Fluke 84-350 User Manual

Nuclear Associates 84-350

Near Field Ultrasound Phantom

February 2005
Manual No. 84-350-1 Rev. 2
©2004, 2005 Fluke Corporation, All rights reserved. Printed in U.S.A.
All product names are trademarks of their respective companies

Users Manual

Fluke Biomedical

Radiation Management Services

6045 Cochran Road
Cleveland, Ohio 44139

440.498.2564

www.flukebiomedical.com/rms

Table of Contents

Section 1: Introduction................................................................................................ 1-1

1.1 Introduction .................................................................................................. 1-1

1.2 Description................................................................................................... 1-1

1.3 Testing Procedures...................................................................................... 1-3

Section 2: Handling Instructions ................................................................................ 2-1

2.1 Handling Instructions ................................................................................... 2-1

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Introduction

Introduction

1

Section 1

Introduction

1.1 Introduction

This phantom is constructed from a patented solid elastic material called Zerdine™. Zerdine, unlike other
phantom materials on the market, is not affected by changes in temperature. It can be subjected to boiling
or freezing conditions without sustaining significant damage. Zerdine is also more elastic than other
materials and allows more pressure to be applied to the scanning surface without subsequent damage to
the material. At normal or room temperatures, the Zerdine material found in the Near Field Phantom will
accurately simulate the ultrasound characteristics found in human breast tissue. The 84-350 contains low
scatter masses in a range of sizes and depths, a calibrated volumetric test object and an assortment of
nylon monofilament target groups. The phantom is protected by an acrylic case and plastic membrane to
facilitate scanning and minimize desiccation. The 84-350 was designed to allow for assessment of
linearity, axial and lateral resolution, depth calibration, dead-zone measurement, volumetric calibration
and registration.

The Nuclear Associates series of ultrasound phantoms, unlike human subjects or random scannable
materials, offers a reliable medium that contains specific, known test objects for repeatable qualitative
assessment of ultrasound scanners over time.

1.2 Description

Background Material

The manufacturer maintains specific proprietary fabrication procedures that enable close control over the
homogeneity of Zerdine and the reliability of its acoustic characteristics from batch to batch. The speed of
sound in Zerdine can be adjusted between 1430 and 1650 meters per second. The acoustic attenuation
can be adjusted between .05dB/cm/MHz and 1.50 dB/cm/MHz. The relation between the acoustic
attenuation A and the acoustic frequency F is of the form A = A°F
in the range of .8 to 1.10, indicating the proportional increase of the acoustic attenuation with frequency.
Backscatter characteristics can be adjusted through the addition of predetermined amounts of calibrated
scatter material. Zerdine can be molded into very intricate shapes and the material can be cured in layers,
allowing the production of "multi-tissue" phantoms. Zerdine, like most other phantom materials will
desiccate if unprotected, but Zerdine has a sponge-like property. Any moisture lost to evaporation will be
reabsorbed when the material is immersed in water. Barring any damage to the case or scanning
membrane, the phantom should lose only minimal amounts of moisture over time.

Near Field Resolution Target

The target consists of parallel 0.1 mm nylon wires horizontally spaced 6 mm apart from center to center.
Vertical distance from the center of each wire to the top edge of the scanning surface ranges from 9 mm
down to 1 mm in 1 mm increments (see Figures 1-1 and 1-5). This target is designed to measure a
transducer's dead zone, otherwise referred to as the "ring-down distance.”

n

with values of the power coefficient n

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Operators Manual

Figure 1-1.

Lateral Resolution Target

The target is positioned 1.5 cm deep to allow testing of short distance transducers. Extremely fine
monofilament wires with a diameter of. 1 mm are used to avoid any possibility of one wire acoustically
shadowing another. Five parallel wires are horizontally spaced precisely 5, 4, 3, 2 and 1 mm distances
apart from center to center (see Figures 1-2 and 1-5).

Figure 1-2.

Vertical Resolution Target

The target consists of six pairs of parallel .1 mm wires, horizontally spaced 6 mm apart from center to
center. The lower wire in each pair is horizontally offset from the upper wire by 1 mm to further reduce
any acoustic shadowing effects. The vertical distance between each pair of wires is 5, 4, 3, 2, 1 and .5
mm from center to center (see Figures 1-3 and 1-5). This garget is designed to accurately assess vertical
resolution capabilities at a depth of 2 cm.

Figure 1-3.

1-2

Introduction

Description

1

Vertical Plane Target

A group of 0.1 mm parallel wires are positioned 1 cm apart down the center of the phantom in a vertical
plane (Figure 1-5). When scanned from the top, this target enables measurement of vertical linearity,
depth calibration and gain as a function of depth.

Scatter Targets

Three groups of cylinders with diameters of 1.6, 2.0 and 2.4 mm are arranged in a specified pattern at a
designated position in the phantom. The cylinders have a backscatter that is approximately 15 dB lower
than the background, and enable the identification of a system's anechoic mass detectability threshold.

Figure 1-4.

Calibrated Volumetric Test Object

One mass with a specific calibrated volume is embedded at one end of the phantom approximately 3 cm
deep. The backscatter within the test subject is approximately 9dB lower than the background. This target
is designed for evaluation of spatial measurements and volumetric calculations.

1.3 Testing Procedures

Dead-Zone Identification

The transducer should be placed firmly above the near field resolution target and perpendicular to the
wires. Dead zone or the ring down distance can be defined as that distance between the transducer's
face and the closest wire target to be resolved from the reverberation. If the first target to be resolved is at
4 mm, then the dead zone distance is "something less than 4 mm."

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Operators Manual

Figure 1- 5.

Assessment of Resolution

These measurements should be done at several sensitivities and depth levels to facilitate a thorough
evaluation. As defined by the AIUM standards committee, lateral resolution "at specified control settings
and range is the minimum lateral distance between two identical reflectors or scattering volumes at which
separate registrations can be clearly distinguished on the display." A simple measurement can be taken
at a depth of 1.5 cm using the lateral resolution target. A more thorough evaluation can be done using the
vertical plane target (refer to section on beam width measurement). Closer positioning of the transducer's
focal point to each target group should result in better resolution. Assessment of vertical resolution should
be done in the same manner as assessment of lateral resolution using the vertical resolution target that is
located approximately 30 mm from the scanning surface.

Depth Calibration

This measurement should be performed using the vertical plane targets. This group of wires should be
scanned linearly and to the target plane. All wires should be displayed simultaneously. Measure the
distance between two targets using the display markers and plot the values as a function of true distance
that is known to be 20 mm. Or, more simply, align the echoes to the display markers for comparison.

Beam Width Measurement

A linear scan should be performed perpendicular to the vertical plane target. Some of the monofilament
wires are displayed as lines rather than points. The determined length of these displayed lines
demonstrates beam width as a function of depth in 1 cm increments.

Anechoic Mass Detectability

1-4

Introduction

Testing Procedures

Optimize imaging conditions for anechoic masses through adjustment of TGC, gain, output, focal depth,
etc., and record settings. Image each set of targets and determine the diameter and/or depth at which the
masses can no longer be faithfully resolved.

1

Volumetric Measurements

Each phantom will identify the specific size dimensions and volume of the embedded test object. Use
standard measurement procedures and compare results with known values.

NOTE

Time-gain properties and sector scanner errors can
be evaluated using the vertical plane target in
accordance with suggested AIUM techniques. For
targets with minimum scattering, lower gain levels
can be used, however, higher gain settings enable
evaluation at more clinical-type settings. When
evaluating any machine, settings should be
recorded and remain consistent over time. For
further instruction on measuring performance, refer
to Standard Methods for Measuring Performance of
Pulse-Echo Ultrasound Imaging Equipment AIUM
Standards Committee, July, 1990.

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Handling Instructions

Handling Instructions

Section 2

Handling Instructions

2.1 Handling Instructions

1. Remove acrylic cover which protects the scanning membrane.

2. Fill the scanning cavity with water or suitable coupling material.

3. Apply the appropriate transducer to the membrane using normal pressure. The phantom material

and membrane are semi-elastic but can be damaged if excessive pressure is used.

4. Test ultrasound equipment in accordance with procedures suggested above or AIUM

recommendations.

5. When all testing is complete, remove excess coupling material and replace the protective acrylic

cover.

6. It is suggested that the phantom be stored at room temperature, avoid extreme temperatures.

7. Zerdine will desiccate over time if the watertight envelope is compromised. If there is a noticeable

change in the phantom or the case and/or membrane are damaged, the phantom should be
returned immediately for repair or replacement

2

2-1

Fluke Biomedical

Radiation Management Services

6045 Cochran Road
Cleveland, Ohio 44139

440.498.2564

www.flukebiomedical.com/rms