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| Effect of different water phantom diameters and reconstruction slice thicknesses on CT image noise |
| ZHAO Xipeng1, XU Hui1, HUANG Zhuo1, YUE Baorong1, NIU Yantao2 |
1. Key Laboratory of Radiological Protection and Nuclear Emergency, China CDC, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, BeiJing 100088 China;
2. Beijing Tongren Hospital, CMU |
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Abstract Objective To study the influence of different water phantom diameters, reconstruction slice thicknesses and doses on CT image noise, discuss the reasonable diameter range of the water phantom in the CT quality control testing, and provide data to improve the standard of CT quality control testing in China.Methods The axial scanning mode of the CT of Revolution type produced by GE company was used. Under the conditions of different doses of CTDIW 30.20 mGy (120 kV, 200 mAs) and 49.82 mGy (120 kV, 330 mAs), and different reconstruction slice thicknesses of 5 mm and 10 mm, the water phantom with the diameters of 16, 18, 20, 22 and 24 cm was scanned and its CT values and image noises were measured. The differences of the image noises were compared under different water phantom diameters, thicknesses and doses.Results The value of image noise amplified with the increase of the diameter of the water phantom, and decreased with the increase of the dose. The noise values with the water phantom diameters of 24 cm and 22 cm exceeded the existing testing standard. The noise decreased with the increase of the thickness of the slice thickness.Conclusion The measurement results of image noise are related to factors such as the dose, the diameter of the water phantom, the reconstruction thickness, etc. In the noise measurement of CT quality control testing, the dose, slice thickness, and the size of the water phantom are required to be selected. The results show that the range between 18 cm and 22 cm may be a reasonable value for the diameter of water phantom on a dose of close to 50 mGy.
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Received: 07 September 2018
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