• Restorative Dentistry and Endodontics
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• v.37 no.3
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• pp.160-164
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• 2012

Objectives: This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Materials and Methods: Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. Results: The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. Conclusions: When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.

• Journal of radiological science and technology
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• v.39 no.3
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• pp.323-328
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• 2016

The spatial dose distribution was measured with ionization chamber as preliminary study to evaluate operator dose and to study dose reduction during neuro-interventional procedures. The zone of operators was divided into four area (45, 135, 225, and 315 degree).We supposed that operator exist on the four area and indicated location of critical organs(eyes, breast, gonad). The spatial doses were measured depending on distance( 80, 100, 120, and 140 cm) and location of critical organs. The spatial doses of area of 225 degree were 114.5 mR/h (eyes location), 143.1 mR/h (breast location) and 147 mR/h (gonad location) in 80 cm. When changed location of x-ray generator, spatial dose increased in $18.1{\pm}10.5%$, averagely. We certified spatial dose in the operator locations, Using the results of this study, It is feasible to protect operator from radiation in neuro-interventional procedures.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.493-499
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• 2016

In this study, C-Arm equipment is being used as we intend to verify the exposure dose on the operator by the scattering rays during the operation of the C-Arm equipment and to provide an effective method of reducing the exposure dose. Exposure dose is less than the Over Tube method utilizes the C-arm equipment Under Tube the scheme, The result showed that the exposure dose on the operator decreased with a thicker shield, and as the operator moved away from the center line. Moreover, as the research time prolongated, the exposure dose increased, and among the three affixed location of the dosimeter, the most exposure dose was measured at gonadal, then followed by chest and thyroid. However, in consideration of the relationship between the operator and the patient, the distance cannot be increased infinitely and the research time cannot be decreased infinitely in order to reduce the exposure dose. Therefore, by changing the thickness of the radiation shield, the exposure dose on the operator was able to be reduced. If you are using a C-Arm equipment discomfort during surgery because the grounds that the procedure is neglected and close to the dose of radiation shielding made can only increase. Because a separate control room cannot be used for the C-Arm equipment due to its characteristic, the exposure dose on the operator needs to be reduced by reinforcing the shield through an appropriate thickness of radiation shield devices, such as apron, etc. during a treatment.

• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.2085-2091
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• 2020

The license for Kori-1, the first commercial reactor in Busan, Korea, was terminated in June 2017; therefore, preparations are being made for its decommissioning. Because the radioactivity of Bio-shield varies greatly throughout the structure, the doses received by the workers depend on the location, order, and duration of dismantling operations. Thus, a model for evaluating the worker external dose during the dismantling of the Kori-1 bio-shield was developed, and work scenarios for dose assessment were designed. The Dose evaluation code VISIPLAN was used for dose assessment. The dose rate around the bio-shield was evaluated and the level of exposure to the operator was evaluated according to the work scenario. The maximum annual external dose was calculated as 746.86 mSv for a diamond wire saw operator under dry cutting conditions, indicating that appropriate protective measures, such as changing dismantling sequence, remote monitoring, shield installation, and adjustment of work team are necessary for the safe dismantling of the bio-shield. Through these protective measures, it was found that the worker's dose could be below the dose limit.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.579-587
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• 2017

Although interventional procedures use very low tube currents, there is a high risk of exposure to radiation as well as the operator due to long-term radiation exposure. The purpose of this study is to investigate the effects of radiation dose on the quality of the operator by measuring the dose received by the operator in the interventional procedure of the cerebral vascular system and finding the shielding material and shielding method which can effectively shield the exposure from the medical radiation. And to find a way to minimize it to the extent that it does not. As a result, when the newly designed shielding system with Nano Tungsten material was used, it was confirmed that the mean dose was reduced by 7.95% on average by the operator. Also, the PSNR results were measured to be 38.44 dB when using the designed shielding material, and it was confirmed that Nano Tungsten does not affect the image quality. In conclusion, the Nano Tungsten shielding material proved to be capable of significantly reducing the operator radiation dose, without affecting the image quality. The use of the above materials is expected to solve the problems related to the harmfulness and economical efficiency of the human body and the environment, which have recently become an issue of shielding materials.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.209-216
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• 2018

In the field of angiography and interventional radiology, it is said that the risk of radiation exposure to the eyes is high due to the characteristics of work, but currently divided dose assessment and management are not carried out in reality. Therefore, in this study, in order to evaluate the dose of the operator in the surgical environment and to analyze the shields, firstly, we selected the point where the operator is mainly located, evaluated the exposure dose of the eye after attaching the pocket dosimeter to the lateral angle point of the head and neck phantom, and evaluate shielding effect when wearing lead glasses that is currently commercialized. Secondly, we evaluated the tendency of the exposure dose of the eye and the shielding effect through simulation in the same geometric structure as the actual measurement. As a result, in the case of measurement using a dosimeter, the cumulative dose increased with the increase of the fluoroscopic time, and the tendency was different according to the position of the operator. Simulation results show that the dose distribution of the eye lens in the mathematical phantom is about 1.1 ~ 1.3 times higher than that of the cornea. Also, The protective effect of the lead glasses showed a shielding effect of at least 3.7 ~ 21.4% in each eye.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.342-349
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• 2014

Methods of establishment of AOEL (Acceptable Operator Exposure Level), application of oral absorption by country, and calculation of exposure dose for operator risk assessment in USA, EU and Korea were investigated. Oral absorption of 141 active substances for pesticides was also investigated, then operator risk assessment was conducted with AOEL including oral absorption and Korean AOEL. Internal dose converted to external dose with oral or dermal absorption in USA and EU, but external dose to which oral absorption was not applied was used for establishment of AOEL in Korea. Oral absorption of 50 active substances among 141 were below 80%. In case of application of oral absorption as a correction factor in below 80%, AOELs of about 36% active substances were considered to be lower than the current Korean AOELs. Operator risk assessment of 28 active substances among 50 active substances with oral absorption below 80% was conducted with EU AOELs. TER (Toxicity Exposure Ratio) of 12 plant protection products including chlorothalonil WG (Water-dispersible Granule) was less than 1 and the risk was high. Operator risk assessment of 24 active substances among 50 active substances with oral absorption below 80% was conducted with Korean AOELs. TER of 6 plant protection products including chlorothalonil WG were less than 1 and the risk was high. Operator risk assessment of 4 plant protection products not having Korean AOEL was conducted with converted EU AOEL into AOEL not including oral absorption. The results indicated TER of 4 products including daminozide WP (Wettable Powder) was over 1 and risk was low. 22 products except 6 products such as oxadiagyl SC (Suspension Concentration) were shown the same results of risk assessment between EU AOELs and Korean AOELs. As a result, it was considered that AOELs including oral absorption was possible to be used for operator risk assessment. It was considered operator risk assessment with AOEL including oral absorption was more like real assessment method, and improvement of assessment was needed for application to evaluate pesticides in registration.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.126-126
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• 2009

X-ray high-voltage generator is the most important part that can decide the radiation exposure dose affecting a patient or operator according to the characteristic. If decrease of X-ray radiation exposure dose and output characteristic of high-voltage generator is unstable, a patient or operator must be exposed to more radiation. This study measures and analyzes the exposure dose reproducibility and output characteristic according to a change of tube current on the various rectification methods of diagnostic X-ray equipment. It can find that quality bastardize and output is increased if voltage of X-ray tube is increased. Exposure dose reproducibility according to output of X-ray equipment is extremely excellent in inverter type, and is stable in order of following three-phase, a single-phase and condenser method. This study can find that the reply incidence of high-voltage generator is generated due to difference in rectification method, noise occurs in X-ray due to that, quality of an image is decreased due to that, and medical diagnosis can be failed due to that.

• Journal of the Korean Society of Radiology
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• v.10 no.3
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• pp.181-186
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• 2016

Cardiac angiography(CA) or cardiac intervention(CI) is one of the major examination methods applied to the detection of cardiovascular diseases using X-rays. These CA and CI procedures require radiation exposure to patients and physicians. We evaluated the radiation dose to cardiac operator during the each case of CA and CI procedures. The number of patients is 113 patients in CA and 34 patients in CI. Mean fluoroscopy time, mean cine time, and mean total cumulative dose area product(DAP) in patients during CA and CI was 165.9 sec vs. 1200.0 sec, 30.31 sec vs 107.5 sec, and $37130.3mGy.cm^2$ vs $213312.6mGy.cm^2$, respectively. Mean dose of thyroid, over chest apron and under chest apron in operator during CA and CI was 15.84 uSv vs 89.81 uSv, 20.16 uSv vs 123.20 uSv, and 0.30 uSv vs 2.40 uSv, respectively. Mean effective dose of operator during CI was about 6 times greater than during CA. Also there was significant inter-relationship between fluoroscopy or cine time and effective dose in operator during CA and CI(p=0.001 and p=0.001, respectively).

• Journal of Korean Neurosurgical Society
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• v.49 no.1
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• pp.37-42
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• 2011

Objective: The author measured levels of fluoroscopic radiation exposure to the surgeon's body based on the different beam directions during kyphoplasty. Methods: This is an observational study. A series of 84 patients (96 vertebral bodies) were treated with kyphoplasty over one year. The patients were divided into four groups based on the horizontal and vertical directions of the X-Ray beams. We measured radiation exposure with the seven dosimetry badges which were worn by the surgeon in each group (total of 28 badges). Twenty-four procedures were measured in each group. Cumulative dose and dose rates were compared between groups. Results: Fluoroscopic radiation is received by the operator in real-time for approximately 50% (half) of the operation time. Thyroid protectors and lead aprons can block radiation almost completely. The largest dose was received in the chest irrespective of beam directions. The lowest level of radiation were received when X-ray tube was away from the surgeon and beneath the bed (dose rate of head, neck, chest, abdomen and knee: 0.2986, 0.2828, 0.9711, 0.8977, 0.8168 mSv, respectively). The radiation differences between each group were approximately 2.7-10 folds. Conclusion: When fluoroscopic guided-KP is performed, the X-Ray tube should be positioned on the opposite side of the operator and below the table, otherwise the received radiation to the surgeon's body would be 2.7-10 times higher than such condition.