Multiple detector ring spiral scanner with relatively adjustable helical paths

摘要

A CT scanner (10) has an x-ray source (12) which transmits a plurality (N) of x-ray fans across an examination region (14) to a plurality of rings of radiation detectors (28). An adjustable septum (80) adjusts a gap between the fan beams and outer collimators (82) adjust the width of the fan beams such that the effective spacing and width are adjusted. The x-ray source rotates around the examination region as a subject support (32) moves longitudinally through the examination region such that the x-ray fans move along interleaved spiral trajectories. Radiation attenuation data from each of the x-ray fans is combined and reconstructed into a plurality of images along parallel slices orthogonal to the longitudinal axis. The spacing between the x-ray beams is adjusted relative to the effective pitch of the spirals such that the leading edges of the x-ray fans intersect a common transverse plane at 180 DEG /N angular intervals around the longitudinal axis.