• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.163-173
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• 2014

When evaluating the spatial resolution images and evaluation of low contrast resolution using CT standard phantom, and might present a automated quantitative evaluation method for minimizing errors by subjective judgment of the evaluator be, and try to evaluate the usefulness. 120kVp and 250mAs, 10mm collimation, SFOV(scan field of view) of 25cm or more than, exposure conditions DFOV(display field of view) of 25cm, and were evaluated the 24 passing images and 20 failing images taken using a standard reconstruction algorithm by using the Nuclear Associates, Inc. AAPM CT Performance Phantom(Model 76-410). Quantitative evaluation of low contrast resolution and spatial resolution was using an evaluation program that was self-developed using the company Mathwork Matlab(Ver. 7.6. (R2008a)) software. In this study, the results were evaluated using the evaluation program that was self-developed in the evaluation of images using CT standard phantom, it was possible to evaluate an objective numerical qualitative evaluation item. First, if the contrast resolution, if EI is 0.50, 0.51, 0.52, 0.53, as a result of evaluating quantitatively the results were evaluated qualitatively match. Second, if CNR is -0.0018~-0.0010, as a result of evaluating quantitatively the results were evaluated qualitatively match. Third, if the spatial resolution, as a result of using a image segmentation technique, and automatically extract the contour boundary of the hole, as a result of evaluating quantitatively the results were evaluated qualitatively match.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.4
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• pp.335-341
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• 2020

This study investigates the association of the AFB stain with the cycle threshold (Ct) value of the Cobas TaqMan MTB test (CTM test, Roche Diagnostics, Basel, Switzerland), and it establishes the base data for semi-quantitative identification of M. tuberculosis by the Ct value. CTM test were simultaneously conducted on 8,389 specimens submitted to the Samsung Medical Center from January 2015 to December 2015, and the results were analyzed and compared retrospectively investigates the association of the AFB stain with the Ct value of the CTM test, and it establishes the base data for semi-quantitative identification of M. tuberculosis by the Ct value. The Ct values for 135 positive specimens of the CTM were inversely correlated with the AFB stain (rs=-0.545, P<0.01). When the Ct value of the CTM test and the time to positivity (TTP) of the mycobacteria cultures were verified based on the AFB stain, they were found to have a positive correlation (rs=0.136, P<0.01). The negative correlation between the CTM test and the AFB stain grade was demonstrated. The clinical significance was verified by applying these criteria to the clinical results. The semi-quantitative criteria of this study can be used to facilitate the rapid isolation of patients with active tuberculosis and infection control in the hospital.

• Journal of the Korean Society of Radiology
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• v.5 no.5
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• pp.255-260
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• 2011

We wanted to evaluate the usefulness of three-dimensional reconstructive images using computed tomography for rib fracture patients. The reconstruction used in clinical multi planar reformation(MPR), volume rendering technique(VRT), and image data using quantitative methods and qualitative methods were compared. Much more, the artifact shadow was minimized to reconstruct with 3D volumetric image by using an law data in the analysis of the reconstructive image and chest CT scan of the evaluation result fractures of the thoracic patient. And we could know that the fractures of the thoracic determination and three dimension volume image reconstruction time were reduced.

• The Korean Journal of Nuclear Medicine Technology
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• v.28 no.1
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• pp.35-40
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• 2024

Purpose: To improve the image quality in positron emission tomography (PET), the attenuation correction technique based on the computed tomography (CT) data is important process. However, the artifact is caused by metal material during PET/CT scan, and the image quality is degraded. Therefore, the purpose of this study was to evaluate image quality according to with and without iterative metal artifact reduction (iMAR) algorithm using customized 3D printing phantom. Materials and Methods: The Hoffman and Derenzo phantoms were designed. To protect the gamma ray transmission and express the metal portion, lead substance was located to the surface. The SiPM based PET/CT was used for acquisition of PET images according to application with and without iMAR algorithm. The quantitative methods were used by signal to noise ratio (SNR), coefficient of variation (COV), and contrast to noise ratio (CNR). Results and Discussion: The results shows that the image quality applying iMAR algorithm was higher 1.15, 1.19, and 1.11 times than image quality without iMAR algorithm for SNR, COV, and CNR. Conclusion: In conclusion, the iMAR algorithm was useful for improvement of image quality by reducing the metal artifact lesion.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.27-32
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• 2008

Purpose: The evaluation of SUV (Standardized Uptake Values) for quantitative analysis in PET exam is the most significant. In PET exam, we make attenuation correction images by using $^{68}Ge$, $^{137}Cs$ or CT data. At this time, a distorted attenuation map affects quantitative analysis. After the exam using barium-sulfate and high density of barium contrast make attenuation map distorted. And then it brings bed influences on SUV. The aim of this study is to verify the relationship between high density barium-sulfate and SUV in PET exam. Materials and Methods By using $^{18}F$-FDG, we made barium-sulfate powder, density of 0, 1.5, 3, 5, 10 and 15% respectively and acquired PET and PET/CT images per each density. And we examined SUV variations from PET and PET/CT images according to differences of barium's density. Moreover, we finally calculated SUV causing variations in HU (Hounsfield Units) values to justify whether the differences of barium density bring any changes in PET/CT exam. Results: From PET images acquired from transmission scan with $^{68}Ge$, we got SUV figures from 6.46 to 6.8 in barium density between 0 to 15 percent. On the other hand, In PET images acquired from Tx scan that using CT, SUV was 6.77 to 23.73, derived from the same barium density. And CT HU values range from 29 to 2004. Conclusion: PET images from Tx data using $^{68}Ge$ weren't affected by barium density and had no differences in SUV. But in the PET/CT images using CT Tx data, there's considerable variations in HU and SUV values according to a difference of barium density in HU values. To perform a precise examination, barium sulfate should be removed from a human body before performing a PET exam.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.2
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• pp.55-64
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• 2017

Purpose Recently, with the spread of SPECT/CT, various image correction methods can be applied quickly and accurately, which enabled us to expect quantitative accuracy as well as image quality improvement. Among them, the Collimator Detector Response(CDR) recovery is a correction method aiming at resolution recovery by compensating the blurring effect generated from the distance between the detector and the object. The purpose of this study is to find out quantitative change depending on the change in detection distance in SPECT/CT images with CDR recovery applied. Materials and Methods In order to find out the error of acquisition count depending on the change of detection distance, we set the detection distance according to the obit type as X, Y axis radius 30cm for circular, X, Y axis radius 21cm, 10cm for non-circular and non-circular auto(=auto body contouring, ABC_spacing limit 1cm) and applied reconstruction methods by dividing them into Astonish(3D-OSEM with CDR recovery) and OSEM(w/o CDR recovery) to find out the difference in activity recovery depending on the use of CDR recovery. At this time, attenuation correction, scatter correction, and decay correction were applied to all images. For the quantitative evaluation, calibration scan(cylindrical phantom, $^{99m}TcO_4$ 123.3 MBq, water 9293 ml) was obtained for the purpose of calculating the calibration factor(CF). For the phantom scan, a 50 cc syringe was filled with 31 ml of water and a phantom image was obtained by setting $^{99m}TcO_4$ 123.3 MBq. We set the VOI(volume of interest) in the entire volume of the syringe in the phantom image to measure total counts for each condition and obtained the error of the measured value against true value set by setting CF to check the quantitative accuracy according to the correction. Results The calculated CF was 154.28 (Bq/ml/cps/ml) and the measured values against true values in each conditional image were analyzed to be circular 87.5%, non-circular 90.1%, ABC 91.3% and circular 93.6%, non-circular 93.6%, ABC 93.9% in OSEM and Astonish, respectively. The closer the detection distance, the higher the accuracy of OSEM, and Astonish showed almost similar values regardless of distance. The error was the largest in the OSEM circular(-13.5%) and the smallest in the Astonish ABC(-6.1%). Conclusion SPECT/CT images showed that when the distance compensation is made through the application of CDR recovery, the detection distance shows almost the same quantitative accuracy as the proximity detection even under the distant condition, and accurate correction is possible without being affected by the change in detection distance.

• The Korean Journal of Nuclear Medicine Technology
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• v.28 no.1
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• pp.23-29
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• 2024

Purpose: 99mTc-mebrofenin hepatobiliary scintigraphy (HBS) is an important and clinically useful diagnostic imaging study for detecting complications after liver transplantation. CT contrast agents due to their high atomic numbers, lead to a decrease in gamma ray count rates. This study investigated the impact of CT contrast agents on the uptake of 99mTc-mebrofenin in the liver. Materials and Methods: The quantitative HBS was performed on sixty-two liver transplantation patients (male:female=36:26), with a mean age of 59.4±6.4 years. Statistical comparison of hepatic uptake reduction ratio (HURR%) before and after the injection of CT contrast agents was performed using a paired t-test. Results: Hepatic uptake of the reduction ratio was 94.47±3.65% for the pre-CT contrast agents and 92.17±4.00% for the post-CT contrast agents. HURR% after CT contrast agent injection showed a statistically significant difference compared to before the injection (t=11.09, P<0.001). Conclusion: It will be necessary to pay attention when examining the HBS of patients with liver transplantation after the injection of CT contrast medium. It is advisable to schedule the examination on a different day to prevent residual contrast medium in the body from interfering with the quantitative evaluation of the nuclear medicine examination.

• Journal of the Korean Society of Radiology
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• v.12 no.5
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• pp.593-601
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• 2018

Recently in nuclear medicine, to improve diagnostic value, SUV, semi-quantitative indicator used in PET-CT, is adopted in SPECT-CT. Therefore, this research analyzed correlation of $SUV_{max}$ of two scanners through phantom test, and evaluated possibility of clinical application. Radiopharmaceuticals ($^{18}F$, $^{99m}Tc$) were injected with the ratios of 8:1 and 4:1, considering background radioactivity, into the phantom manufactured with 6 globes of different sizes, and, based on clinical protocol, positive phases were acquired with PET-CT and SPECT-CT scanners, and interesting areas were divided into ROI and VOI, and $SUV_{max}$ of them were measured, and analyzed. Tests found out no statistically significant difference in $SUV_{max}$ measured with two scanners (P>0.05). Thus, $SUV_{max}$ of PET-CT and SPECT-CT had a certain correlation within significant levels, and were evaluated as the same. Accordingly, it seems that $SUV_{max}$ quantitative analysis using SPECT-CT can provide significant diagnostic information as the case of PET-CT.

• Imaging Science in Dentistry
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• v.44 no.3
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• pp.177-183
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• 2014

Recent research in endodontics has highlighted the need for three-dimensional imaging in the clinical arena as well as in research. Three-dimensional imaging using computed tomography (CT) has been used in endodontics over the past decade. Three types of CT scans have been studied in endodontics, namely cone-beam CT, spiral CT, and peripheral quantitative CT. Contemporary endodontics places an emphasis on the use of cone-beam CT for an accurate diagnosis of parameters that cannot be visualized on a two-dimensional image. This review discusses the role of CT in endodontics, pertaining to its importance in the diagnosis of root canal anatomy, detection of periradicular lesions, diagnosis of trauma and resorption, presurgical assessment, and evaluation of the treatment outcome.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.808-816
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• 2021

Pulmonary emphysema is a cause of chronic obstructive pulmonary disease. Emphysema can be accurately diagnosed via CT. The severity of emphysema can be assessed using visual interpretation or quantitative analysis. Various studies on emphysema using deep learning have also been conducted. Although the classification of emphysema has proven clinically useful, there is a need to improve the reliability of the measurement.