Abstract

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Author(s):: SHI Feiyue1; BAI Zhenglu2; QIN Hang2; QINWei1; LIN Qiang2; 1. Radiation Therapy Center, Nanjing First Hospital, Nanjing Medical University, Nanjing 210006, China; 2. Department of Medical Equipment, Nanjing First Hospital, Nanjing Medical University, Nanjing 210006, China

Keywords:: Keywords: CT simulator; image uniformity; tube voltage; long-term stability

Abstract:: Abstract: Objective To analyze the data from routine quality assurance (QA) measurement using water phantom and assess the long-term stability of image uniformity for a SIEMENS Sensation Open CT simulator. Methods The SIEMENS Sensation Open CT simulator was tested monthly using a water phantom and Daily Quality Check program. The CT images under the nominal tube voltages of 120 and 140 kV were obtained. Then the values of image uniformity were obtained by manual delineation and calculation. Finally, statistical analysis and comparative study were conducted on the test data obtained between March 2017 and February 2018. Results Under the nominal tube voltage of 120 kV, the values of image uniformity for the first to sixth slices, with a slice thickness of 4.8 mm, were (2.5±0.4), (2.8±0.6), (2.2±0.2), (1.5±0.7), (1.4±0.4) and (1.0±0.3) HU, respectively; and under the nominal tube voltage of 140 kV, the corresponding values were (2.0±0.2), (3.0±0.4), (1.5±0.5), (0.7±0.4), (0.5± 0.2) and (0.7±0.5) HU, respectively. In the 12 months, all the values of image uniformity were within 4 HU and only had little changes. Conclusion In a time period of 12 months, the image uniformity for SIEMENS CT simulator is relatively stable and meets the requirements for application. The slice position is one of the factors affecting the image uniformity.