MEASUREMENT OF COLLIMATOR HOLE ANGULATION AND CAMERA HEAD TILT FOR SLANT AND PARALLEL HOLE COLLIMATORS USED IN SPECT

  • 1 October 1987
    • journal article
    • research article
    • Vol. 28  (10) , 1592-1598
Abstract
Collimator hole angulation was measured at 16 locations in three collimators used in SPECT. The parallel hole collimator measured -0.1 .+-. -0.1 s.d. degrees in the X and -0.2 .+-. 0.1 s.d. degrees in the Y direction. One 30.degree. nominal slant hole collimator revealed a 0.1 .+-. 0.3 s.d. degrees angulation in X and 26.5 .+-. 1.1 s.d. degrees angulation in Y, which was unacceptable. The replacement collimator measured 0.0 .+-. 0.1 s.d. degrees in X and 29.6 .+-. 0.2 s.d. degrees in Y. Determination of collimator hole angulation is recommended as an acceptance test for SPECT systems. The net angle of tilt with respect to the orthogonal resulting from a particular collimator and camera head tilt was determined from summed projection images over 360.degree. of a point source placed off the axis of rotation. These measurements were sensitive within a 0.5.degree. tilt angle. The method is suggested as a routine quality control procedure to optimize camera head tile to a particular collimator. It may also reveal unexpected mechanical misalignments in the camera gantry.

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