[Value of densitometry in the computer tomographic differentiation of paracranial space-occupying lesions. Experimental phantom studies and clinical evaluation].

Hardening of the beam is a major disturbing effect in densitometry close to the calotte. This phenomenon is demonstrated in a phantom, and its theoretical base is discussed. If possible sources of error are considered and reduced by means of appropriate measuring conditions, measurement of density will furnish useful additional data in CT examination. The value of CT densitometry is demonstrated via follow-up observations; after an operation of a glioma of the optic nerve, a child developed hygromas complicated by superinfection which subsequently became horny or calcified.