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Quality of shadowgraphic x-ray images

  • US 4,773,087 A
  • Filed: 04/14/1986
  • Issued: 09/20/1988
  • Est. Priority Date: 04/14/1986
  • Status: Expired due to Term
First Claim
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1. An x-ray machine comprising:

  • a source of an x-ray beam;

    a scanner means to move the beam relative to a patient;

    an imaging device which has means to receive x-rays which have been attenuated by the patient during a succession of imaging intervals to form an x-ray image of the patient;

    a feedback system for deriving pre-exposure measurements of x-rays attenuated by the patient during a succession of feedback intervals which alternate with said imaging intervals for a single image of the patient and for causing the radiation during the imaging intervals to be modulated as a function of respective pre-exposure measurements, said feedback system comprising an x-ray detector receiving x-rays attenuated by the patient during said feedback intervals and a circuit which modulates the intensity and hardness of the beam during said imaging intervals on the basis of the x-rays attenuated by the patient and received by the detector during respective feedback intervals previous to said imaging intervals.

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