微型CT中X射线散射影响

Effects of X-ray scatter on micro-CT

为了评估了小动物锥束微型计算机层析图像(micro-CT)中低能X射线散射的大小和对系统成像结果的影响,该文引入了散射率(scatter-to-pri mary ratio,SPR)的概念。采用主射线终止法计算X射线散射率大小,并利用外推拟合法估测直径为0 mm阻挡物的散射值。用铅板制成的狭缝改变系统成像的锥角大小,讨论了锥束micro-CT中锥角大小与散射率的关系。直径40 mm的均匀树脂模型用来模拟小鼠,当锥角分别为0.247°和5.67°时,X射线散射率分别为4.78%和27.58%。讨论了散射对重建图像均一度和对比度的影响。

This study evaluates the magnitude and the effects of scatter of low kV X-ray in cone-beam micro CT （micro-computed tomography） system for small animals. The magnitude of scatter is based on scatter to-primary ratio （SPR） calculated using the beam stop method and estimated by polynormail-fitting extrapolation to 0 mm size stoppers. Lead foils with various slit widths were used to change the cone angle for the micro-CT imaging and its effect of the X-ray scattering. The standard phantom consisted of a uniform resin （40 mm diameter） representing a small mouse. The SPR at the center of the cone-beam system is 4.78% at the cone angle of 0. 247% and is 27. 58% at the cone angle of 5.67%. The effects of X-ray scattering on the reconstructed image uniformity and contrast ratio are also evaluated,