Lumisys, Inc.

Resonex, Inc.

Arthur J Lim

Craig H Barratt

Michael H Buonocore

A method of ascertaining imaging quality in a computed radiography (CR) system includes providing a substrate having fluorescent test pattern disposed thereon. The substrate is disposed in place of the standard storage-phosphor screen and scanned as if reading out a storage screen. The detected signals form a read-out image which is then compared against the test pattern to judge image quality.

Apparatus and method for determining imaging quality in a computed radiography system

A wideband amplifier which employs a plurality of cascaded logarithmic amplifier stages under the control of a digital signal processor which nulls offset voltages. In one aspect of the invention, the digital signal processor controls switches, one switch associated with each amplifier stage for determining an appropriate offset voltage and producing a counterbalancing signal. In another aspect of the invention the amplifier includes two potentiometers or variable signal devices which can set the overall input signal level and set the ratio of maximum to minimum of the input signal level, respectively, to desired levels. In a third aspect of the invention, a lookup table is associated with the digital signal processor for storing correction factors to be applied to digitized values in order to produce a final result which is corrected for variations in the amplifier characteristic from true logarithmic.

Wideband amplifier with logarithmic output characteristic

In an improved NMR imaging method for forming images of a subject by determining the relative densities of nuclei within the subject, three orthogonal gradient fields are generated by digitally storing three gradient waveforms for each orthogonal direction, with each waveform being individually compensated and calibrated with respect to an axis with which it is associated. Nine associated matrix multiplying functions which determine the coordinates of a desired slice in its rotated plane are also stored by an external input (by computer or by the clinician operating the system.) Then, in a sequential fashion, digital words for each gradient waveform are read out, multiplied by pairs with the appropriate multiplying function and the three terms are added to form a digital word. These words are converted to an analog value and applied to the respective gradient coils.

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Menlo Park, CA, United States of America

Arthur J Lim