不同滤波函数和截止频率PET重建图像的结果比较

The Study of Reconstructed PET Images with Different Filter and Cutoff Frequency

目的:探求不同滤波函数和截止频率对PET 重建图像的影响,以获得适合临床各项检查的最佳滤波条件。材料和方法:PET 质控模型。用PET 对其进行常规采集,以不同滤波条件重建图像后进行比较。结果:冷区图像重建,当fc 相同时Hann 和Ham m 的比值优于其它滤波函数。比值优劣次序为Ham m 、Hann、Parzen 、Butterworth 和Butterworth2 。重建图像的噪声高低排序为:Ham m 、Hann 、Buterworth、Parzen 和Butterworth2 。相同滤波函数随fc 增高,高频噪声增加。热区图像的FWHM 随fc 减小而增大。排列为:Ham m 、Butterworth 、Hann 、Parzen 和Butterworth2 。周边圆柱的FWHM 比中心圆柱的大,差值最小的是Butterworth 。结论:(1) 重建脑断层图像,建议采用Ham m 或Hann ,fc = 0-3～0-4 或Butterworth ,fc= 0-4 ～0-5 。(2) 热区图像可适当提高fc,以提高分辨力。(3) 计算热区实际大小时可用FWHM估算,对直径1cm 的热区,Ham m 和Hann 在fc= 0-3 时,Butterworth 在fc= 0-2 时FWHM 接近实际大小。

Purpose:We studied the effect of different filter and fc on PET reconstructed image in order to find proper factors for clinical application.Material and Method:The quality control phantom of PET consisted of 6 solid inserts and 6 hollow one was used for image comparison with different filter and fc after routing acquisition and image reconstruction.Result:For the cold column image with same fc, Hann and Hamm was superior to other filter.The other filters were lined in order of Parzen, Butterworth and Butterworth2.Image noise is in order of Hamm, Hann, Butterworth, Parzen and Butterworth2 and the higher fc, the higher image noise.The FWHM of hot column with different filter and fc increases as the fc value decreases.Using same filter the outer FWHM is larger than the middle one, whereas the minimum deviation between them is Butterworth.Conclusion:1.For brain imaging, which demand high resolution, lower noise to observe tiny structure, we suggest Hamm and Hann, with fc 0 3, 0 4 or Butterworth with fc 0 4,0 5.2.For the hot image with low background increase of fc may enhance resolution.3.The size of hot area measured with hann, Hamm with fc 0 3 and Butterworth with fc 0 2 will close to the real one.