Dae-Cheol Kweon

Evaluation of the radiation dose to a phantom for various X-ray exposure factors performed using the dose area product in digital radiography

The aim of this study is to measure the dose area product (DAP) in digital radiography by using a DAP meter to determine the X-ray exposure. Pediatric X-ray examinations can be obtained for any radiographic examinations using the selected radiographic examination parameters (kVp and mAs), the DAP information recorded. The best peak signal-to-noise ratio (PSNR) at a fixed tube voltage of 70 kVp was obtained at tube currents of 20 and 32 mA, whereas the best PSNR at a fixed tube current of 25 mA was obtained at a tube voltage of 73 kVp. The fixed tube voltage of 70 kVp and the fixed tube current of 25 mA could help to obtain the best image quality and depict the spatial resolution of an anthropomorphic torso phantom radiographic examination. The normalized data over the DAP were provided to determine the patient dose from radiography.

Effects of Sleep Deprivation on the Sedation of Pediatric Patients Undergoing MRI Examinations

ABSTRACT Sedation is an essential factor for pediatric magnetic resonance imaging (MRI) procedure. A long-term failure of sedation has a detrimental effect on a 1 day test plan. Given this background, this study examined the effects of sedation using a sleep deprivation method in pediatric patients scheduled to undergo an MRI examination. The current study examined 54 patients (36 boys and 18 girls) with diseases, such as epilepsy, brain tumor, development delay, mental retardation, and cerebral infarction, who were treated at our medical institution from December 2009 to March 2010. The patients were classified into two groups: group A (n = 27) with sleep deprivation, and group B (n = 27) without sleep deprivation. The mean age of these patients was 4.2 years. Comparative analysis of groups A and B was performed to assess the success rate of pediatric sedation, the time elapsed until complete sedation had been achieved, and the frequency at which patients took Pocral syrup (chloral hydrate). In group A, patients were allowed to start sleep 1 hr later and were woken 1 hr earlier than their mean sleep time. According to this pretreatment, the rate of successful sedation, frequency of the administration of Pocral syrup, and the time elapsed until deep sedation had been achieved were measured. In group A, the rate of successful sedation was 100%, the mean time elapsed until deep sedation had been achieved was 23 min, and the mean frequency of Pocral syrup administration was 1.2 times. In addition, the proportions of patients who had achieved successful sedation after one-time use and two-time use of Pocral syrup were 77.8% and 22.2%, respectively. In group B, successful sedation was achieved in 89%, and the mean time elapsed until deep sedation was 39 min. The mean frequency of Pocral syrup administration was 1.5 times. The proportions of patients who had achieved successful sedation after one-time use and two-time use of Pocral syrup were 51.9% and 48.12%, respectively. The statistical significance was tested using a nonparametric analysis, Mann–Whitney U Test (p < 0.05). Other studies have reported that sleep deprivation had no significant effects. An actual comparison of the sleep-deprived and other patients showed that sleep deprivation affected the rate of successful sedation, the frequency of Pocral syrup administration, and the time elapsed until the patients were sedated. The rate of successful sedation was significantly higher in group A than in group B. The time elapsed until deep sedation had been achieved was also significantly shorter in group A than in group B. In addition, the frequency of Pocral syrup administration (administration dose) was significantly lower in group A than in group B. In conclusion, sleep deprivation increases the effectiveness of pediatric sedation in an MRI examination of pediatric patients and might assist in performing an MRI examination more efficiently in pediatric patients.

Comparison Study with Pain Assessment Tools of Pain Measurement in Children for Intravenous Catheter Placement in the Computed Tomography

Needle phobia of medical devices is a significant problem in children patients. We conducted study in 130 pediatric patients aged (mean age 10.5) who had venipuncture performed in a computed tomography. This review aims to explore the research available relating to three commonly used pain rating scales of children, the visual analogue scale(VAS), numeric pain rating scale(NPRS) and Wong-Baker faces pain scale(WBFPS) with scores. Its validity is supported by a strong positive correlation with the three-pain rating scales(correlations ranging from 0.70 to 0.92) measure in children. There were no significant differences between the means on the VAS and either of the pain rating scales. It has the advantage of being suitable for use with the most widely used metric for scoring(), and conforms closely to a linear interval scale. These scales presented moderate to good correlation and moderate agreement, sufficient for valid use in children. All three pain-rating scales are valid, reliable and appropriate for use in intravenous catheter placement.

HU Threshold Value for IV Catheter Fragment in Peripheral Vein of Volume Rendering 3D MDCT Imaging

To evaluate the HU value of the IV catheter fragment of CT on the accuracy and size in the peripheral vein. Pilot study of profile and table functions on PC by software was calculated of HU value of IV catheter fragment. This study demonstrates the utility of volume rendering technique to localize a small, subtle IV catheter, which can easily be reformatted of MDCT reformations. IV catheter fragment optimal image described as threshold range. Volume rendering of HU using a MDCT is an excellent method for evaluation the IV catheter fragment in three dimension.

Case Study of Quality Assurance for MDCT Image Quality Evaluation Using AAPM CT Performance Phantom

The increasing use of computed tomography (CT) as a diagnostic tool creates the need from and efficient means of evaluating the performance of the CT scanner now in use. Accordingly, acceptance testing and quality assurance of CT is of great importance. The aim of this study is to analyze of AAPM CT performance phantom in the CT accreditation program. The modular phantom offers the CT system with which to measure eight performance parameters. The parameters are listed of CT attenuation coefficient of water, noise, uniformity, spatial resolution, contrast resolution, slice thickness (5 and 10 mm), artifacts and alignment. The phantom evaluation was done by two radiologists. The acceptance testing protocol described here in demonstrates the successful of the guidelines for the quality assurance using AAPM CT performance phantom. We need to be upgraded for the CT image quality and make the standard reference of the quality assurance in the CT.

Evaluation of Usefulness in New Immobilization Device with 3D CT Angiography for Lower Extremity

Our objective was to develop and evaluate a non-invasive device for rigid immobilization and surface disease non-contact of the table in the lower extremity during CT angiography. The immobilization device consists of two components. The patient`s lower limb device stabilizing elements made of polyethylene resin soft materials, and pelvis parts foam pad is used for non-contact surface. In a Prospective study the lower extremity device was used in patients who underwent a CT angiography of the lower limb. Immobilization with our device was well tolerated by all patients. The quality of the resulting images in the popliteal and infrapopliteal region was rated by five-point scale. The rigid immobilization resulted in a complete absence of motion artifacts. The new device is an effective, well tolerated and easily used immobilization that is suitable of use in 3D lower extremity CT angiography.

Cerebral Activation Area Following Oxygen Administration using a 3 Tesla Functional MR Imaging

This study aim to investigate the effects of supply of oxygen enhances cerebral activation through increased activation in the brain and using a 3 Tesla fMRI system. Five volunteers (right handed, average age of 21.3) were selected as subjects for this study. Oxygen supply equipment that provides 30% oxygen at a constant rate of 15L/min was given using face mask. A 3 Tesla fMRI system using the EPI BOLD technique, and three-pulse sequence technique get of the true axial planes scanned brain images. The author can get the perfusion images of the brain by oxygen inhalation with susceptibility contrast EPI sequence at the volunteers. Complex movement consisted of a finger task in which subjects flexed and extended all fingers repeatedly in union, without the fingers touching each other. Both task consisted of 96 phases including 6 activations and rests contents. Post-processing was done on MRDx software program by using cross-correlation method. The result shows that there was an improvement in performance and also increased activation in several areas in the oxygen method. These finding demonstrates that while performing cognitive tasks, oxygen administration was due to increase of cerebral activation.