• Korean Journal of Digital Imaging in Medicine
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• v.13 no.2
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• pp.63-69
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• 2011

Table strapis patient fixture for securing the patient movements and falls. if it designed to measure the abdominal circumference and used as an indicator of dose selection at CT scan. it will prevent the overexposure of dose without degradation of image quality and efficiently manage dose of each type of body to technician to deal with CT. First, in order to compare the dose used in CT image and qualitative characteristics. reference image is obtained by examining the abdominal phantom in same conditions with the hospital 120 kVp, 200 mAs, D-Dom (Dynamic Dose Of Modulation). SNR, PSNR, RMSE, MAE, CTDIvol of CT images are compared with reference image. for comparing with reference image, the image that Umbilicus level image of Abdomen CT is stored in the PACS were used. For comparison, the top 12 o'clock portion of the air drawn from the same ROI was measured. CTDIvol, mAs, etc. In order to analyze the characteristics of the image, by measuring the length of the umbilicus circumference, pattern of the dose was analyzed. by using the analyzed perimeter and dose information, To be identified visually, fixed band that scale marked were produced. Use them, If the length of circumference of less than 60 cm 100 mAs, Case of 61~80 cm 120 mAs, Case of 80~100 cm 150 mAs, more than 100 cm 200 mAs, dose selection based on the perimeter, the image was applied. by compare analyzed with the Reference Image, image quality was assessed. by compare with existing tests that equally 200 mAs applied, How much was confirmed that the dose reduction. 1. Depending on the Abdominal circumference, the average PSNR(dB) of the image that differently dose applied was 45.794. 2. Comparing with existing test. the dose of scan that adjusted the mAs depending on the circumference was decreased about 40%. SNR and PSNR of the image that obtained by adjusting the standard mAs based on dose modulation were not much different. Therefore, By choosing a low mAs. dose reduction can be obtained. and the dose selection method that measured Abdominal circumference using a fixed band can protect the overexposure and uniformly apply dose of each type of body to technician to deal with CT.

• Journal of the Korean Society of Radiology
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• v.11 no.3
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• pp.109-115
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• 2017

The purpose of this study was to evaluate the clinical efficacy of 128 MDCT (multi-detector computed tomography) for reducing the CareDose 4D dose and comparing the image quality with the fixed tube current technique. For this purpose, we conducted the phantom and clinical studies to evaluate the exposure dose and image of the subject before and after applying the CareDose 4D system in abdominal examination using 128 MDCT. In the phantom study, ROI (Region of interest) was located at the center, 3, 6, 9, 12 o'clock, into two groups: group A without CareDose 4D and Group B applied were measured. In the clinical study, ROI was located at the liver 8 segments, divided into two groups too. The measured items were CT number, noise, and dose length product (DLP) dose. The result of CTDIvol (CT Dose Index volume) measurements in phantom and clinical studies were lower than those before CareDose 4D application, and dose and effective dose were also measured lower (p<.05). There was no difference in CT number before and after application (p>.05). In conclusion, using CareDose 4D, we can obtain optimal image information without deteriorating image quality while reducing patient dose.

• Progress in Medical Physics
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• v.17 no.4
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• pp.207-211
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• 2006

The advent of kV cone-beam computed tomography (CBCT) integrated with a linear accelerator allows for more accurate Image-guided radiotherapy (IGRT). IGRT is the technique that corrects target displacement based on internal body information. To do this, the CBCT Image set is acquired just before the beam is delivered and registered with the simulation CT Image set. In this study, we compare the registration results according to the CBCT's reconstruction quality (either high or medium). A total of 56 CBCT projection data from 6 patients were analyzed. The translation vector differences were within 1 mm in all but 3 cases. For rotation displacement difference, components of all three axes were considered and 3 out of 168 ($56{\times}3$ axes) cases showed more than lo of rotation differences.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.36-40
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• 2011

Purpose: $^{18}F$-FDG injected dose to the patient is quite different between the recommended dose from manufacturer and the actual dose applied to each of hospitals. injection of inappropriate $^{18}F$-FDG dose may not only increase the exposed dose to patients but also reduce the image quality. we thus evaluated the proper $^{18}F$-FDG injected dose to decrease the exposed dose to patients considering the image quality. Materials And Methods: NEMA Nu2-1994 phantom was filled with $^{18}F$-FDG increasing hot cylinder radioactivity concentration to 1, 3, 5, 7, 9 MBq/kg based on the ratio of 4:1 between the hot cylinder and background activity. after completing the transmission scan using ct, emission scan was acquired in 3D mode for 2 minutes 30 seconds/bed. ROI was set up on hot cylinder and background radioactivity region. after measuring $SUV_{max}$ those regions, then analyzed SNR at the points. clinical experiment has been conducted the object of patients who have came to smc from november 2009 to august 2010, 97 patients without having a hepatic lesions were selected. ROI was set up in the liver and thigh area. after measuring $SUV_{max}$, the image quality was compared following the injected dose. Results: in phantom study, as the injected radioactivity concentration per unit mass was 1, 3, 5, 7, 9 MBq/kg, $SUV_{max}$ was 23.1, 24.1, 24.3, 22.8, 23.6 and SNR was shown 0.48, 0.54, 0.56, 0.55, 0.55. according to increment of the injected dose, $SUV_{max}$ and SNR was increased under 5 MBq/kg but they were decreased over 7 MBq/kg. in case of clinical experiment, as increased the injected radioactivity concentration per unit mass was 4.72, 5.34, 6.16, 7.41, 8.68 MBq/kg, $SUV_{max}$ was 2.68, 2.67, 2.26, 1.88, 1.95 and SNR was shown 0.52, 0.53, 0.46, 0.46, 0.44. if the injected dose exceeds 5 MBq/kg, showed a decrease pattern as phantom study. Conclusion: increasing $^{18}F$-FDG injected dose considered patient's body weight improve image quality within a certain range. if it exceeds the range, it can be reduced image quality due to random and scatter coincidences. this study indicates that the optimal injected dose was 5 MBq/kg per unit mass the injected radioactivity concentration in 3d wb pet/ct.

• Journal of International Society for Simulation Surgery
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• v.2 no.1
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• pp.43-45
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• 2015

Recent progress on CT such as multi-detector row CT, oral contrast agents and multiplanar reconstruction have markedly improved the image quality as well as diagnostic performance of gastric cancer. Multiplanar reformatted images at predetermined orientations can be easily performed and embedded into routine CT protocol without increasing medical expense or labor. Currently, many institutions have adopted routine multiplanar reformatted protocols and therefore knowledge on them can improve the diagnostic accuracy of gastric cancer.

• Progress in Medical Physics
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• v.23 no.4
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• pp.292-302
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• 2012

The patient dose in advanced radiotherapy techniques is an important issue. These methods should be evaluated to reduce the dose in diagnostic imaging for radiotherapy. Especially, the Computed Tomography in radiotherapy has been used widely; hence the CT was evaluated for dose and image in this study. The evaluations for dose and image were done in equal condition due to compare the dose and image simultaneously. Furthermore, the possibility of dose and image evaluations by using the Monte Carlo simulation MCNPX was confirmed. We made the iterative reconstruction for low dose CT image to elevate image quality with Maximum Likelihood Expectation Maximization; MLEM. The system we developed is expected to be used not only to reduce the patient dose in radiotherapy, also to evaluate the overall factors of image modalities in industrial research.

• Imaging Science in Dentistry
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• v.49 no.2
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• pp.139-151
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• 2019

Purpose: This study was performed to investigate the effect of exposure parameters on image quality obtained using a cone-beam computed tomography (CBCT) scanner and the relationship between physical factors and clinical image quality depending on the diagnostic task. Materials and Methods: CBCT images of a SedentexCT IQ phantom and a real skull phantom were obtained under different combinations of tube voltage and tube current (Alphard 3030 CBCT scanner, 78-90 kVp and 2-8 mA). The images obtained using a SedentexCT IQ phantom were analyzed technically, and the physical factors of image noise, contrast resolution, spatial resolution, and metal artifacts were measured. The images obtained using a real skull phantom were evaluated for each diagnostic task by 6 oral and maxillofacial radiologists, and each setting was classified as acceptable or unacceptable based on those evaluations. A statistical analysis of the relationships of exposure parameters and physical factors with observer scores was conducted. Results: For periapical diagnosis and implant planning, the tube current of the acceptable images was significantly higher than that of the unacceptable images. Image noise, the contrast-to-noise ratio (CNR), the line pair chart on the Z axis, and modulation transfer function (MTF) values showed statistically significant differences between the acceptable and unacceptable image groups. The cut-off values obtained using receiver operating characteristic curves for CNR and MTF 10 were useful for determining acceptability. Conclusion: Tube current had a major influence on clinical image quality. CNR and MTF 10 were useful physical factors that showed significantly associations with clinical image quality.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.801-808
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• 2023

In order to minimize radiation exposure and secure diagnostic value images during CT examination of the head of children, the usefulness of volume axial mode is evaluated through comparison and analysis of exposure dose and images of volume axial mode, high pitch mode, and helical mode. Image evaluation and dose evaluation were performed in CT high pitch mode, helical mode, and volume axial mode for infants under the age of 1 according to the voltages of 70, 80, and 100 kVp tubes. The image evaluation was conducted by comparing image quality by setting ROI for each image, calculating SNR and CNR, using ONE-WAY (ANOVA) to evaluated statistical significance, and cross-examining the dose evaluation using DLP values displayed in the Dose Report. When inspected using volume axial mode, DLP values were generally low, and SNR and CNR values differed by ROI and kVp. When volume axial mode evaluated the quality of the image compared to other scan modes, the difference is not uniform. For the reason, certain modes are not considered excellent, but the exposure dose was reduced the most in terms of dose. In addition, the point that the volume axial mode can be examined at its original location, short scanning time and needless of table movement is useful for CT tests for children under 1 year of age with high radiation sensitivity.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.111-120
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• 2020

Research should be actively conducted for the ability of X-ray equipment and Retrospective image analysis of X-ray equipment used in hospitals. Retrospective image analysis of X-ray machines, CT and MRI of radiology and medical equipment has been actively conducted. However, image quality measurement using angiography equipment of angiography room is mostly measured with phantom, and image quality measurement on image after being taken by actual patient is insufficient and researches on accurate image quality measurement method are remarkable. It is in short supply. Therefore, through this study, the researcher devised a method to measure the image quality of the acquired image after coronary angiography, and to provide a high quality image to the operator. The equipment and programs used were angiographic examination equipment (Axiom Artis Zee Ceiling) and Image J program. Subjects were images automatically saved in PACS program after coronary angiography.For image quality measurement, selected the AP Caudal 30° image that show the LCA vessel well and the LAO 30° image that show the RCA vessel well during the coronary angiography. In order to measure the background and ROI of the selected image by selecting an image, a criterion on how to find and measure a section where the overlap of the shadow, such as blood vessel, liver and lung is minimized, is presented. In conclusion, there is no exact standard for analyzing an image quality measurement method of angiography image. Therefore, in order to provide quality images to the practistioners, not only the technicians of the equipment but also the users who actually use them should become researchers and conduct research on image quality measurement in various ways. Thus, it is expected to provide excellent images to patients.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.425-431
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• 2014

The purpose of this study is to analyze dose comparison and image quality evaluation according to Volume and Helical mode using ATOM Phantom. It is to actively use the Volume mode in pediatric CT examinations. There was no significant difference with Helical and Volume in the value of Noise, HU, SNR(p>0.05). All dose values was no statistical difference(p>0.05). In the value of DLP and effective dose by part, Volume mode was measured lower than Helical mode. For qualitative analysis, by scan parameter helical mode showed respectively 2.6, 3.3, 4.36 and Volume mode indicated 2.8, 3.64, 4.44 point. Image evaluation for the follow-up, Helical mode and Volume mode were respectively 3.8 and 3.83. In fact, There was no significant difference. In CT scans in children under 5 years, because 640-MDCT Volume scan dose compared with Helical mode is lower and there is no significant difference with two modes in the image quality, 640-MDCT Volume scan is thought to be useful for pediatric CT scans.