Fluke Biomedical 76-903 - Manual (Page 14)

Nuclear Associates 76-903
Operators Manual
3-6
Figure 3-9. 0.5 mm x 0.5 mm 2 , 0.75 mm x 0.75 mm 2 , 1.0 mm x 1.0mm 2 , and 2.0 mm x 2.0mm 2
square holed.
Five of each dimension. Hole depth, 0.5”.
T
1
and T
2
Solution Insert
This insert (Figure 3-10) holds six (6) 5 cc glass vials (15 mm diameter x 47 mm high) that can hold
solutions of varying T
1
and T
2
values. One should note that measured T
1
and T
2
values depend on many
parameters including field strength and imaging sequence used.
Figure 3-10. T
1
, T
2
Solution Insert. Six 5 cc refillable glass vials with caps. (15 mm diameter x 47 mm
height.)
3.4.6 Star Pattern
Modulation Transfer Function (MTF)
Modulation transfer function (MTF) is a mathematical concept that provides an objective measurement of
the combined effect of image sharpness and resolution. Direct measurement of MTF is often very difficult
and calculation of MTF based on measurable parameters such as point-spread function (PSF) or line
spread function (LSF) are clearly outside the scope of this manual. Difficult as it may be to have precise
mathematical definition, it is however relatively easy to present MTF in a qualitative manner. Similar
techniques are used to evaluate x-ray focal spot sizes using a star pattern.
The star pattern developed for this purpose is particularly useful in MR imaging where resolution in
vertical and horizontal axes can be different and certain image artifacts that are peculiar to Fourier
imaging may not be visible under any other test.
• MTF Evaluation
• Horizontal & Vertical Spatial Resolution
• Quadrature Setting
• Baseline Correction
Figure 3-11. Wedge angle, 3°. Number of wedges, 9. Fan angle, 60°. Wedge length, 3". Width, 2".