Abstract: A scintillation crystal module of the type having a crystal housed in a backcap which is closed off by a glass window and sealed by an internal seal located between the window and the backcap is modified to include an external seal. The external seal is of moisture-impervious material and is attached to the outer surface of the backcap and the window and bridges over the boundary therebetween. The external seal may be made of an epoxy polyamid or a blocked urethane epoxy copolymer. The outer surface of the module may be sandblasted before the external seal is attached to the module, as by casting the adhesive in a suitable mold.

Abstract: An arrangement for determining the planar contour of an object including a plurality of light emitters and detectors positioned in a circular planar array. The circular array surrounds the object whose planar contour is being determined. The light emitters are sequentially energized and the resulting signals from the light detectors are utilized for determining the object's planar contour.