APERTURE UNIT OF X-RAY CT DEVICE

摘要

PURPOSE:To improve precisions of the degree of parallelism of sectorial parallel beams and the slice thickness by providing a quadric crank chain having two lead plates as one opposed links and rotating and driving the other opposed links to obtain a prescribed slit width. CONSTITUTION:The quadric crank chain which has lead plates 11a and 11b as one opposed links and has connecting plates 12a and 12b of the same length as the other opposed links is constituted with pins 13a-14d. The center of the connecting plate 12a is fixed to an output shaft 14a of a pulse motor 14 fixed to an aperture unit case, and the center of the connecting plate 12b is supported rotatably by a pin 15 stuck to the aperture unit case. Tension springs 16a and 16b are stretched between pins 19a and 19b and pins 20a and 20b respectively in parallel with connecting plates 12a and 12b to eliminate play of links. A slit width (w) can be changed continuously by rotation of the shaft 14a. Thus, precision of the degree of parallelism of sectorial parallel beams and the slice thickness are improved.