The terms "ultrasonic radiation" and "ultrasound" are employed interchangeably in this specification to designate pressure-rarefaction waves differing from sound waves in exhibiting higher frequencies and shorter wavelengths. The term "ultrasonic exposure" is employed to designate exposure to ultrasonic radiation. The production of visible images by means of ultrasonic radiation is referred to in the art as "ultrasonoscopy". The production of a visible record by means of ultrasonic radiation is referred to as "ultrasonography". The instruments for producing ultrasonoscopic images are designated "ultrasonoscopes", and the ultrasonoscopes which produce ultrasonographic images are referred to as "sonographic cameras". Elements which form visible images of ultrasonic radiation patterns as a result of being ultrasonically exposed in a sonographic camera are referred to as "ultrasonographic elements". Instruments which are capable of permitting ultrasonographic elements to be concurrently exposed in different areas to different intensities of ultrasound are referred to as "sonographic sensitometers".
The definition of terms as here presented is believed to be generally consistent with the use of these terms in the art. Specifically, most of these terms are suggested by P. J. Ernst in the Journal of the Accoustical Society of America, Vol. 22, No. 1, in an article entitled "Ultrasonography", pp. 80-83, January 1951.
In Belgian Pat. No. 864,089, dated Aug. 17, 1978, there is disclosed a process for imagewise ultrasonically exposing a silver halide photographic element. In one form this process calls for immersing a silver halide photographic element in a transport liquid, such as a polar solvent, preferably water or an aqueous solution, and imagewise ultrasonically exposing the element to ultrasound. Either during or after ultrasound exposure the photographic element is exposed to light. The element is then photographically processed in a conventional way, and an ultrasonographic image is produced for viewing. Since the photographic element forms an ultrasonographic image, it is by definition an ultrasonographic element. It is generally preferred to allow ultrasonographic elements a brief period of contact with the transport liquid prior to ultrasonic exposure, and in some forms it is preferred to delay light exposure for a few seconds following ultrasound exposure.
In commonly assigned, copending patent application titled ULTRASOUND IMAGING OF INTERNALLY FOGGED SILVER HALIDE ELEMENTS, Ser. No. 3,571, filed Jan. 15, 1979, there are disclosed internally fogged silver halide emulsion layer containing elements useful a ultrasonographic elements. The process of ultrasonographic exposure disclosed therein differs from that of Belgian Pat. No. 864,089 in that no light exposure step is employed during or after ultrasound exposure in order to produce a viewable ultrasonographic image.
In commonly assigned, copending patent application titled ULTRASONIC IMAGING WITH CATALYTIC ELEMENTS, Ser. No. 8,910, filed Feb. 2, 1979, ultrasonographic elements are disclosed containing a catalyst layer. Ultrasonic exposure can be undertaken while the ultrasonographic element is in contact with a transport liquid containing a catalyst poison. Light exposure is not required for imaging.
In forming ultrasonographic images as described above, ultrasound which has passed through the ultrasonographic element being exposed can be reflected back to the element and result in nonuniformities in background areas and/or in loss of image definition. Further, the ultrasonographic elements are very susceptible to image degradation when an interval exists between ultrasound exposure and formation of a developable latent image. During the interval between sound and light exposures, for example, care must be exercised to avoid disturbances in the transport liquid. Still further, the composition of the transport liquid can vary in the course of sequential imaging due to diffusion into or out of the ultrasonographic elements.