• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.125-130
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• 2021

In the AAPM CT performance phantom, there is little data on the CT number of the effective atomic number and physical density corresponding to each peg and water of the CT number calibration insert. Therefore, the necessity of documentation was raised.The purpose of this study is to calculate the effective atomic number for each peg and water of the CT number calibration insert in the AAPM CT performance phantom, and to measure the CT number for the calculated effective atomic number and physical density for comparative analysis.In order to obtain CT number data on the effective atomic number and physical density of each peg and water from the CT number calibration insert of the AAPM CT performance phantom, the effective atomic number for each peg and water was first calculated. Then, CT slices were obtained by scanning the CT number calibration with a CT scanner. CT numbers were measured for each peg and water in the central CT slice. As a result, the CT numbers for the effective atomic number showed a nonlinear pattern of repeating the increase and decrease as the effective atomic number increased. In addition, the CT numbers for physical density showed a nonlinear pattern of repeating the increase and decrease as the physical density increased.

• Journal of the Korean Society of Radiology
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• v.16 no.5
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• pp.537-543
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• 2022

The purpose of this simulation study was to evaluate the possibility of pancreas detection through effective atomic number information using dual-energy computed tomography(CT). The effective atomic number of 10 tissue-equivalent materials were estimated through stoichiometric calibration. For stoichiometric calibration, HU values at low-energy (80 kV) and high-energy (140 kV) for 10 tissue-equivalent materials were used. Based on this method, the effective atomic number image of the tissue-equivalent material was extracted through an iterative algorithm. According to the results, the attenuation ratio in accordance with the effective atomic number was estimated to have an R² value of 0.9999, and the effective atomic number of Pancreas, Water, Liver, Blood, Spongiosa, and Cortical bone was overall within 1% accuracy compared to the theoretical value. Conventional pancreatic cancer examination uses a contrast medium, so there is a possibility of potential side effects of the contrast medium. In order to solve this problem, it is thought that it will be possible to contribute to an accurate and safe examination by extracting the effective atomic number using dual-energy CT without contrast enhancement. Based on this study, future research will be conducted on the detection of pancreatic cancer using the HU value of pancreatic cancer based on clinical images.