator which is able to adjust the beam field in accordance with size and shape of breast, and we measuring up the transitions of image quality, average glandular dose(AGD) and, Dose area product(DAP). There are no significant differences between rectangularly controlled collimator and multi-leaf collimator, and DAP value decreased by 50.72%. As conclusion, there needs to expand the use of multi-leaf collimator for optimum adoption of beam field in digital mammography, and also need to develop an automatic regulation of beam field for reduce of exposure dose to patients.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.367-373
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• 2020

Most of the spatial scattered dose caused by the scattered rays generated by the collision between the object and X-rays is relatively easily absorbed by the human body as electromagnetic waves in the low energy region, thereby increasing the degree of radiation exposure. Such spatial scattering dose is also used as an indicator of the degree of radiation exposure of radiation workers and patients, and there is a need for a method to reduce exposure by reducing the spatial scattered dose that occurs indirectly. Therefore, in this study, a lead-free radiation shielding sheet was proposed as a way to reduce the spatial scattering dose, and a Monte Carlo (MC) simulation was performed based on a chest X-ray examination. The absorbed dose was calculated and the measured value and the shielding rate were compared and evaluated.