• Journal of the Korean Society of Radiology
• /
• v.10 no.7
• /
• pp.503-510
• /
• 2016

Even though children are exposed to the same amount of radiation, their effective dose amount is higher than those of adults. Therefore, it is very important to reduce the amount of unnecessary radiation exposure because children have a higher radiosensitivity and a smaller body size than adults. In this study, the proposal to seek ways to reduce the amount of radiation is drawn by comparing and analyzing CT Dose Index(CTDI) on the pediatric head CT which was performed at the Busan regional hospitals, to the national diagnostic reference levels. For this, the pediatric head CT scan was conducted among the CT equipments that were installed in downtown Busan. From 2,043 children 10 years old or less who were referred to the pediatric head CT scan, targeting the 28 CT equipments in the 24 hospitals that transmit dose reports to PACS, were examined retrospectively. As a result, the average value of CTDIvol, computed tomography dose index (CTDI) of infant brain, across the hospital, was 31.18 mGy, with DLP of $444.73mGy{\cdot}cm$, which exceeded the diagnostic reference level. The lower the age, the more management is needed for radiation. However, the reality is that the CT examinations are being conducted with a dose that exceeds the reference level as the age of the aged is exceeded. For this purpose, the study seeks to determine the degree of doses of doses outside the diagnostic reference level and analyze the cause of the excess dose and devise measures to reduce the dose reduction.

• Korean Journal of Digital Imaging in Medicine
• /
• v.13 no.2
• /
• pp.63-69
• /
• 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 radiological science and technology
• /
• v.39 no.1
• /
• pp.71-79
• /
• 2016

The purpose of this study is computed tomography contrast agent at low concentrations and low tube voltage technique to evaluate the usefulness on the phantom image. By varying the degree of mixture by the contrast medium concentration it was inserted in phantom. It was taken by changing the tube voltage and tube current step by step, and to evaluate the dose and the CT value obtained from the phantom image. As a result, low-contrast, low tube voltage(300 mgI/ml, 100 kV) was reduced by an average 21%(CTDIvol; computed tomography dose indexvol) more standard condition(350 mgI/ml, 120 kV). SNR was increased at all depths of the phantom, respectively 1:10 and 1:20(by diluting a contrast agent and normal saline) 12.2(26%) 6.2(17%). CNR was increased at all depths of the phantom, respectively 1:10 and 1:20(by diluting a contrast agent and normal saline) 11.5(32%), 6.3(26%). Research work on the CT scan is necessary in a variety of studies on the low contrast concentration and low tube voltage techniques for dose reduction and reducing of side effects the contrast agent.

• Journal of Radiation Industry
• /
• v.11 no.3
• /
• pp.131-137
• /
• 2017

To compare the radiation dose and image noise of low dose computed tomography (CT) and high resolution CT using the fixed tube current technique and automatic tube current modulation (CARE Dose 4D). Chest CT and human anthropomorphic phantom were used the RPL (radiophotoluminescence) dosimeters. For image evaluation, standard deviation of mean CT attenuation coefficient and CT attenuation coefficient was measured using ROI analysis function. The effective dose was calculated using CTDIvol and DLP. CARE Dose 4D was reduced by 74.7% and HRCT by 64.4% compared to the fixed tube current technique in low dose CT of chest phantom. In CTDIvol and DLP, the dose of CARE Dose 4D was reduced by fixed tube current technique. For effective dose, CARE Dose 4D was reduced by 47% and HRCT by 46.9% compared to the fixed tube current method, and the dose of CARE Dose 4D was significantly different (p<.05). Noise in the image was higher than that in the fixed tube current technique. Noise difference in the image of CARE Dose 4D in low dose CT was significant (p<.05). The low radiation dose and the noise difference of the CARE Dose 4D were compared with the fixed tube current technique in low dose CT and HRCT using chest phantom. The radiation doses using CARE Dose 4D were in accordance with the national and international dose standards. CARE Dose 4D should be applied to low dose CT and HRCT for clinical examination.

• Journal of the Korea Convergence Society
• /
• v.9 no.12
• /
• pp.107-113
• /
• 2018

The purpose of this study was to evaluate the dose and image quality according to the rotation of the X-axis direction in the abdominal CT scan, and to find ways to reduce the exposure dose. The phantom was scanned by rotating in the X-axis direction at 0, 5, 10, and 15 degrees, respectively. The CTDIvol value, HU, noise, and signal-to-noise ratio were measured at each rotation. ANOVA analysis was performed using the SPSSWIN (ver 19.0) program. The radiation exposure dose was 5.44mGy, 5.70mGy, 5.98mGy and 6.38mGy at 0, 5, 10 and 15 degrees, respectively. HU, noise, and signal-to-noise ratio were not statistically significant. In the CT scan, if the patient is located in the isocenter of the gantry aperture and there is no rotation in the X-axis direction, the exposure dose is reduced.

• Journal of the Korean Society of Radiology
• /
• v.16 no.4
• /
• pp.387-394
• /
• 2022

120 kVp FBP reconstruction image standard by using raw data after scanning by changing tube voltage among the NECK CT protocols that are broad applied in clinical practice using a human phantom including thyroid gland The usefulness of the DLIR reconstruction technique was investigated. As a result, CTDIvol decreased when the DLIR reconstruction technique was applied, and in particular, the image quality obtained under the same standard scanning conditions at a lower dose for ASIR-V and DLIR reconstruction was reached than when FBP was applied at the same kVp In addition, as a result of SNR and CNR analysis, the DLIR reconstructed image was analyzed with high SNR and CNR values, and SSIM analysis, the SSIM index of the 100 kVp, DLIR reconstructed image was measured to be close to 1, and it was analyzed that the similarity of the reconstructed image to the original image was high (p>0.05). If the results of this study are used to supplement clinical image evaluation and further develop an algorithm applicable to various anatomical structures, it is thought that it will be useful for clinical application as it is possible to maintain the image quality while lowering the examination dose.

• Journal of radiological science and technology
• /
• v.38 no.1
• /
• pp.51-61
• /
• 2015

Computed tomography(CT) using radiation have potential risks. All medical radiographic examinations should require the justification of medical imaging examinations and optimization of the image quality and radiation exposure. The CT examination was higher radiation dose then general radiography. Especially pediatric CT examinations need to great caution of radiation risk. Because of pediatric patient was more sensitive of radiation exposure. Therefore, physician should consider the knowledge of CT radiation exposure indicator information for reduce a needless radiation exposure. This article was aim to understanding of CT exposure indicator, size-specific dose estimates by American Association of Physicists in Medicine (AAPM) report 204, XR 25 and understanding of CT dose reduction technique.

• Journal of radiological science and technology
• /
• v.41 no.5
• /
• pp.405-411
• /
• 2018

We will provide basic data on the evaluation of patient dose in terms of DECT quality control by comparing the equipment-provided dose with the measured dose according to the configuration method of the X-ray generator by the manufacturer of the dual-energy CT unit. For computed tomography (CT) equipment, Discovery 750HD, Aquilion ONE GENESIS Edition, and Somatom Definition Flash were used. The $CTDI_{vol}$ value was measured by inserting the Unfors Xi ion chamber into a 32 cm PMMA acryl Phantom. The results of estimated $CTDI_{vol}$ DECT and measured $CTDI_{vol}$ showed that the dose difference between DECT 80 + 140 kVp of G company was at least 0.51% and -1.90% max, and measured $CTDI_{vol}$ was slightly lower (p<0.05). The difference of 80 + 140 kVp of S company was the minimum of 5.84% and the maximum of 7.52% (p<0.05). The measured $CTDI_{vol}$ was less than estimated $CTDI_{vol}$. The C company's 80 + 135 kVp showed a difference of at least 7.58% and a maximum of 13.58% (P<0.05), and all of measured $CTDI_{vol}$ was less. The linearity of exposure dose for all DECT equipment was very linearly reflected with $R^2$ being 0.97 or above, and the measured dose of the ionization chamber was less than the predicted dose of the monitor.

• Journal of Biomedical Engineering Research
• /
• v.39 no.3
• /
• pp.116-123
• /
• 2018

This study is a model experimental study using a phantom to propose an optimized brain CT scan protocol that can reduce the radiation dose of a patient and remain quality of image. We investigate the CT scan parameters of brain CT in clinical medical institutions and to measure the important parameters that determine the quality of CT images. We used 52 multislice spiral CT (SOMATOM Definition AS+, Siemens Healthcare, Germany). The scan parameters were tube voltage (kVp), tube current (mAs), scan time, slice thickness, pitch, and scan field of view (SFOV) directly related to the patient's exposure dose. The CT dose indicators were CTDIvol and DLP. The CT images were obtained while increasing the imaging conditions constantly from the phantom limit value (Q1) to the maximum value (Q4) for AAPM CT performance evaluation. And statistics analyzed with Pearson's correlation coefficients. The result of tube voltage that the increase in tube voltage proportionally increases the variation range of the CT number. And similar results were obtained in the qualitative evaluation of the CT image compared to the tube voltage of 120 kVp, which was applied clinically at 100 kVp. Also, the scan conditions were appropriate in the tube current range of 250 mAs to 350 mAs when the tube voltage was 100 kVp. Therefore, by applying the proposed brain CT scanning parameters can be reduced the radiation dose of the patient while maintaining quality of image.

• Journal of radiological science and technology
• /
• v.38 no.2
• /
• pp.107-114
• /
• 2015

The purpose is reducing radiation dose while maintaining of image quality in liver dynamic CT(LDCT) scan, by protocols generally used and the tube voltage set at a low level protocol compared to the radiation dose and image quality. The target is body mass index, 18.5~24 patients out of 40 patients who underwent the ACT(abdominal CT). Group A(tube voltage : 120kVp, SAFIRE strength 1) of 20 people among 40 people, to apply the general abdominal CT scan protocol, group B(tube voltage : 100kVp, apply SAFIRE strength 0~5) was 20 people, set a lower tube voltage. Image quality evaluation was setting a region of interest(ROI) in the liver parenchyma, aorta, superior mesenteric artery (SMA), celiac trunk, visceral fat of arterial phase. In the ROI were compared by measuring the noise, signal to noise ratio(SNR), contrast to noise ratio(CNR), CT number. In addition, qualitative assessments to evaluate two people in the rich professional experience in Radiology by 0-3 points. We compared the total radiation dose, dose length product(DLP) and effective dose, volume computed tomography dose index(CTDIvol). The higher SAFIRE in the tube voltage 100 kVp, noise is reduced, CT number was increased. Thus, SNR and CNR was increased higher the SAFIRE step. Compared with the tube voltage 120kVp, noise, SNR, CNR was most similar in SAFIRE strength 2 and 3. Qualitative assessment SAFIRE strength 2 is the most common SAFIRE strength 2 the most common qualitative assessment, if the tube voltage of 100kVp when the quality of the images better evaluated was SAFIRE strength 1. Dose was reduced from 21.69%, in 100kVp than 120kVp. In the case of a relatively high BMI is not LDCT scan, When it is shipped from the factory tube voltage is set higher, unnecessary radiation exposure when considering the reality that is concerned, when according to the results of this study, set a lower tube voltage and adjust the SAFIRE strength to 1 or 2, the radiation without compromising image quality amount also is thought to be able to be reduced.