• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.2
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• pp.243-253
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• 2022

Spent filters with a high radiation dose rate of 2 mSv·hr^-1 or more are not easily managed. So far, the Korean policy for spent filter disposal is to store them temporarily at nuclear power plants until the waste filters can be easily managed. Nuclear power plant decommissioning in Korea is starting with Kori unit 1. Volume reduction of waste generated during decommissioning can reduce the cost and optimize the space usage at disposal site. Therefore, efficient volume reduction is a very important factor during the decommissioning process. A conceptual method, based on the experiences of developing 200 and 800 ton compactors at Orion EnC, has been developed considering worker exposure with the followings a crusher (upgrade of compaction efficiency), an automatic dose measuring system with a NaI(Tl) detector, a shield box, an inner drum to prepare for easy handling of drums and packaging, a 30 ton compactor, and an automatic robot system. This system achieves a volume reduction ratio of up to 85.7%; hence, the system can reduce the disposal cost and waste volume. It can be applied to other types of wastes that are not easily managed due to high dose rates and remote control operation necessity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1871-1876
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• 2013

In this study, we developed and characterized the shielding properties of dose reduction fiber (DRF, Buffalo Co.) sheet during brain and chest CT examinations. The DRF sheet was composed of $1{\sim}500{\mu}m$ oxide Bismuth ($Bi_2O_3$) and 5 ~ 50 nm nano-barium sulfate ($BaSO_4$). Phantom and clinical studies were performed for characterization of the DRF shielding properties. In clinical study, we measured doses of eye, chest, abdomen and reproductive system of 60 patients in 3 hospitals during brain and chest CT examinations. We could determined the shielding effect of the DRF by comparing the doses when we used the DRF sheet or not. When we used the sheet during CT examination, the scattered dose were reduced about 20~50%. So, we suggest that the fiber should be used in radiological examinations for reducing patients doses.

• Journal of radiological science and technology
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• v.44 no.3
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• pp.173-181
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• 2021

The purpose of this study was to reduce dose while maintaining image quality during digital radiographic examination of paranasal sinus by using the automatic exposure control (AEC) system. The tube voltage was set as six stages that increased by about 10 kVp to 70 kVp, 81 kVp, 90 kVp, 102 kVp, 109 kVp and 117 kVp. And then the AEC system conditions were consisted of 9 setting environments, that change mode of the sensitivity (S200, S400, S800) and the density (+2.5, 0, -2.5). We measured automatically exposed tube current (mAs) under 54 conditions with combined these, and assessed SNR and PSNR through the acquired images. In addition, four radiologists performed a qualitative assessment of the acquired images for each combination on a five-point scale of the Likert. As a result, the lowest dose and the highest values of SNR and PSNR in images with a qualitative assessment more than 4 point were the AEC control factors of 90 kVp, S800, D2.5. We applied this condition to the clinical trial, it showed an effect of 83.1% reduction in exposure radiation dose (mR). Therefore, AEC system could be used as dose reduction technology if it understood and used related regulatory factors and physical characteristics.

• Korean Journal of Digital Imaging in Medicine
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• v.12 no.1
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• pp.19-25
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• 2010

This study is mainly for the reduction of exposure dose by using a heavy elements filter(Gd) in the digital radiology. They contained heavy elements filter of Gd and X-ray beam hardening filters such as Al and Cu. According to the results of experimental evaluation, X-ray property was not changed with variety of kVp in the case of the Gd filter. The surface dose and absorption dose were increased in order of Cu and Al. The contrast of image showed the higher value in order of Cu, Al and Gd. While the use of Gd has increased the numerical value of the CR image, and grayscale has decreased noise value of the DR image.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.385-390
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• 2009

The Pneumatic Reduction and VCUG (Voiding Cystourethrography) are commonly used in the paediatric age group. The procedures had a particularly long fluroscopic screening time, despite a successful outcome for paediatric patients. Pneumatic Reduction and VCUG almost invariably requires fluoroscopic guidance which does confer a radiation dose. This article contains suggestions on how the radiation dose to paediatric patients from Pneumatic Reduction and VCUG can be made "as low as reasonably achievable" (ALARA). The aim of our study was eliminated in spot image applying the FluoroGrab, which has function of capturing an image of interest area from the picturing while fluoroscopic procedures. FluoroGrab has clinical value equivalent to the spot image, and is applied to the most recent fluoroscopic procedures. The radiologist and the radiographers should consider new option for decreasing the radiation exposure delivered to paediatric patients by making equipment modifications to the fluoroscopy to optimize radiation exposure reduction techniques. Thus, we propose the FluoroGrab instead of spot exposure for the reduction of patient exposure dose in paediatric, and try to confirm the effect of the mitigating amount of radiation exposure to paediatric patients when pneumatic reduction and VCUG. Fluorograb is the safe and useful method that shows the equivalent level of accuracy to spot exposure, and to minimize the radiation load to paediatric patients are to be the substitute for the spot exposure for Pneumatic Reduction and VCUG.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.1167-1172
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• 2009

The Pneumatic Reduction and VCUG (Voiding Cystourethrography) are commonly used in the paediatric age group. The procedures had a particularly long fluroscopic screening time, despite a successful outcome for paediatric patients. Pneumatic Reduction and VCUG almost invariably requires fluoroscopic guidance which does confer a radiation dose. This article contains suggestions on how the radiation dose to paediatric patients from Pneumatic Reduction and VCUG can be made "as low as reasonably achievable" (ALARA). The aim of our study was eliminated in spot image applying the FluoroGrab, which has function of capturing an image of interest area from the picturing while fluoroscopic procedures. FluoroGrab has clinical value equivalent to the spot image, and is applied to the most recent fluoroscopic procedures. The radiologist and the radiographers should consider new option for decreasing the radiation exposure delivered to paediatric patients by making equipment modifications to the fluoroscopy to optimize radiation exposure reduction techniques. Thus, we propose the FluoroGrab instead of spot exposure for the reduction of patient exposure dose in paediatric, and try to confirm the effect of the mitigating amount of radiation exposure to paediatric patients when pneumatic reduction and VCUG. Fluorograb is the safe and useful method that shows the equivalent level of accuracy to spot exposure, and to minimize the radiation load to paediatric patients are to be the substitute for the spot exposure for Pneumatic Reduction and VCUG.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.393-400
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• 2020

Unlike conventional radiographic examinations, angiointerventional procedures have a high risk of radiation exposure to patients or operators due to prolonged radiation exposure time. This study was undertaken to examine effects of reducing the radiation risk by applying dose reduction fiber (DRF) shielding cloth during angiography. To investigate the properties of DRF shielding cloth, we measured the scattered radiation below and above a human phantom using a glass dosimeter, at site distances 10 cm away from the irradiated field. The results obtained reveal a 15 ~ 31% reduction of scattered radiation in the irradiation field, and 53 ~ 70% reduced radiation measured after phantom transmission. Taken together, our data indicate that application of DRF shielding cloth for radiation reduction at non-procedural sites during interventional procedure results in reduction of scattered doses to patients and operators, without affecting the medical examinations. We propose the use of DRF shielding during angiointerventional procedures, in order to reduce the risk of radiation exposure of patients and operators.

• Progress in Medical Physics
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• v.28 no.1
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• pp.27-32
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• 2017

We investigated the effect of a commercial iterative reconstruction technique (iDose, Philips) on the image quality and the dose calculation for the treatment plan. Using the electron density phantom, the 3D CT images with five different protocols (50, 100, 200, 350 and 400 mAs) were obtained. Additionally, the acquired data was reconstructed using the iDose with level 5. A lung phantom was used to acquire the 4D CT with the default protocol as a reference and the low dose (one third of the default protocol) 4D CT using the iDose for the spine and lung plans. When applying the iDose at the same mAs, the mean HU value was changed up to 85 HU. Although the 1 SD was increased with reducing the CT dose, it was decreased up to 4 HU due to the use of iDose. When using the low dose 4D CT with iDose, the dose change relative to the reference was less than 0.5% for the target and OARs in the spine plan. It was also less than 1.1% in the lung plan. Therefore, our results suggests that this dose reduction technique is applicable to the 4D CT image acquisition for the radiation treatment planning.

• Radiation Oncology Journal
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• v.32 no.2
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• pp.84-94
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• 2014

Purpose: To quantify the cardiac dose reduction during breathing adapted radiotherapy using Real-time Position Management (RPM) system in the treatment of left-sided breast cancer. Materials and Methods: Twenty-two patients with left-sided breast cancer underwent CT scans during breathing maneuvers including free breathing (FB), deep inspiration breath-hold (DIBH), and end inspiration breath-hold (EIBH). The RPM system was used to monitor respiratory motion, and the in-house self respiration monitoring (SRM) system was used for visual feedback. For each scan, treatment plans were generated and dosimetric parameters from DIBH and EIBH plans were compared to those of FB plans. Results: All patients completed CT scans with different breathing maneuvers. When compared with FB plans, DIBH plans demonstrated significant reductions in irradiated heart volume and the heart $V_{25}$, with the relative reduction of 71% and 70%, respectively (p < 0.001). EIBH plans also resulted in significantly smaller irradiated heart volume and lower heart $V_{25}$ than FB plans, with the relative reduction of 39% and 37%, respectively (p = 0.002). Despite of significant expansion of lung volume using inspiration breath-hold, there were no significant differences in left lung $V_{25}$ among the three plans. Conclusion: In comparison with FB, both DIBH and EIBH plans demonstrated a significant reduction of radiation dose to the heart. In the training course, SRM system was useful and effective in terms of positional reproducibility and patient compliance.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.289-295
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• 2017

The aim of this study was to evaluate the dose comparison using Radon phantom with 5 mm and 10 mm tissue equivalent materials, FIF, Wedge(15, 30 angle) and IMRT, to reduce the skin dose of the contralateral breast during breast cancer radiation therapy(Total dose: 50.4Gy). The dose was measured for each treatment plan by attaching to the 8 point of the contralateral breast of the treated region using a optical-stimulated luminance dosimeter(OSLD) as a comparative dose evaluation method. Of the OSLD used in the study, 10 were used with reproducibility within 3%. As a result, the average reduction rates of 5 mm and 10 mm in the FIF treatment plan were 37.23 cGy and 41.77 cGy, respectively, and the average reduction rates in the treatment plan using Wedge $15^{\circ}$ were 70.69 cGy and 87.57 cGy, respectively. The IMRT showed a reduction of 67.37 cGy and 83.17 cGy, respectively. The results of using bolus showed that as the thickness of the bolus increased in all treatments, the dose reduction increased. We concluded that mastectomy as well as general radiotherapy for breast cancer would be very effective for patients who are more likely to be exposed to scattered radiation due to a more demanding or complex treatment plan.