• 대한의용생체공학회:의공학회지
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• 제26권1호
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• pp.31-35
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• 2005

A novel synthetic aperture method for real-time three-way dynamic focusing is proposed, which provides lateral beam patterns represented as the product of Fourier transforms of transmit subaperture, receive subaperture, and a synthetic window function. In the proposed method, all array elements are fired individually and for each firing echo signals are recorded from all elements of a receive subaperture moving along an array with the transmit element. The three-way dynamic focusing is then achieved by employing a synthetic aperture algorithm for two-way dynamic focusing and a synthetic focusing method for transmit dynamic focusing. Both theoretical analysis and computer simulation results show that the proposed method produces ultrasound beams with improved lateral resolution at all depths compared to the conventional phased array imaging and synthetic aperture focusing methods.

• 대한의용생체공학회:의공학회지
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• 제30권1호
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• pp.66-78
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• 2009

A mobile ultrasound scanner developed for use in point-of-care applications is introduced, which can not only provide ultrasound images but can also measure various bio-signals. The mobile ultrasound scanner is also designed to meet the demanding requirements for point-of-care diagnosis, such as battery-powered operation, portability in terms of size and weigh, and real-time wireless communications capability for remote diagnosis. To meet these requirements, an efficient beamforming method for high resolution imaging with a small number of active elements, a hardware efficient beamformer architecture, and echo processing algorithms with greatly reduced computational complexity have been developed. Experimental results show that the prototype mobile ultrasound scanner is fully functional and satisfies most of the design requirements.

• The Journal of Korean Physical Therapy
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• 제23권3호
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• pp.37-42
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• 2011

Purpose: The principal objective of this study was to evaluate the power output of ultrasound in Korean clinics and compare the value with Korean and global standards. Methods: A total of 69 units were measured for ultrasound power output. The normal range of power output level was ${\pm}30%$ of the output set according to KFDA standards. Device model, manufacturer, ERA, and BNR were obtained via simple questionnaires. A portable ultrasound power meter was used for output measurement. Results: 37 machines, with reported ERA values, were assessed for power output per unit area. Of these machines, 13 (37.14%) were considered to be compliant with US FDA standards at 0.5, 1.0, 1.5, $20W/cm^2$ and 18 (51.43%) were considered within KFDA standards. The remainder of the machines were outside the standard error and evidenced irregular output levels, even though most of them were the same model. Conclusion: Appropriate ultrasound intensity is incredibly important for safety and effective use. Therefore, the KFDA standards regarding ultrasound may require revision in light of global standards, including BNR and ERA additionally, attention should be paid to regular calibration for safe use in clinical practice.

• 대한방사선기술학회지:방사선기술과학
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• 제43권5호
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• pp.367-374
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• 2020

The purpose of this study is to understand the infection prevention system and infection management perception of Ultrasound diagnostic room in medical institutions by sonographer's in general practitioner, semi and general hospitals. As a research method, a statistical analysis was conducted by surveying a total of 20 items in four category to determine the infection perception of sonographer's according to gender, age, working institution, and working period. As a result of infection awareness, males were in the ultrasound gel management category, women were in the transducer management category, all age groups were in the transducer management system category, and the General Practitioner, semi and general hospitals. were in the transducer management system category, and general hospitals showed a high degree of infection awareness in the category of disinfection and sterilization, and in the category of transducer management in the entire working period. In the results of the analysis of the correlation between the sub-factors of the perception of infection control in the Ultrasound diagnostic room the degree of correlation between each category showed a middle degree correlation(r>0.5) and a significant difference by category(p<.01). In conclusion, the prevention of infection in the ultrasound diagnostic room, which sonographer's firms think, was found to be the most efficient ultrasound diagnostic room infection control to implement transducer and gel management in accordance with the principles of disinfection and sterilization.

• 대한의용생체공학회:의공학회지
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• 제43권3호
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• pp.147-152
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• 2022

This research is to measure real-time temperature distribution inside a tissue-mimicking phantom for the safety and effectiveness evaluations of focused ultrasound (FUS) device capable of linear scanning stimulation. Since the focusing area of the FUS stimulation device is smaller than diameter of conventional thermal probe and keeps moving, it is impossible to monitor temperature distribution inside the phantom. By using the phantom with a thin film temperature sensor array inserted, real-time temperature change caused by the FUS device was measured. The translation of the measured temperature peak was also tracked successfully. The present phantom had been experimentally proven to be applicable to validate the performance and safety of the therapeutic ultrasound devices.

• Journal of Acupuncture Research
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• 제39권2호
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• pp.105-114
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• 2022

Background: The objective structured clinical examination (OSCE) is used in the colleges of Korean Medicine, but few studies have validated the OSCE evaluation criteria or post-education questionnaires. Diagnostic ultrasound is used in Korean medicine treatment including acupuncture, acupotomy, and pharmacopuncture to increase the safety and efficacy of treatment. We aimed to develop and validate a OSCE checklist and questionnaire for diagnostic musculoskeletal ultrasound training. Methods: A OSCE checklist and rubric for diagnostic ultrasound training, and questionnaire was developed using literature research. Eight expert panelists verified each draft item in a single-round survey. Items with a content validity ratio (CVR) < 0.75 were excluded or modified to reflect the experts' opinions. Results: The OSCE checklist and rubric for diagnostic ultrasound training focusing on volar wrist and carpal tunnel syndrome included: 15 items revised according to CVR and expert opinions, the pre-examination procedure, structures to be identified by ultrasound, scans with 2 diagnostic criteria for carpal tunnel syndrome, an explanation of the exam results, and the post exam procedure. The questionnaire consisted of 15 items, including the overall evaluation of training, the effect of the OSCE, and the perception of the ultrasound. All 6 self-evaluation items were not revised, as they had a CVR of ≥ 0.75. Conclusion: An ultrasound OSCE for scanning the volar wrist and diagnosing carpal tunnel syndrome was developed using 15 validated tasks, 15 survey questions about ultrasound training, and 6 questions for self-evaluation. These results may be used in the future for education in diagnostic ultrasound.

• The Korean Journal of Pain
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• 제35권2호
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• pp.183-190
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• 2022

Background: To compare ultrasound-guided pulsed radiofrequency (PRF) of the genicular nerve with the genicular nerve block using local anesthetic and steroid for management of osteoarthritis (OA) knee pain. Methods: Thirty patients with OA knee were randomly allocated to receive either ultrasound-guided PRF of the genicular nerve (PRF group) or nerve block with bupivacaine and methylprednisolone acetate (local anesthetic steroid [LAS] group). Verbal numeric rating scale (VNRS) and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) scores were measured at pre-procedure and 1-, 4-, and 12-weeks post-procedure. Results: VNRS scores decreased significantly (P < 0.001) in both the groups at 12 weeks and other follow up times compared to baseline. Seventy-three percent of patients in the PRF group and 66% in the LAS group achieved effective pain relief (≥ 50% pain reduction) at 12 weeks (P > 0.999). There was also a statistically significant (P < 0.001) improvement in WOMAC scores in both groups at all follow up times. However, there was no intergroup difference in VNRS (P = 0.893) and WOMAC scores (P = 0.983). No complications were reported. Conclusions: Both ultrasound-guided PRF of the genicular nerve and blocks of genicular nerve with local anesthetic and a steroid provided comparable pain relief without any complications. However, PRF of the genicular nerve is a procedure that takes much more time and equipment than the genicular nerve block.

• 대한의용생체공학회:의공학회지
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• 제28권6호
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• pp.803-810
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• 2007

Although synthetic aperture focusing techniques can improve the spatial resolution of ultrasound imaging, they have not been employed in a commercial product because they require a real-time N-channel beamformer with a tremendously increased hardware complexity for simultaneous beamforming along M multiple lines. In this paper, a hardware-efficient beamformer architecture for synthetic aperture focusing is presented. In contrast to the straightforward design using NM delay calculators, the proposed method utilizes only M delay calculators by sharing the same values among the focusing delays which should be calculated at the same time between the N channels for all imaging points along the M scan lines. In general, synthetic aperture beamforming requires M 2-port memories. In the proposed beamformer, the input data for each channel is first upsampled with a 4-fold interpolator and each polyphase component of the interpolator output is stored into a 2-port memory separately, requiring 4M 2-port memories for each channel. By properly limiting the area formed with the synthetic aperture focusing, the input memory buffer can be implemented with only 4 2-port memories and one short multi-port memory.

• The Korean Journal of Pain
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• 제26권3호
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• pp.249-254
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• 2013

Background: The pes anserine bursa lies beneath the pes anserine tendon, which is the insertional tendon of the sartorius, gracilis, and semitendinosus muscles on the medial side of the tibia, but it can lie in different sites in the medial knee. Accurate diagnosis of the position of the bursa is critical for diagnostic and therapeutic goals. The aim of this study was to evaluate sonoanatomic variations of the pes anserine bursa in the medial knee. Methods: One hundred seventy asymptomatic volunteers were enrolled in this study. Using ultrasound imaging (transverse approach, 7-13 MHz linear array probe) the sonoanatomic position of the pes anserine bursa and its relation to the pes anserine tendon were evaluated. Additionally, we evaluated the sonoanatomic variation of the saphenous nerve. Results: The position of the pes anserine bursa was between the medial collateral ligament and the pes anserine tendons in 21.2%/18.8% (males/females) of subjects; between the pes anserine tendons and the tibia in 67.1%/64.7% (m/f); and among the pes anserine tendons in 8.2%/12.9% (m/f). No significant differences in the position of the bursa existed between males and females. The saphenous nerve was found within the pes anserine tendons in 77.6%/74.1% (m/f) of subjects, but outside the pes anserine tendons in 18.8%/15.3% (m/f). Visibility of sonoanatomic structures was not related to either gender or BMI. Conclusions: Ultrasound provides very accurate information about variations in the pes anserine bursa and the saphenous nerve. This suggests that our proposed ultrasound method can be a reliable guide to facilitate approaches to the medial knee for diagnostic and therapeutic objectives.

• 대한의용생체공학회:의공학회지
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• 제41권1호
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• pp.48-54
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• 2020

In this paper, we deal with a liver fibrosis classification problem using ultrasound B-mode images. Commonly representative methods for classifying the stages of liver fibrosis include liver biopsy and diagnosis based on ultrasound images. The overall liver shape and the smoothness and roughness of speckle pattern represented in ultrasound images are used for determining the fibrosis stages. Although the ultrasound image based classification is used frequently as an alternative or complementary method of the invasive biopsy, it also has the limitations that liver fibrosis stage decision depends on the image quality and the doctor's experience. With the rapid development of deep learning algorithms, several studies using deep learning methods have been carried out for automated liver fibrosis classification and showed superior performance of high accuracy. The performance of those deep learning methods depends closely on the amount of datasets. We propose an enhanced U-net architecture to maximize the classification accuracy with limited small amount of image datasets. U-net is well known as a neural network for fast and precise segmentation of medical images. We design it newly for the purpose of classifying liver fibrosis stages. In order to assess the performance of the proposed architecture, numerical experiments are conducted on a total of 118 ultrasound B-mode images acquired from 78 patients with liver fibrosis symptoms of F0~F4 stages. The experimental results support that the performance of the proposed architecture is much better compared to the transfer learning using the pre-trained model of VGGNet.