一、引言众所周知，CT机的扫描方式已经过了几代的更新，每一次的更新换代都将CT机带入一个全新的境地。最早的直线扫描方式的CT机、X射线为一直线射束，只能做头颅扫描，扫一层需时几分钟，扫描速度极慢，X线的利用率也极低；后来的直线加旋转扫描方式的CT机、X射线为一具有几 I. INTRODUCTION It is well-known that the scanning method of CT machines has been updated for several generations. Each update will bring the CT machine into a completely new situation. The earliest linear scanning CT machines and X-rays were straight lines and could only perform head scans. The scanning of one layer took a few minutes, the scanning speed was extremely slow, and the X-ray utilization rate was extremely low; the subsequent straight-line plus rotation Scanning CT machine, X-ray with a few