Fluke Biomedical 07-645 - Manual (Page 5)

Instructions
Description
1
1-1
Section 1
Instructions
1.1 Description
The Fluoro-Test Tool™ is a fluoroscopic contrast resolution test tool that is based on the work of Wagner,
Barnes and Wu [1]. The test tool consists of two 6" x 6", 6.1 mm (¼") thick aluminum plates with each
plate containing an array of 1.1 cm targets of varying contrast. Also included in the Fluoro-Test kit are
three 6" x 6", 1 mm thick copper sheets. The test tool is designed to be used with the copper attenuator
sheets positioned close to the source (i.e., at table top) and the aluminum test plate located close to the
image intensifier input as illustrated in Figure 1-1. With 2 mm of copper attenuator in the beam and a
fluoroscopic x-ray tube potential of 80 kVp, the contrast of the targets in Plates A and B are given in
Figure 1-2A and 1-2B, respectively. Each plate has three rows of three targets with a moderately large
(≅3%) contrast increment between adjacent targets in the same row. The outer two rows have increasing
target contrast increments while the middle row is offset and has decreasing increments. At 80 kVp with 2
mm of Cu attenuator the targets range in contrast from ≅1% to ≅9% in Plate A (integer phantom) and from
≅0.5% to ≅8.5% in Plate B (half-integer phantom).
1.2 Instructions for Use
1. For conventional geometry fluoroscopic units (under-table x-ray tube/over-table imaging chain)
place two copper sheets (i.e., a total copper thickness of 2.0 mm) on the tabletop and aluminum
Test Plate A directly beneath the image intensifier input phosphor or spot film device cover as
shown in Figure 1-1. The spot film device/imaging chain should be positioned 12" to 16" above the
tabletop. If the fluoroscopic unit has an over table x-ray tube/under table imaging chain, place the
copper sheets directly beneath the collimator and Test Plate A on the table top or on the image
intensifier. In either geometry the copper sheets and Test Plate should be centered in the
fluoroscopic field-of-view (FOV).
2. If the image intensifier has different FOVs, select the 22 cm (9") FOV or the FOV that is closest to
22 cm.
3. Note the fluoroscopic kVp. Scan the image and note the number of targets that can be seen in each
row.
4. Replace Test Plate A with Test Plate B and repeat step 3. In general the fluoroscopic kVp will
remain the same.
5. The target contrast visibility threshold or low contrast resolution can be ascertained by determining
the lowest contrast target that is seen in the two plates. The contrast of targets on Plate B are
slightly less (≅0.5%) than the targets in Plate A and, if the same number of targets are seen on
each plate, the contrast resolution is the lowest contrast target seen in the image of Plate B. If more
targets are seen in the image of Plate A, the contrast resolution is the lowest contrast target seen in
Plate A. The contrast of the targets for a beam hardened by 2.0 mm of copper are given in Table 1
as a function of fluoroscopic x-ray tube potential.