Fluke Biomedical 76-903 - Manual (Page 6)

Nuclear Associates 76-903
Operators Manual
1-2
1.4 NMR Solution
Any NMR signal-producing solution can be used to fill the phantom. It is desirable to use solutions with T
1
and T
2
values around 500 - 1000 sec, because it can better simulate the clinical imaging conditions. One
should note that
T
1
and T
2
values depend on the magnetic field strength.
Filling the phantom requires special care to avoid any trapped air bubbles. Water can be degassed by first
boiling and cooling prior to filling. Use of a wetting agent and algicide can also prolong the useful life of
the solution. A fairly full phantom can be placed in a vacuum chamber to eliminate the bubbles. One way
to avoid the trapped bubbles, especially in small holes, is to fill the holes with solution using a small
syringe needle. This may require disassembling the phantom.
Any solution can be used; however, for higher field systems, solutions with chemical shift should be
avoided. Copper sulfite or manganese chloride were found to be useful.
A water solution of 0.1 millimolar manganese chloride can be used to fill the phantom. The T
1
value of this
solution is approximately 500 msec. A shorter relaxation time is not suggested, as it may not correctly
represent the system performance in a realistic clinical environment.
Table 1-1. Summary of Imaging Parameters
Orientation:
Imaging Technique:
TE= Shortest possible
TR=
Number of Slices =
Slice Thickness =
Slice Sequence = Interleaved or others
Slice to Slice Gap =
Number of Encoding = 256, 128 or 64
Signal Averaging = No averaging, single
RF Tuning Parameters (i.e. attenuation settings):
For daily QA, exactly same parameters using same
pulse sequence should be used.
NOTE