Abstract: In addition to a fixed collimator bore on the upper part of which a detec for gamma rays can be mounted, a lead plug or plate body has mostly conical bores in which angularly adjustable collimator tube bodies are seated. In one embodiment the lower part of the mostly conical bore is widened to provide a ball joint with an enlarged part of a collimator body which permits swiveling in any direction within the limits imposed by the walls of the conical part of the bore in the lead plug. In another embodiment intermediate rotary conical bodies are mounted in the shield plug and the collimator bodies either swivel about a horizontal axis that can be rotated by turning the intermediate body, or else the collimator body itself is a rotary cone frustum with an eccentric collimator bore for adjustment of the angle of inclination of the collimator orientation. The collimator bodies and, if used, the intermediate bodies, are made to contribute to the shielding against disturbing radiation.