| 摘要 |
In order to fix, inter alia, an optimum layer position the adjustment devices (M1 to M3) for the rotating unit (3) are designed such that the rotating unit (3) is adjustable in at least two starting positions (P1, P2) from which rays (S1, S2) are emitted by the radiation source (4) at different angles ( alpha , ss) relative to a reference plane (31), specifically starting at a point adjacent to the jaw and outside the latter up to the beginning of the penetration of the radiation into the jaw. A control unit (33) controls the drives (M1 to M3) for the adjustment of the rotating unit (3) in such a way that it is initially adjusted from the first starting position (P1) and then from the second starting position (P2) into a position (X) which corresponds in each case to the beginning of the penetration of the radiation into the jaw. Position transmitters (38) record the position of the rotating unit relative to a reference plane. A computing unit (36) in which variables (distances a to d, angles alpha and ss) determining the positions of the rotating unit are entered and processed in a computing operation initially gives a variable corresponding to the jaw width (B) as the result. This variable can then be used to determine further data such as the optimum layer position, etc. <IMAGE>
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