Gray scale performance of displays for dynamic ultrasound imaging.

Methods used to convert the output of diagnostic ultrasound dynamic imaging systems to television format are reviewed. The gray scale characteristics of a large-screen direct display are compared with the transfer through a display monitor-television camera-television monitor chain. Available direct display devices have distinct performance limitations in this application and the transfer linearity and dynamic range of the television converter described are objectively superior. This confirmed a subjective preference of system users to view the TV display.

State-of-the-art in two-dimensional ultrasonic transducer array technology.

Attention is given to means of sensing ultrasonic energy distributions over an area. Under the restraints appropiate to real-time imaging of deep body organs, piezoelectric arrays offer the most promising method. Adaptation of integrated circuit techniques to array assembly permits very large arrays of small elements to be batch fabricated. Further, special semiconductor switching devices specifically designed for addressing the array have been produced and applied. These permit both the passage of weak received signals and the application of voltage and current levels sufficient for transmission without significant disturbance of the basic piezoelectric element properties. Emphasis is placed on the complete data acquisition, processing, and display flexibility that arises from an array capability. Operation becomes possible in any of the presently used A or time motion (TM), in real time B or C scan, or in novel scan patterns adapted to specific organs. Further development with acoustic and electronic focusing, taking advantage of the unique possibilities obtained with the bidirectional array structure, is discussed.