ULTRASOUND

Question 1

consists of many components, each of which has a separate operation to perform. This starts with transmitting and receiving ultrasound signals which are then processed to form the images that we see on screen.

Answer 1

diagnostic ultrasound machine

Question 2

The internal components that make up a typical ultrasound machine are the following:

Answer 2

• Transducer
• Pulser
• Beam former
• Receiver
• Processor
• Display
• Digital storage
• Hard copy printer devices

Question 3

Diagnostic transducers are made from __

Answer 3

piezoelectric materials

Question 4

As a consequence of this they can act as a transmitter and receiver of ultrasound. They are able to produce beams which can be directed in various ways which are controlled by the ultrasound machine to improve image quality.

Answer 4

Transducer

Question 5

materials and are able to convert electrical energy into ultrasound energy and vice versa.

Answer 5

Transducer

Question 6

Changes in the applied __ to the transducer changes the strength and intensity of the ultrasound beam, and affects the overall brightness of the B-mode image.

Answer 6

voltage

Question 7

The ___ produces the electric voltage that drives the transducer. This driving voltage governs the output power of the ultrasound machine and can be adjusted by the operator through the power or output control

Answer 7

pulser

Question 8

Increasing the applied voltage to the transducer increases the ultrasound pulse intensity, resulting in an increase in the overall ___ of the image.

Answer 8

brightness

Question 9

The greater the applied voltage, the stronger the ultrasound pulse and the higher the __

Answer 9

pulse intensity

Question 10

The ___ controls the shape and direction of the ultrasound beam and the scanning patterns used to form the images that we see.

Answer 10

beam former

Question 11

As a consequence of attenuation the returning echo amplitudes and intensities are___

Answer 11

decreased

Question 12

beam former: this enables the operator to have indirect control of:

Answer 12

• depth
• focus
• sector width
• zoom

Question 13

job is to to combat attenuation, i.e. the energy lost from the beam a sit propagates through soft tissue.

Answer 13

Receiver

Question 14

energy is lost from the beam through absorption which is mainly converted into __

Answer 14

heat.

Question 15

The ultrasound machine can compensate for the effects of attenuation by amplifying the received signals in two ways, using the ___ and __

Answer 15

overall gain and the time-gain compensation (TGC) controls.

Question 16

The processor can be divided into two individual parts, each having very different tasks to fulfil, and consists of:

Answer 16

signal processor and image processor

Question 17

converts echo voltages to video signals

Answer 17

signal processor

Question 18

formats the many scan line data into image form.

Answer 18

image processor

Question 19

cleans up the signal, removing unwanted noise, and also controls the signal bandwidth

Answer 19

Filtering in Processor

Question 20

performs a process of demodulation which means it converts the received signal voltages into video form, retaining the amplitude information required for B-mode imaging

Answer 20

Amplitude detection in Processor

Question 21

controls the dynamic range of the B-mode image (the number of shades of gray displayed in the image)

Answer 21

Compression in Processor

Question 22

Once the signals have passed through the signal processor they are fed into the ___

Answer 22

image processor

Question 23

The ___ performs operations such as scan conversion which reformats the scan line data into two-dimensional images, i.e. either___

Answer 23

image processor; linear or sector form.

Question 24

There is a range of processing performed on the image data prior to and following storage into memory before they are finally sent to the display. Functions such as edge enhancement are known as ___ because they are performed before being stored.

Answer 24

pre-processing functions

Question 25

stores a number of sequentially acquired and processed static image frames every second which are rapidly sent to the display to provide dynamic real-time ultrasound.

Answer 25

Image memory

Question 26

This process can be interrupted by activating the___ which stops any further acquisition and processing of data from the transducer.

Answer 26

freeze control

Question 27

In freeze mode only ___ in the memory is displayed. The numerous frames of image data held and stored can be reviewed in turn using the machine’s __ function.

Answer 27

one static image; cine loop control

Question 28

There are only two controls that can be adjusted on most displays, which are ___

Answer 28

brightness and contrast

Question 29

The images displayed on screen can be sent out to an external hard copy device such as ___ and __

Answer 29

radiographic film or thermal paper printers.

Question 30

The images displayed on screen can be sent out to an external hard copy device such as radiographic film or thermal paper printers. Alternatively, the images, which can also consist of short cine loop review video clips, can be digitally stored on the machine’s hard disc or alternatively burnt to CD or DVD.

Answer 30

Hard Copy and Soft Copy Storage

Question 31

Many ultrasound departments are linked into a __ This enables images such as X-rays and ultrasound scans to be stored electronically and viewed on any __display monitor around the hospital at the touch of a button.

Answer 31

picture archiving and communications system, more commonly known as PACS.

Question 32

Different types of ultrasound transducers:

Answer 32

Linear array, Curvilinear array, Phased array

Question 33

type of transducer: Produces a rectangular field of view

Answer 33

Linear array

Question 34

type of transducer: Produces a wide "sector" field of view

Answer 34

Curvilinear array

Question 35

type of transducer: small footprint Produces a "sector" field of view

Answer 35

Phased array

Question 36

Ultrasound transducers are described by their type and operating frequency which can range from __ and are selected based on their ‘fitness for purpose’.

Answer 36

2MHz up to 20 MHz

Question 38

We need to be aware that there is a trade-off between image resolution and the penetrating depth of ultrasound which is governed by its __

Answer 38

frequency.

Question 39

In general use, the ___ which will reach the required depth should always be employed.

Answer 39

highest frequency transducer

Question 40

An ultrasound transducer converts __ and ___ and back again, based on the piezoelectric effect.

Answer 40

electrical energy into mechanical (sound) energy

Question 41

It is the hand-held part of the ultrasound machine that is responsible for the production and detection of ultrasound waves.

Answer 41

ultrasound transducer

Question 42

The main components of a typical ultrasound transducer consist of:

Answer 42

* physical housing assembly * electrical connections * piezoelectric element * backing material * acoustic lens * impedance matching layer.

Question 43

This contains all the individual components including the crystal, electrodes, matching layer, and backing material. This housing provides the necessary structural support and acts as an electrical and acoustic insulator.

Answer 43

Physical housing

Question 44

Two electrical connections are formed on the front and back face of the crystal by plating a thin film of gold or silver on these surfaces. These electrodes are connected to the ultrasound machine which generates the short burst of electrical pulses to excite the crystal and through the piezoelectric effect generates a pulse of ultrasound energy.

Answer 44

Electrical connections

Question 45

They also discovered that the converse was true, i.e. if a short electrical burst was applied to these crystals it would cause them to__. The term ‘piezoelectric’ was derived from the Greek word__, meaning to press or squeeze.

Answer 45

vibrate; ‘piezein’

Question 46

Piezoelectric element is made of ___

Answer 46

Quartz

Question 47

__ is a naturally occurring material with piezoelectric properties and was extensively used in the development of early machines. This has now been superseded by man-made ceramics such as __ which are more efficient, have better sensitivity, and can easily be shaped.

Answer 47

Quartz; lead-zirconate-titanate (PZT)

Question 48

The operating frequency of a transducer is critically governed by the __. For maximum efficiency the crystal should be operating at its___ frequency. This occurs when the thickness of the crystal corresponds to half a wavelength (λ/2).

Answer 48

thickness of the piezoelectric crystal; ‘natural’ or ‘resonant’

Question 49

Typical diagnostic ultrasound elements are between ___

Answer 49

0.2 mm and 1 mm thick

Question 50

To try and eliminate the vibrations from the back face, and to control the length of vibrations from the front face a ___ is used.

Answer 50

backing or damping material

Question 51

This damping material, which typically consists of __ and __ , is attached to the back face of the piezoelectric crystal.

Answer 51

tungsten powder; plastic or epoxy resin

Question 52

A refractive element such as plastic or rubber lens placed in front of a flat crystal to focus the ultrasound beam.

Answer 52

Acoustic Lens

Question 53

Sandwiched between the PZT crystals and the patient’s skin is a __ and __

Answer 53

matching layer and acoustic coupling.

Question 54

is fashioned to be one-quarter wavelength and of intermediate acoustic impedance between that of the piezoelectric crystals and soft tissue.

Answer 54

matching layer

Question 55

Acoustic coupling between the transducer and the patient’s skin consists of copious amounts of___

Answer 55

gel or mineral oil.