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MiniCAT™ User Manual v5.2
© 2014 Xoran Technologies LLC
below.
Maximum Deviation:
The spatial frequency corresponding to the 50% and 10% contrast levels
in the MTF graphs will have the guaranteed lower bounds listed in the table below.
Lower bounds on 50% and 10% contrast cut-off frequencies for MTFs of
different protocols in units of oscillations per centimeter
Protocol
50% Contrast
10% Contrast
Sinus 20s (600), Sinus 40s (600)
3.33
6.00
Sinus 10s (300), Sinus 20s (300)
3.33
6.00
Sinus 10s (150)
3.33
6.00
T Bone 20s (600), T Bone 40s (600)
5.00
10.00
Apparatus
The apparatus for MTF measurement consists of an acrylic cylinder phantom, 10 cm in diameter and
2.5 cm long axially, embedded with a tungsten wire filament. The tungsten wire filament is 50
microns in diameter.
Data Acquisition Methodology
An acquisition and reconstruction of the phantom is made in the desired imaging mode, with the
tungsten filament centered horizontally in the field of view and vertically about the equatorial plane of
the scanner (the plane of rotation of the focal spot). The vertical axis of the phantom should be
aligned as closely as possible with the z-axis of the scanner.
Note that, the vertical axis of the
phantom is NOT the axis parallel to the wire filament. Rather it is the axis around which the
acrylic casing of the wire is circularly symmetric.
The phantom was positioned to maximize the
view of the axial length of the phantom. More viewable slices translate into more data for estimation
and improved MTF estimation accuracy.