Wasserman H J
Department of Nuclear Medicine, Tygerberg Hospital, South Africa.
Nucl Med Commun. 1998 Nov;19(11):1089-97. doi: 10.1097/00006231-199811000-00009.
A method that has previously been described for rapid objective measurement of intrinsic gamma camera spatial resolution using statistical moments has been applied to images of a four-quadrant bar phantom acquired with various collimators. The full-width at half-maximum (FWHM) of the line spread function (LSF) and modulation transfer functions determined by the moments method was compared with those obtained directly from line spread functions. It was found that, for highest accuracy, the formulae originally described for intrinsic measurements have to be modified to take account of a more accurate description of the Fourier components of the input from a bar phantom. When this modification was applied, FWHM measurements agreed to within 4.0% with the LSF measurements in the range 4.5-7.2 mm if well-resolved images of bars wider than 3.0 mm were used. The method is simple to apply and since the coefficient of variation of these measurements was < 2.2%, it is well-suited for rapid objective routine monitoring of gamma camera spatial resolution. For modulation transfer functions > 0.2, bar sizes of 4.0 and 4.5 mm gave values within 4% of the LSF measurements, when the modified formula was applied, with coefficients of variation less than 4%.
一种先前已被描述的使用统计矩快速客观测量伽马相机固有空间分辨率的方法，已应用于用各种准直器采集的四象限条形模体的图像。将通过矩量法确定的线扩展函数（LSF）的半高全宽（FWHM）和调制传递函数与直接从线扩展函数获得的结果进行比较。结果发现，为了获得最高精度，最初描述的用于固有测量的公式必须进行修改，以考虑对条形模体输入的傅里叶分量进行更准确的描述。应用此修改后，如果使用宽度大于3.0 mm的条的清晰分辨图像，则FWHM测量值与4.5 - 7.2 mm范围内的LSF测量值在4.0%以内相符。该方法易于应用，并且由于这些测量的变异系数<2.2%，它非常适合于对伽马相机空间分辨率进行快速客观的常规监测。对于调制传递函数>0.2，当应用修改后的公式时，4.0和4.5 mm的条尺寸给出的值在LSF测量值的4%以内，变异系数小于4%。
