Patent ID: 7209537

Claim:
A tomography apparatus comprising: an acquisition system adapted to interact with a subject to acquire projections of a region of the subject, said acquisition system comprising an x-ray radiator that emits x-rays with an x-ray dose predetermined by a voltage supplied to the x-ray radiator, a current supplied to the x-ray radiator, and an exposure time during which the x-ray radiator emits said x-rays; a first control unit connected to the x-ray radiator that alternatingly adjusts said voltage between a first voltage value for acquisition of high-energy projections and a second voltage value, differing from said first voltage value, for acquisition of low-energy projections; a second control unit connected to said x-ray radiator that alternatingly adjusts a further control variable for operating said x-ray radiator between a first control value associated with said first voltage value and a second control value, differing from said first control value, associated with said second voltage value; and an adjustment device connected to said first control unit and to said second control unit that adjusts said first control value dependent on said first voltage value and adjusts said second control value dependent on said second voltage value to cause said x-rays emitted by said x-ray radiator to have a substantially equal x-ray dose during acquisition of said high energy projections and during acquisition of said low energy projections.