title: Software and hardware integration of a microprogrammable state machine for NMR imaging.
abstract: We have integrated a commercially available microprogrammable state machine (Tecmag PULSkit) for use as a magnetic resonance pulse programmer. Providing the capability for active research environment imaging protocols, it features timing resolution of 100 nsec, ten 16-bit loop counters, and individually addressable look-up tables. This integration involved hardware and software integration with a VAX 11/750 at several levels. Hardware: Each of the three gradient channels employs three digital-to-analog converters (DACs). An 8-bit, 4-quadrant, multiplying DAC generates the gradient waveform shape. A 12-bit DAC generates the multiplying DAC scaling voltage, controlling gradient amplitude and sign. A third 12-bit DAC produces a gradient offset (shim) voltage. An eddy current compensation network is present for each gradient channel. Software: The software design philosophy was to create a flexible interface (interactive window environment), while not constraining complex manipulation of the hardware (direct use of the pulse-sequence compiler primitives and microprogramming). The software levels include (a) pulse-sequence microprogramming, (b) pulse-sequence compiler, (c) interactive parameter specification, and (d) canned pulse-sequence microcode library.
authors.affiliation: Department of Radiology, University of Cincinnati, Ohio 45267-0579.
authors.forename: B K
authors.initials: BK
authors.lastname: Stewart
authors.forename: R G
authors.initials: RG
authors.lastname: Pratt
authors.forename: S R
authors.initials: SR
authors.lastname: Thomas
authors.forename: S L
authors.initials: SL
authors.lastname: Dieckman
authors.forename: T H
authors.initials: TH
authors.lastname: Ridgway
mesh_terms: D003199:Computer Systems; D003201:Computers; D004867:Equipment Design; D007091:Image Processing, Computer-Assisted; D016247:Information Storage and Retrieval; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008838:Microcomputers; D012984:Software