星卡像第二模糊带的应用探究

The application of the second fuzzy zone in star testing card X-ray image

目的星卡测量X线管焦点原理公式表明星卡像其他模糊带有其物理意义,基于此,笔者推导出含有模糊带信息的修正公式F=aZa/(M-1)(a表示第a模糊带,Za表示星卡像第a模糊带的直径),实验探究可测量第二模糊带的利用价值。方法应用1°星卡、2°星卡测量X线管等效焦点,分别测得星卡像第一模糊带Z1、第二模糊带Z2,带入修正公式求出等效焦点的值,进行比较分析。结果由1°星卡、2°星卡和第一模糊带Z1、第二模糊带Z2对同一X线管焦点测得的值在误差范围内相等。结论①由星卡像第一模糊带、第二模糊带均可以求出等效焦点的大小;②一定条件下,测量X线管焦点实验,1°星卡、2°星卡可以替换使用。

Objective：The principle and calculation formula of star testing card experiment measuring X-ray tube focus indicate that the second fuzzy zone has its physical meaning. Based on it , the author deduced the correctional formula with fuzzy zone information F =aZa/（M - 1） （ a shows the a＇th fuzzy zone, Za shows the a＇th fuzzy zone diameter on star card image ） , to explore the availability of the second fuzzy zone. Methods： In the experiment with 1 ° star card and 2 ° star car to measure the first fuzzy zone, the second fuzzy zone respectively and to calculate the equivalent focus respectively. Results： These datas are approximately equal by 1 ° star card, 2 ° star card ,the first conditions, 1 ° star card and 2 ° star car are alternatives.