Error analysis on the measurement of spread function of radiography system by step method

After expatiating upon the principle of the measurement of spread function of radiography system by method of step, the errors caused by this method are analyzed. The different degrees on measurement caused by different factors (such as the intersectant degree between the axis and the edge of the step, distance between the axis and the step and the width of the step) are compared in detail. The directive principles on experiment set up for measurement of system SF are derived. Something which may be paid attentions to while carrying out the experiment are also pointed out.