Esaote O-scan eXP, Руководство пользователя

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350004900 Rev. 07 3 / 8
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Manual Requirement
s
EER - Acronym for Early Enhancement Rate indicating the capture speed
of the contrast bolus.
EFFECTIVENESS - Accuracy and completeness with which the operator
reaches set objectives.
EFFICIENCY - Resources used in relation to the accuracy and
completeness with which the operator reaches set objectives.
FERROMAGNETIC - A large positive magnetic susceptibility in a substance,
such as iron.
FIELD GRADIENT - A magnetic field which changes in strength in a given
direction. These fields are used in MR to select, together with the selective
excitation, the imaging region. Also used to encode the MR signal received
from the region examined with spatial information. Measured in T/m.
FIELD OF VIEW - The area of the slice from which the system acquires
information.
FREQUENCY - The number of repetitions of a periodic process per unit of
time. For electromagnetic radiation is measured in Hz.
GAUSS - The old unit of measure of the magnetic field.
GEOMETRIC DISTORTION - Deviation from the spatial position of the
structure displayed with respect to the expected real position of the
object.
GRADIENT - The amount and direction of the rate of change in space of
some quantity, such as magnetic field strength.
GRADIENT COIL - Current-carrying coils designed to produce a desired
magnetic field (so that the magnetic field will be stronger in some
locations than in others). Correct design of the size and configuration of
the coils is necessary to produce a controlled and uniform gradient.
GRADIENT OUTPUT - Parameter regarding gradient performance, as a
percentage of the variation in magnetic field intensity, or the electric field
induced by one or more gradients in a certain position and in specific
conditions.
GRADIENT SYSTEM FOR SPECIAL PURPOSES - Gradient system designed
for use in special purpose MR systems.
An example of a special purpose gradient system is one that can be
incorporated in an MR system to enable special examinations of the head.
G
X
, G
Y
, G
Z
- Conventional symbols for gradient magnetic fields. x, y, and z
denote the spatial direction of the gradient component, i.e., direction
along which the field changes.
HOMOGENEITY - Uniformity. In MR, the homogeneity of the static
magnetic field is an important criterion of the quality of the magnet.
HOMOGENEITY REGION (OF THE MAGNET) - 140 mm diameter sphere,
centered in the isocentre of the magnet, in which the magnetic field is
homogeneous.