Ham-Gyum Kim

Changes in SNR and ADC According to the Increase in b Value in Liver Diffusion-Weighted Images

In the present study, changes in signal-to-noise ratio (SNR) and apparent diffusion coefficient (ADC) of the diffusion-weighted images in the normal livers were investigated using changes in b values in 1.5 T MR (magnetic resonance) instruments. Respective diffusion-weighted images and ADC map images were obtained from 20 healthy individuals by increasing b values from 50 to 400 and 800 s/mm2 using 1.5T MR scanner between January 2011 and November 2011. At each ADC map image obtained at each b value, ADCs in the right hepatic lobe, spleen and kidney were measured. As a result, ADCs of the right hepatic lobe, spleen and kidney have gradually decreased in the diffusion-weighted images in accordance with the reduced b value. This outcome may be used as preliminary data for applications to various abdominal diseases.

Analysis of stress, musculoskeletal disorders, and fatigue among broadcasting actors

[Purpose] The purpose of the study was to assess the health effects of broadcasting actors through a comprehensive research on their job stress, psychosocial stress, and fatigue and to investigate those factors having an impact on their health condition to present a basis for comparative studies and effective human resource management in the future. [Subjects and Methods] A survey was performed to analyze the relevance of the general features, job stress, psychosocial stress, and fatigue. [Results] Analysis of job stress, one of the characteristics of individuals, revealed that 32.4% of the subjects with less than 5 years of service, 55.5% of those with 6 to 10 years of service, and 52.4% of those with more than 10 years of service showed a high level of stress. Analysis of psychosocial stress, another characteristic of individuals, revealed that 13.4% of the nonsmokers had a high level of psychosocial stress, while 37.7% of smokers had a high level of psychosocial stress based on analysis of chronic disease and psychosocial health. [Conclusion] Based on this study of the stress and fatigue of broadcasting actors, it is expected that improvements can be made to promote their mental health conditions and, organizational safety and to promote effective human resource management.

Risk Factors for Musculoskeletal Symptoms Among Korean Broadcast Actors

BACKGROUND Musculoskeletal diseases (MSDs) are functional disabilities in the musculoskeletal area that occur when continuous damage to the muscles or tissues is caused by performing a repetitive task. These diseases are usually found in the waist, shoulder, neck, arm, and wrist. MSD is also referred to as cumulative trauma disorder, repetitive strain injury, occupational overuse syndrome, and visual display terminal, depending on the country. The condition is now commonly referred to as work-related musculoskeletal disorder. OBJECTIVES The aim of this study was to develop a prevention plan against musculoskeletal disease and to provide better health care to broadcast actors by understanding the association between musculoskeletal symptoms and working conditions. The results of the study can be utilized to maintain effective systematic resources to treat such diseases. METHODS A survey was conducted in Seoul between January 1 and May 10, 2014 with broadcast actors working in the South Korean entertainment industry. FINDINGS Tests with respect to musculoskeletal symptoms indicated that the study participants were likely to experience having musculoskeletal symptoms in the shoulders, waist, neck, leg/foot, hand/wrist/finger, and arm/elbow. Most of the participants reported pain on both sides of their shoulders and in their legs/feet or on the right side of the arm/elbow and in hand/wrist/finger. Pain lasted between 1 and 7 days, with an incidence of 33.8% in the neck, 36% in the shoulders, 33.3% in the arm/elbow, 47.4% in the hand/wrist/finger, 34.7% in the waist, and 39.3% in the leg/foot. CONCLUSIONS This study should prove useful in determining systematic and effective resources to prevent broadcast actors from developing MSD in the future.

Evaluation of dosimetry and image of very low-dose computed tomography attenuation correction for pediatric positron emission tomography/computed tomography: phantom study

In this study, phantom was used to evaluate attenuation correction computed tomography (CT) dose and image in case of pediatric positron emission tomography (PET)/CT scan. Three PET/CT scanners were used along with acryl phantom in the size for infant and ion-chamber dosimeter. The CT image acquisition conditions were changed from 10 to 20, 40, 80, 100 and 160 mA and from 80 to 100, 120 and 140 kVp, which aimed at evaluating penetrate dose and computed tomography dose indexvolume (CTDIvol) value. And NEMA PET Phantom™ was used to obtain PET image under the same CT conditions in order to evaluate each attenuation-corrected PET image based on standard uptake value (SUV) value and signal-to-noise ratio (SNR). In general, the penetrate dose was reduced by around 92% under the minimum CT conditions (80 kVp and 10 mA) with the decrease in CTDIvol value by around 88%, compared with the pediatric abdomen CT conditions (100 kVp and 100 mA). The PET image with its attenuation corrected according to each CT condition showed no change in SUV value and no influence on the SNR. In conclusion, if the minimum dose CT that is properly applied to body of pediatric patient is corrected for attenuation to ensure that the effective dose is reduced by around 90% or more compared with that for adult patient, this will be useful to reduce radiation exposure level.

The Utility Evaluation of Reconstructed 3-D Images by Maximum Intensity Projection in Magnetic Resonance Mammography and Cholangiopancreatography

The aim of this study was to evaluate the utility of 3-D images by comparing and analyzing reconstructed 3-D images from fast spin echo images of MRI cholangiopancreatography (MRCP) images using maximum intensity projection (MIP) with the subtraction images derived from dynamic tests of magnetic resonance mammography. The study targeted 20 patients histologically diagnosed with pancreaticobiliary duct disease and 20 patients showing pancreaticobiliary duct diseases, where dynamic breast MR (magnetic resonance) images, fast spin echo imaged of pancreaticobiliary duct, and 3-D reconstitution images using a 1.5T MR scanner and 3.0T MR scanner were taken. As a result of the study, the signal-to-noise ratio in the subtracted breast image before and after administering the contrast agent and in the reconstructed 3-D breast image showed a high ratio in the reconstructed image of lesional tissue, relevant tissue, and fat tissue. However, no statistically meaningful differences were found in the contrast-to-noise ratio of the two images. In the case of the MRCP image, no differences were found in the ratios of the fast spin echo image and reconstructed 3-D image.

Study on a method to improve T1 image contrast by the subtraction technique for 3.0 T brain examination

The purpose of this study is to describe the enhanced gray/white brain matter delineation achieved by a novel subtraction technique. We subtracted T2-weighted from T1-weighted images. The resulting images were analyzed for contrast-to-noise ratio and reader preference. Our results show superior outcomes for the subtracted images. This improvement could be used to better identify tumor enhancement or cortical dysplasia.

A study on quantitative analysis of exposure dose caused by patient depending on time and distance in nuclear medicine examination

This study evaluated possible actions that can help protect against and reduce radiation exposure by measuring the exposure dose for each type of isotope that is used frequently in nuclear medicine before performing numerical analysis of the effective half-life based on the measurement results. From July to August in 2010, the study targeted 10, 6 and 5 people who underwent an 18F-FDG (fludeoxyglucose) positron emission tomography (PET) scan, 99mTc-HDP bone scan, and 201Tl myocardial single-photon emission computed tomography (SPECT) scan, respectively, in the nuclear medicine department. After injecting the required medicine into the subjects, a survey meter was used to measure the dose depending on the distance from the heart and time elapsed. For the 18F-FDG PET scan, the dose decreased by approximately 66% at 90 min compared to that immediately after the injection and by 78% at a distance of 1 m compared to that at 0.3 m. In the 99mTc-HDP bone scan, the dose decreased by approximately 71% in 200 min compared to that immediately after the injection and by approximately 78% at a distance of 1 m compared to that at 0.3 m. In the 201Tl myocardial SPECT scan, the dose decreased by approximately 30% in 250 min compared to that immediately after the injection and by approximately 55% at a distance of 1 m compared to that at 0.3 m. In conclusion, the dose decreases by a large margin depending on the distance and time. In conclusion, this study measured the exposure doses by isotopes, distance from the heart and exposure time, and found that the doses were reduced significantly according the distance and the time.

A study on the evaluation of usefulness depending on the image reconstruction method in bone SPECT scan

The recent advances in image-processing techniques have led to the development of many methods to reduce the scan time without degrading the image quality. In particular, tomography has improved image reconstruction methods with the concomitant improvement of high-quality images. In this study, PRECEDENCE 16 was used to reconstruct images using the filtered back projection method, which is generally used, and the Astonish method and three-dimensional ordered-subsets expectation maximization method, which are based on repetition techniques. In qualitative and quantitative analysis of the reconstructed images, a comparison was made between images with different acquisition times and between images with the same acquisition time, which aimed at determining the optimal method for reconstructing high-quality images. A blind test for qualitative analysis confirmed almost no difference in image quality depending on the image acquisition time. Furthermore, in quantitative analysis, there was no significant difference in image quality depending on the image acquisition time. On the other hand, the results of the analysis in the image reconstruction method with the same acquisition time demonstrated a significant difference. The images reconstructed by the Astonish method, which uses a repetition technique, are believed to be excellent because they have high resolution and provide clinical diagnostic information. This study confirmed that the reconstruction method with a repetition technique could be used to improve image quality and reduce the scan time, despite not being in general use until recently due to the lengthy time needed for image reconstruction and lack of storage space.