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Evaluation of the Use of a Molybdenum Filter for Dose Reduction in Pediatric Digital X-ray Imaging
Park Su-Jin,Kim Jaehyuk,Han Jong Chul,Kim Jung-Ha,Kim Jung-Min,Kim Jong-Pil,Cho Minkook,Kim Jung Woo 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.12
Pediatric dosimetry requires extra attention as young children are three times more sensitive to radiation than the average population. Soft tissues of patients absorb low-energy photons without affecting useful diagnostic information. X-ray filters can decrease the exposure dose of radiation by removing low-energy photons from the X-ray beam. Several studies have dealt with the advantages of a conventional filter, copper (Cu), in pediatric digital X-ray radiography. Only a few studies, however, have examined the use of molybdenum (Mo) filters and their impact on the radiation dose and image quality in pediatric digital X-ray imaging. In this study, we investigated the impact of a Mo filter on the image quality and the entrance surface exposure (ESE) in pediatric X-ray imaging and assessed the potential of additional dose reduction compared to a conventional Cu filter. The performance of the Mo filter was investigated and compared with that of Cu filter. Two types of phantoms were used: a customized quantitative phantom (Phantom A) for quantitative comparison and a computational anthropomorphic extended cardiac-torso (XCAT) phantom for qualitative comparison. A clinical radiography system was modeled, and the clinical setting for pediatric chest X-ray imaging was considered. Geant4 simulations using Monte Carlo toolkits were performed to obtain the images for pediatric chest X-ray examinations. Quantitative and qualitative comparisons using the quantitative phantom (Phantom A) and the XCAT phantom, respectively, were performed for both filters. From the customized quantitative phantom study, the ESE for the Mo filter was compared with that for the Cu filter when contrast-to-noise ratio (CNR) was equal. In addition, to validate our Monte Carlo model, we compared simulated and experimentally acquired images. From the results, the ESE for the Cu filter was 22.62 μGy while the ESE for the Mo filter was 18.18 μGy for 5-mm soft tissue. The use of a Mo filter results in a reduction in the dose by 19.60%. From the XCAT phantom study, the image for the Mo filter was superior to that for Cu filter in terms of noise and recognition of blood vessels. The performance characteristics of the Mo filter were evaluated in terms of image quality and radiation dose by comparing those characteristics to the ones for a conventional Cu filter. Our results demonstrated that the use of the Mo filter can significantly reduce the radiation dose. Based on this result, Mo filters are recommended for use in pediatric digital X-ray imaging.
Kim Claire Junga,Kim Do-Kyong,Mun Sookyeong,Son Minkook 대한의학회 2024 Journal of Korean medical science Vol.39 No.6
This study measured the impact of the Decisions on Life-Sustaining Treatment Act by analyzing medical cost data from the National Health Insurance Service-National Sample Cohort. After identifying the patients who died in 2018 and 2019, the case and control groups were set using the presence of codes for managing the implementation of life-sustaining treatment with propensity score matching. Regarding medical costs, the case group had higher medical costs for all periods before death. The subdivided items of medical costs with significant differences were as follows: consultation, admission, injection, laboratory tests, imaging and radiation therapy, nursing hospital bundled payment, and special equipment. This study is the first analysis carried out to measure the impact of the Decision on LifeSustaining Treatment Act through a cost analysis and to refute the common expectation that patients who decided to withhold or withdraw life-sustaining treatment would go through fewer unnecessary tests or treatments.
Minkook Kim,Jae-Woo Lee,Byoung Kuk Lee 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1
In this paper, the bifurcation criteria for inductive power transfer (IPT) systems is suggested considering the inductive power pad losses. The bifurcation criteria for series-series (SS) and series-parallel (SP) topologies are derived in terms of the main parameters of the IPT system. For deriving precise criteria, power pad resistance is obtained by copper loss calculation and core loss analysis. Utilizing the suggested criteria, possibility of bifurcation occurrence can be predicted in the design process. In order to verify the proposed criteria, 50 W IPT laboratory prototype is fabricated and the feasibilities of the switching frequency and AC load resistance shift to escape from bifurcation are identified.
Kim, Minkook,Lee, Jae-Woo,Lee, Byoung Kuk The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.1
In this paper, the bifurcation criteria for inductive power transfer (IPT) systems is suggested considering the inductive power pad losses. The bifurcation criteria for series-series (SS) and series-parallel (SP) topologies are derived in terms of the main parameters of the IPT system. For deriving precise criteria, power pad resistance is obtained by copper loss calculation and core loss analysis. Utilizing the suggested criteria, possibility of bifurcation occurrence can be predicted in the design process. In order to verify the proposed criteria, 50 W IPT laboratory prototype is fabricated and the feasibilities of the switching frequency and AC load resistance shift to escape from bifurcation are identified.
Minkook Kim,Jongeun Byun,Byoung Kuk Lee 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.3
In this paper, performance of rectangular shaped magnetic power pads for inductive power transfer (IPT) system according to ferrite structure is analyzed. In order to evaluate the influences of ferrite structure, six cases of magnetic power pads are proposed. Self-inductance, coupling coefficient, quality factor, and coil to coil efficiency are compared as the displacement increases in the direction of x or y axis. For accurate estimation, finite element method (FEM) simulation is used and loss components of the power pads are numerically calculated and considered. Through the simulation and measured results, effectiveness of protrusive and enveloping ferrite structure is identified.
Kim, Minkook,Byun, Jongeun,Lee, Byoung Kuk The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.3
In this paper, performance of rectangular shaped magnetic power pads for inductive power transfer (IPT) system according to ferrite structure is analyzed. In order to evaluate the influences of ferrite structure, six cases of magnetic power pads are proposed. Self-inductance, coupling coefficient, quality factor, and coil to coil efficiency are compared as the displacement increases in the direction of x or y axis. For accurate estimation, finite element method (FEM) simulation is used and loss components of the power pads are numerically calculated and considered. Through the simulation and measured results, effectiveness of protrusive and enveloping ferrite structure is identified.