Fluke Biomedical 76-823 - Manual (Page 7)

Operation
Preparing Phantom For Use
2
2-1
Section 2
Operation
2.1 Preparing Phantom For Use
A. Stand the tank upright (with the three inserts inside) on a level surface in a sink or tray. Fill with
water to approximately ¼" from the top. Replace the cover and hand-tighten all the thumbscrews.
Using a funnel through one of the small holes in the cover, add water to fill completely.
B. Screw two thumbscrews into the outer holes on the cover. The small o-rings on these screws need
not be greased.
C. Let the phantom stand overnight to allow dissolved air to dissipate from the water. Add more water
if needed to retain proper level.
D. Fill a syringe with 5 to 10 mCi of the desired isotope (usually technetium). With another syringe,
remove a volume of water from the tank (through the center hole) equal to that of the amount in the
technetium syringe. Now add the technetium through the center hole; and screw in the remaining
thumbscrew. If done carefully, there should be no spillage of radioactive solution. Make sure that all
screws are secure. Mix thoroughly by repeated inversion of the tank. The phantom is now ready for
use. A small air bubble remaining in the tank is of no importance.
2.2 Performance Measurements
The following procedures describe simple techniques for checking the performance of SPECT and PET
systems. You may prefer to alter these procedures for your own purposes.
Place the phantom on the imaging table, its axis perpendicular to the plane of rotation. Carry out the data
acquisition, using the normal number of views and counts per view for a patient study. The results will
thus be equivalent to those obtained in normal patient imaging. The entire phantom is imaged in one
acquisition.
To test maximum system performance, high-resolution data can be obtained at the operator's option by
increasing the number of views and/or counts per view.
As in planar patient imaging, very high-count rates should be avoided because of dead-time losses.
Reconstruction should be performed, using the method typically appropriate for patients. Phantom results,
using several reconstruction and filter parameters, may serve as an aid in determining the method best
used for patients.
A. Resolution - Hot lesions in a Cold Field
Resolution measurements can be made in two ways. Measurements on hot lesions in a cold field
simulate brain and bone scans, for example. Cold lesions in a hot (radioactive) lung and liver scans,
among others.
Procedure
Perform a reconstruction of the Hot Lesion Insert (the acrylic block with the 8 pairs of graded-sized holes).
The largest holes can be seen individually. A blurred image resembling the letter "V" is created by the
holes too small to be distinguished separately. The smallest set of holes seen individually is a measure of
the system's resolution.