TIM HUNTER, MD
Radiology at Campbell Ave, Tucson, AZ

5142557, Aug 25, 1992

Dec 21, 1990

7/633212

Emre Toker - Tucson AZ
Tim B. Hunter - Tucson AZ
Hans Roehrig - Tucson AZ

Photometrics Ltd. - Tucson AZ

A61B 604

378 37

A system for locating a region of varying density in biological tissue such as a breast includes a controlled x-ray source for directing x-rays through the breast, a phosphor screen positioned to receive x-rays exiting from the tissue and producing light in response thereto, a cooled, slow scan CCD camera, a variable magnification optical system positioned to receive light emitted by the phosphor screen and directing it to the cooled, slow scan CCD camera, a high resolution monitor, and a control system receiving signals from the cooled, slow scan CCD camera and digitizing the signals to produce digital data representative of the densities of various locations of the tissue. The control system includes a processor operated to determine a signal-to-noise ratio of light received by the cooled, slow scan CCD camera from the variable magnification optical system and to control the intensity of x-rays in response to the signal-to-noise ratio to determine locations of the object at which the corresponding densities exceed a certain level. The addresses of such locations are stored. The variable magnification optical system is controlled to focus and enlarge "digitally marked" locations of the object so images thereof substantially fill a screen of the monitor.