• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.155-159
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• 2011

The purposed of this study were measured the radiation exposure of patients and workers by generators, and the protection state for radiation facilities. The subject of the study by X-ray generators in university hospitals of capital area, we measured the maximum irradiation condition of 80 kVp, 200 mA, 0.1 second in the control entrance, control room window, entrance of radiography, adjacent site. The leakage dose per week was which the control entrance was 0.11 mR/week, control room window was 0.15 mR/week, entrance of radiography was 0.12 mR/week and adjacent site was 0.06 mR/week with X-ray unit the mean And the leakage mean dose was 0.11 mR/week. Diagnostic X-ray tubes must ensure that the leakage radiation in the maximum leakage dose in week emitted by the tube outside the useful beam does not exceed certain levels provided by standards.

• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.168-173
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• 2011

This study investigated characteristics of dose distribution at junction field of X-ray and electron beams according to the method for fabricating the insert block on the electron cone. Insert block were fabricated to the divergency cutout block and the straight cutout block. For the 6 MV X-ray and 10 MeV nominal energy of electron beam, we was adjacent to the light field of X-ray and electron beam at a surface of matrix chamber and measured to beam profile of abutted field in the 0, 1, 2, 3 cm measurement depth. As a result, characteristics of dose distribution at junction field, straight block was existent that over dose area exceed the give dose more than 5% and under dose area with a rapid change in dose distribution. However, divergency block had remarkably decreased the over dose area caused by the lateral scattering effects of decrease, and being existed uniformity dose distribution in the junction field. Therefore, divergency block were the benefits of radiation dose delivery, in order to applied the clinical, measurement of electron beams according to the fabrication method of the block should be considered carefully.

• Journal of the Korean Society of Radiology
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• v.8 no.1
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• pp.1-10
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• 2014

The bi-plane cerebrovascular angiography radiation is done the radiation exposure at the forward and lateral direction as opposed to the one of the source. So, the exposure dose of radiation workers increases further. Therefore, the medical diagnostic radiation workers as well as patients is interested to ways to reduce the dose. The exposure dose of cerebral angiography and interventional radiology must be considered the primary radiation of X-ray tube directly, scattered primary radiation between lateral tube and lateral detector and relatively small secondary scatter radiation in the walls of room. The aim of study is that the exposure dose of primary and scatter radiation reduce as much as possible to install protection device of lateral protection than common shielding of table and ceiling. As a result, the dose of fluoroscopy was reduced approximately 3.64 times the gonads, thyroid approximately 3.13 times, 4.42 times around eyes. And the dose of DSA was reduced approximately 4.98 times the gonads, thyroid approximately 3.00 times, 1.67 times around eyes. Consequently, medical practitioners can be helpful for radiation dose-exposure for the lateral protection of bi-plane cerebrovascular angiography more than the common shield method in cerebrovascular angiography and interventional radiological procedures.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.147-151
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• 2019

In chest and abdomen CT scans, the radiation exposure doses by scattering lines were measured at the eyeball and thyroid. Radiation exposure was investigated by using shielding devices. The chest and abdomen CT scan protocols used in the real examination were applied to measure and compare radiation doses before and after the use of shielding devices at the eyeball and the thyroid. The radiaton doses were measured with OSLD dosimeters. Barium, tungsten sheets, goggles and neck shields were used to protect the scattered X-ray. The chest CT scans showed respectively 3.01 mSv and 6.21 mSv at the eyeball and the thyroid by the scattered X-ray. The abdomen CT scans showed 0.55 mSv and 3.22 mSv for the eyeball and the thyroid respectively. Barium and tungsten sheets had 11% to 13% protection rates at the eyeball and the thyroid for chest CT scan, and 34% to 49% reduction in radiation dose for the abdomen CT scan. Because of the significant radiation dose, which causes cataracts and thyroid cancer by the repeated and continuous radiation exposure, for the chest and the abdomen CT scans, it is required to use shielding devices to reduce radiation dose for examinations.

• Progress in Medical Physics
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• v.3 no.2
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• pp.1-12
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• 1992

For intraoperative radiation therapy using electron beams, a cone system to deliver a large dose to the tumor during surgical operation and to save the surrounding normal tissue should be developed and dosimetry for the cone system is necessary to find proper X-ray collimator setting as well as to get useful data for clinical use. We developed a docking type of a cone system consisting of two parts made of aluminum: holder and cone. The cones which range from 4cm to 9cm with 1cm step at 100cm SSD of photon beam are 28cm long circular tubular cylinders. The system has two 26cm long holders: one for the cones larger than or equal to 7cm diamter and another for the smaller ones than 7cm. On the side of the holder is an aperture for insertion of a lamp and mirror to observe treatment field. Depth dose curve. dose profile and output factor at dept of dose maximum. and dose distribution in water for each cone size were measured with a p-type silicone detector controlled by a linear scanner for several extra opening of X-ray collimators. For a combination of electron energy and cone size, the opening of the X-ray collimator was caused to the surface dose, depths of dose maximum and 80%, dose profile and output factor. The variation of the output factor was the most remarkable. The output factors of 9MeV electron, as an example, range from 0.637 to 1.549. The opening of X-ray collimators would cause the quantity of scattered electrons coming to the IORT cone system. which in turn would change the dose distribution as well as the output factor. Dosimetry for an IORT cone system is inevitable to minimize uncertainty in the clinical use.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.10
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• pp.129-133
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• 2009

Considerable attention has been focused on digital X-ray systems with transmission. However, only a few attempts have been made using X-ray backscatter systems. This study developed a Data Acquisition System (DAS) for backscattered X-rays. The imaging system used X-ray backscatter at low energy levels, which has unique advantages in terms of acquiring information that cannot be obtained using the transmission system. Such systems are of potential benefit in the medical, industrial, security and military fields because of its practical benefits and the low doses used. The developed system is a similar body scan system. Experiments were carried out using a several metal materials and a fish, which produces results similar to those obtained using the human body during X-ray testing.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.329-336
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• 2014

Purpose : To evaluate the dose on a contralateral breast and the usefulness of shielding according to the distance between the contralateral breast and the side of the beam by breast size when patients who got breast implant receive radiation therapy. Materials and Methods : We equipped 200 cc, 300 cc, 400 cc, and 500 cc breast model on the human phantom (Rando-phantom), acquired CT images (philips 16channel, Netherlands) and established the radiation treatment plan, 180 cGy per day on the left breast (EclipseTM ver10.0.42, Varian Medical Systems, USA) by size. We set up each points, A, B, C, and D on the right(contralateral) breast model for measurement by size and by the distance from the beam and attached MOSFET at each points. The 6 MV, 10 MV and 15 MV X-ray were irradiated to the left(target) breast model and we measured exposure dose of contralateral breast model using MOSFET. Also, at the same condition, we acquired the dose value after shielding using only Pb 2 mm and bolus 3 mm under the Pb 2 mm together. Results : As the breast model is bigger from 200 cc to 500 cc, The surface of the contralateral breast is closer to the beam. As a result, from 200 cc to 500 cc, on 180 cGy basis, the measurement value of the scattered ray inclined by 3.22 ~ 4.17% at A point, 4.06 ~ 6.22% at B point, 0.4~0.5% at C point, and was under 0.4% at D point. As the X-ray energy is higher, from 6 MV to 15 MV, on 180 cGy basis, the measurement value of the scattered ray inclined by 4.06~5% at A point, 2.85~4.94% at B point, 0.74~1.65% at C point, and was under 0.4% at D point. As using Pb 2 mm for shield, scattered ray declined by average 9.74% at A and B point, 2.8% at C point, and is under 1% at D point. As using Pb 2 mm and bolus together for shield, scattered ray declined by average 9.76% at A and B point, 2.2% at C point, and is under 1% at D point. Conclusion : Commonly, in case of patients who got breast implant, there is a distance difference by breast size between the contralateral breast and the side of beam. As the distance is closer to the beam, the scattered ray inclined. At the same size of the breast, as the X-ray energy is higher, the exposure dose by scattered ray tends to incline. As a result, as low as possible energy wihtin the plan dose is good for reducing the exposure dose.

• Journal of radiological science and technology
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• v.42 no.5
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• pp.365-371
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• 2019

We have developed and applied a diagnostic Multi-Leaf Collimator (MLC) to optimized the X-ray field in medical imaging and the usefulness evaluated through the fusion of infrared image and X-ray image acquired by infrared camera. The hand and skull radiography with multi-leaf collimator(MLC) showed significant area dose reductions of 22.9% and 31.3% compared to ARC and leakage dose was compliant with KS A 4732. Also scattering doses of 50 cm and 100 cm showed a significant decrease to confirm the usefulness of MLC. It was confirmed that the fusion of infrared images with an adjustable degree of transparency was possible in the X-ray images. Therefore, fusion of anatomical information with physiological convergence is expected to contribute and improvement of diagnostic ability. In addition, the feasibility of convergence X-ray imaging and DITI devices and the possibility of driving MLC with infrared images were confirmed.

• Journal of radiological science and technology
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• v.42 no.6
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• pp.477-482
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• 2019

Recently, due to the increased use of medical radiation, the radiation exposure of radiation workers should be considered as well as medical exposure of patients. And it is recommended to close the door during radiography. however, In this study, when the door was inevitably opened for radiography, the proposed method was to install the shield as a method of reducing the exposure dose. And its efficiency was analyzed. In simple chest radiography, the measurement point was changed according to the measurement location. Dose rate were measured 10 times for each condition using a dosimeter. And the average value was derived. Using this, the change of dose according to the opening and closing of the door and the installation of the shield was analyzed. Using this, we compared and analyzed the dose change according to the door opening and closing and the installation of the shield, and significance was verified through the SPSS ver. 24. Depending on whether the door was opened or closed, 11,215.35%, 159.0%, 101.9% increased in front of the door in the consol room, behind the wall and behind the lead glass. Depending on the installing of the shield, the 49.2%, 29.6%, 19.9%, 30.6% decrease in front of the door in the examination and consol room, behind the wall and lead glass. In addition, statistical analysis was showed that there were significant differences in both the results according to whether the door was opened or closed and shielding(p<.05). Close the door during radiography. However, when the door should be opened, it was confirmed that the dose rate were reduced by installing the shield. Therefore, to optimize radiation protection, it is recommended to install shields when opening the door.

• 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.