CCD DETECTOR DEVELOPMENT FOR DIGITAL X-RAY MAMMOGRAPHY

A HIGH-RESOLUTION SCANNED-PROJECTION RADIOGRAPHY SYSTEM IS PROPOSED FOR DIGITAL MAMMOGRAPHIC APPLICATIONS. BY USING A WIDE, DYNAMIC-RANGE CCD DETECTOR, SOME OF THE CURRENT LIMITATIONS ENCOUNTERED IN CONVENTIONAL FILM-SCREEN MAMMOGRAPHY CAN BE AVOIDED. ONE-DIMENSIONAL, FANBEAM GEOMETRY PROVIDES VERY GOOD SCATTERED X-RAY REDUCTION. A TIME-DELAY-AND-INTEGRATE (TDI) MODE OF CCD IMAGING WITH A 2,048X96 ELEMENT CCD ARRAY PROVIDES THE OPPORTUNITY TO IMAGEWITHOUT THE EXCESSIVE POWER-LOADING OF X-RAY TUBES THAT WOULD BE REQUIRED WITH A 2,048X1 ARRAY. BY UTILIZING TDI CHARGE INTEGRATION WHILE THE DETECTOR IS SCANNED, EACH PROJECTION THROUGH STATIONARY ANATOMY IS AVERAGED OVER 96 EXPOSURES, THEREBY PROVIDING A SIGNIFICANT SIGNAL-TO-QUANTUMMOTTLE IMPROVEMENT OF APPROXIMATELY 10:1 WHEN COMPARED TO A 2,048X1 DETECTOR AT THE EQUIVALENT TUBE LOADING. DEVELOPMENTAL TASKS TO BE PERFORMED INCLUDE CONSTRUCTION OF A TDI-CCD X-RAY DETECTOR IN WHICH THE LIGHT OUTPUT OF AN X-RAY-INTENSIFYING SCREEN IS COUPLED BY MEANS OF A LENS TO THE CCD FOCAL PLANE, MEASUREMENT OF X-RAY SENSITIVITY, ASSESSMENT OF NOISE CHARACTERISTICS AND HOMOGENEITY OF THE X-RAY DETECTOR CONSTRUCTION OF A MOVING-SAMPLE X-RAY IMAGING SYSTEM BASED ON THE TDI DETECTOR, AND DETERMINATION OF THE OPTIMUM X-RAY SPECTRUM FOR DIGITAL MAMMOGRAPHIC IMAGING TASKS TO EVALUATE ITS CLINICAL POTENTIAL.