摘要
目的:设计应用于检测CT图像空间分辨力的实用方法及体模。方法:检测体模由两块纯有机玻璃中嵌入约0.1 mm厚的铝箔制成,扫描时使之与扫描面垂直,得到系统的冲击响应,即线扩展函数,经相干平均和傅立叶变换等步骤获得系统的调制传输函数,从而评价设备的空间分辨力。受检设备为单层面和多层面CT扫描仪各一台,设置不同扫描条件,共做4组实验。结果:调制传输函数曲线与所采用的扫描条件一致,截止频率与采用国际通用的CAPHAN 500体模测量的结果相当。结论:与线对法相比,通过测量线扩展函数计算调制传输函数来评价CT图像空间分辨力的方法减少了人工干预,结果准确、可靠。
Objective：To design a practical method and an attached phantom for testing the spatial resolution of CT scanners. Methods： A phantom made of acrylic and embedded with an aluminum foil of approximately 0, 1ram thick was used to simulate an ideal impulse input. The CT phantom was carefully set with the XY plane perpendicular to the foil, when it was scanned. Processing the impulse responses with the procedures of coherent averaging and Fourier transformation, the line spread function （LSF） and the modulation translation function （MTF） of the CT system were obtained and then the spatial resolution could be evaluated. Two CT scanners were tested with different parameters. Results： The curves of MTF were consistent with the corresponding scanning modes and techniques used,and the cutoff frequency was correlated to the results measured with a CAPHAN500 phantom. Conclusion：For the evaluation of the spatial resolution of CT images, it was more accurate and reliable, with less artificial interference, to use the method of measuring LSF and MTF in comparison with line pairs method.
出处
《放射学实践》
2006年第3期303-305,共3页
Radiologic Practice
