Equipment Testing

The TO is composed of a series of:

0.75 mm diameter stainless steel rods arranges in a pattern between 2 transparent plastic sides

What can be calculated if you know the above:

1. Frequency 2. PRF 3. Duty factor

A good equipment QA program must include 3 componenets

1. Making regular measurements of parameters (sensitivity, range accuracy, dead zone, det res) 2. Record keeping 3. Scheduling of service calls

From a hydrophone what things can be determined:

1. Period 2. PRP 3. Pulse Duration

Devices used for measuring equipment performances can be divided into 2 classes:

1. Test object 2. Tissue equivalent phantom (TEP)

If Prop Speed is known, what can be calculated:

1. Wavelength 2. SPL

The following parameters can be tested using TO:

1. relative system sensitivity 2. axial resolution 3. lateral resolution 4. dead zone 5. range accuracy 6. TGC operation 7. dynamic range

TEPs must have a prop speed of, and an attenuation of:

1540 m/s 1/2 dB/cm/MHz

What % error in measurement in acceptable:

2%

Rods are positioned

2, 4, 6, 8, 10 mm at the TOP surface

Along one side of the TO is a vertical group of rods spaced:

25, 20, 15, 10, 5, 3 mm apart

The rods in the TO are arranged into :

5 groups- each testing a different parameter

Relative system sensitivity:

A measure of how weak a reflection an instrument can display with thte power and overall gain set to the lowest setting w/o using TGC

Range accuracy:

A measure of the machines time base and how linear this time base remains over the whole image

What does a hydrophone measure:

Acoustic pressures which are then used to calculate relative intensities

AIUM:

American Institute of US Medicine

Lateral resolution is dependent upon:

Beam width

TO decreases in what temp:

COLD

Axial resolution is used to check for:

Consistency rather than accuracy

Lateral resolution varies with:

DEPTH

Metal pins or nylon threads are positioned to test:

Detail resolution and range accuracy

Pulse length is related to:

Frequency and Bandwidth

TEP's are made of:

Graphite filled aqueous gel or urethane rubber materials - graphite is used to produce scattering which stimulates soft tissue

TEP:

Has the same measurement elements of a test object but the elements are set inside a material that provides attenuation and scattering as in soft tissue

Acceptance Testing:

INITIAL testing of equipment prior to acceptance of the manufacturer

If impedance is known, what can be calculated:

Intensity

Since the power and overall gain setting is at the lowest, reverberation should be at its:

Minimum - leaving pulse length as the determining factor

A hydrophone is displayed on an:

Oscilloscope

Axial resolution depends upon:

Pulse Length

The dead zone is determined by the:

Pulse length and reverberation artifact

Quality Assurance Testing:

ROUTINE testing of equipment to ensure proper functioning - monitors performance with the use of TO and TEP

What may have an affect on the velocity of sound:

TEMPERATURE

What rods are used for axial resolution and how are they space apart:

The 6 middle rods 5, 4, 3, 2, 1, mm apart

Hydrophone is used to measure:

The acoustic output power of US instruments

Minimum sensitivity:

The amount of overall gain necessary to BARELY see one rod

Normal sensitivity:

The amount of overall gain necessary to CLEARLY see all pins in the TO

Dynamic Range:

The difference btwn gain settings that produce barely seen and max. brightness displays for the same reflection

Dead Zone:

The distance closest to the XDCR in which imaging cannot be performed - NO INFO AREA

Lateral Resolution:

The minimum reflector separation perpendicular to the sound path required for separate reflections to be produced

Axial Resolution defined:

The smallest distance between any two rods in the group that can be seen separately

TO is filled with a mixture of:

Water, alcohol, and algae inhibitor that has a prop seep of 1.54 mm/us at ROOM TEMP

Test object:

composed of material in which the veolicty of the US is the same as tissue (1.54 mm/us) but uses no materials that attempt to imitate tissue characteristics

A wide BW is used to produce a:

short pulse

A hydrophone consists of:

small XDCR elements mounted on the end of a narrow tube or hollow needle

Axial Resolution:

the minimum reflector separation along the sound path required for separate reflections to be produced

Lateral resolution defined:

the spacing of the two closest rods in the group that are seen separately on the display