双探头符合成像系统的分辨率及其影响因素

Dual-head coincidence imaging resolution and influence factors

研究双探头符合成像系统的分辨率及其影响因素。采用Hawkeye双探头符合成像设备,对Toshiba椭圆柱分辨率模型成像。用X线透射扫描进行衰减校正,在不同的活度下做18次扫描。OS-EM算法选择4种后滤波截止频率重建图像。计算线源横断层面上扩展函数的半高宽(FWHM)。在视野中活度较低时(<101.00MBq),FWHM基本不随活度变化;但在较高的活度区,FWHM随视野中活度的增加而缓慢增加;在视野中心至横向12cm范围内,视野中心区径向FWHMx最大,越靠边缘越小,而切向FWHMy基本不随位置变化;FWHM随重建算法中后滤波截止频率的增加而减小。结论是视野中的总活度、位置及重建算法均影响双探头符合成像系统的分辨率。

The dual-head coincidence imaging resolution and its influence factors were investigated. Using G. E, Hawkeye dual-head coincidence detection equipment Toshiba elliptic cylinder resolution phantom was imaged. Attenuation correction was performed with X-ray transmission scan. Eighteen emission scans were performed at different radioactivity in the field of view. The images were reconstructed with 4 reconstruction algorithms. The full width at half maximum （FWHM） of the line resource spread function in transaxial slices was calculated. The FWHM decreased with decreasing radioactivity in the field of view in the range of higher activity. It didn＇t decreased in the range of lower activity （101. 00-12. 79 MBq）. At the same radioactivity the FWHM decreased with increasing cutoff frequency of filter; for the line resources distributed in horizontal direction, the horizontal FWHMx decreased with increasing distance from the center of field, while the vertical FWHM, didn＇t varied with the distance. The radioactivity in field of view, reconstruction algorithm and the position in the field of view can influence the dual-head coincidence imaging system resolution.