PHILIPS大孔径CT模拟机层敏感度曲线的测试研究

对Phihps AcQSim CT模拟机,采用头部螺旋扫描模式和CT质控体模,分别以螺距(pitch)=0.5、0.8、1.0、1.3、2.0,扫描层厚2mm(标称值)进行扫描和重建,测试和评价螺旋CT模拟机的层敏感度曲线(SSP)及半高宽(FWHM)。对于标称层厚2mm,不同pitch时测试得到的FWHM(有效层厚)均大于标称层厚。测试的SSP形状近似呈高斯分布形状。pitch的变化对SSP、有效层厚有一定影响。本研究结果有助于临床应用中优化CT扫描方案,从而为实现"三精"放射治疗提供技术支持。

Measurement of Slice Sensitivity Prof'de for PHILIPS Large Bore CT-Simulator

Using the CT technique of head mode,QA phantom was scanned with Philips AcQSim spiral CT.The slice sensitivity profiles (SSPs)and the full width at half maximum(FWHMs)were measured and evaluated with scanning slice width of 2ram at pitch=0.5, 0.8,1.0,1.3,2.0.The measured FWHM,i.e.effective slice width at different pitches were bigger than the normal slice width.The measured SSPs curves fitted Gaussian distribution.With the increasing of pitch,FWHMs increased accordingly.The variation of pitch has some effect on SSP,effective slice width for Philips AcQSim spiral CT system.The research is helpful to optimize CT scanning pro- tocol and provide technical support for the realization of radiotherapy of three precisions.