Esaote O-scan eXP, User Manual

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10 / 20 Chapter 5
Computer functions
The processes controlled by the computer are summarized below:
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management of user dialogue (high level commands, image display)
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malfunction control (error messages)
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management of dialogue of all electronic components: each element of
the magnetic unit, thermal control and, if present, magnetic control (low
level commands)
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interception of diagnostics signals notified as error messages to the
user
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acquisition and handling of MR signals to obtain 2D and 3D images for
diagnostic purposes (2DFFT and 3DFFT reconstruction)
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handling of MR images (LUT, zoom, rotations, ROI, distances etc.)
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data base management (patients and images)
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management of communication with workstations, PACS and
DICOM3® printer
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diagnostics programs for service technicians.
The computer controls:
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the gradient amplifier, piloting the waveform, duration and amplitude
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the digital synthesizer, waveform, frequency, phase and amplitude of
the transmission signal on output (also the input of the RF amplifier) and
local oscillator (used by the RF reception system to demodulate the
signals received)
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the RF reception system, controlling fine tuning of the receiving coils
(which depends on the size of the patient's limb) and reception gain.
During acquisition the computer performs a number of pre-processing
functions on incoming data, sending them to the hard disk for temporary
storage. On completion of acquisition, it reconstructs the images (using a
DSP card) and sends them to the disk (for archiving) and to the monitor.
As regards the thermal control, this operates to maintain the magnet
temperature at the set operating value and must remain constantly
active, even when the computer is shut down. It is not controlled by the
computer, but via the temperature sensors located inside the magnet. The
temperature reading is used by the thermal control to change the
temperature of heating elements when necessary. The thermal control
provides the computer with the adjustment values so that it can verify
that the system is operating correctly.