Ultrasound physics- Chapter 11

With A-mode, what is displayed on the y-axis?

Amplitude of the reflected signal

The mode that produces lines related to the changing position of reflectors in the body with respect to time is called _______. A. A-mode B. M-mode C. B-mode D. a la mode

B. The imaging mode that displays he position of reflectors throughout time is M-mode, or motion mode. M-mode is the only display that provides reflector position throughout time.

Which of the following forms of focusing is different from the others? A. lens B. mirror C. phased D. dynamic receive

D. Dynamic receive focusing is accomplished during reception of reflected sound . The other three techniques are forms of focusing during transmission.

True or False? The "curved pattern" of delays in the electrical spikes used in a linear phased array transducer focuses the beam during transmission.

True. Focusing using time delays of the electrical spikes is a form of transmit focusing.

There is communication between the pulser of the ultrasound system and the piezoelectric crystal of the transducer.

True. The transducer's PZT must be a directly connected to the pulser electronics of the ultrasound system. A wire provides a route for the electrical signal to travel from the pulser to the PZT. In addition, the catalo sends data back to the system regarding the reception of reflect echoes. this data goes tot the receiver ad creates an image.

True or False? All phased array transducer systems direct ultrasound pulses in any directions to create a two-dimensional image.

True. To create a two-dimensional image the sound beams of annular, linear and curvilinear phased array transducers must be steered through a path. The linear and curvilinear phased array systems steer the beam electronically, whereas the annular phased array steers the beam mechanically.

The ultrasound beam is directed in many different directions to create an imaging plane.

True. With a mechanical transducer, the active elements is aimed in several directions so that the pulses cease a two-dimensional picture. Without this beam steering the pulses would travel in the same direction and display only a single B-mode line.

True or False? Annular phased array transducer focus sound beams in all planes and at all depths.

True. With annular arrays, the sound beam has the appearance of a straw. It is focused in all planes and at all depths.

The ultrasound beam is not focused electronically.

True. With mechanical transducers, focusing is not achieved electronically. The beam is focused with acoustic (lens external) or by a curved PZT crystal (internal).

True or False? Both linear and phased array technologies have the ability to variable focus an ultrasound beam to different depths.

True. With the phased delivery of electrical pulses to the crystals, the ultrasound beam may be focused at a variety of different depths.

In M-mode, what is displayed on the x-axis?

time

With these transducers, the ultrasound beam is focused with an acoustic lens, a mirror, or by milling the piezoelectric crystal in a curved shape. A. linear switched array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer

A, C, and E Acoustic beams can be found with techniques similar to those that focus light waves, including using an acoustic lens, a focusing mirror, or a curved piezoelectric crystal. Mechanical transducers and some linear and curvilinear array transducers use these techniques to focus acoustic beams.

These transducers focus the ultrasound beam electronically. A. linear switched array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer

A,B,D, and E. Electronic focusing techniques are used in linear phased array and annular phased array transducers. A focused acoustic beam produces images with greater detail. Some linear and convex array transducers focus the beam electronically, whereas other do not.

Which imaging technique usually displays a single jagged line of varyhing heights? A. A-mode B. B-mode C. C-mode D- I-mode

A. A-mode displays reflected echoes as spikes of varying height. Echo amplitude appears on the y-axis, and reflector depth on the x-axis. the spike's location on the x-axis is based on the pulse's time of flight. The height of the is determined by the reflection's strength. Stronger reflections create higher spikes.

The patterns of electrical signals exciting the piezoelectric crystals of oinerar phased array transducer. A. typically changes from one acoustic pulse to the next B. changes every fourth or fifth acoustic pulse C. changes only when the maximum imaging depth changes D. none of the above

A. The pattern of the electrical signals that excite the PZT crystals of a linear phased array transducer changes from one pulse to the next. The electrical patterns determine the direction and focusing of each acoustic pulse. Each sound wave is directed in a slightly different direction to crate a two-dimensional imaging plane. Thus, the electrical signals vary for each acoustic pulse. The electronics that creates the varying patterns is called the beam former.

Which two of the following terms are associated with phased array transducers? A. lens B. multi-focus C. mirror D. adjustable E. external

B and D. Phased array is always associated with adjustable or multi-focusing.

Which mode provides the foundation for real-time, gray scale anatomic imaging?

B-mode, or brightness mode

The minimum number of active elements in a mechanical transducers is: A. 0 B. 1 C. 2 D. none of the above

B. A mechanical transducer may be constructed with minimum of a singe piezoelectric crystal. An imaging plane is crated by mechanically steering the single crystal with a motor.

All of the following describe dynamic receive focusing except: A. delay pattern changes continuously throughout reception B may be used by singe crystal transducers C. focusing occurs at many depths D. automatically performed by system

B. Dynamic receive focusing is used only with systems using array transducers. Focusing is accomplished automatically during reception and is outside the control of the Sonographer.

Which best describes the elements in a linear phased array transducer? A rectangular, 1/4 wavelength thick B rectangular, 1/2 to 1/4 wavelength wide C. circular D. squares, 1/2 wavelength thick

B. Each element of a linear phased array is rectangular. there are approximately 100 to 200 elements, each having a width of 1/4 to 1/2 wavelength.

With the transducers, the ultrasound beam is steered by a motor, a rotating reflecting mirror, or a similar device. A. linear switched array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer

C and D. In mechanical and annular phased array transducers, an ultrasound beam is steered using mechanical devices such as motors or mirrors.

What image is created with a two-dimensional array transducer? A. two-dimensional static image B. two-dimensional real-time image C. three-dimensional real-time image D. B-mode

C. A two-dimensional array transducer creates a three-dimensional image.

Which imaging modality places dots of dissimilar gray scale on the display? A. A-mode B. I-mode C. B-mode D. M-mode

C. Brightness mode, or B-mode, displays reflected echoes as spots of varying brightness. The depth of the dot is based on the time of flight. Stronger reflections create brighter dots. Weaker reflections create darker dots.

Which best describes the elements in a linear sequential array transducer? A. rectangular, 1/4 wavelength thick B. rectangular, 1/4 to 1/2 wavelength wide C. rectangular, 1 wavelength wide D. squares, 1 wavelength thick

C. Each element of a linear sequential array is rectangular. There are many elements, each with a width of one wavelength.

How are the piezoelectric crystals excited when using an ultrasound system with a sequential linear array transducer? A. singly and in order: the first crystal, the second crystal, etc B. in pairs: the first 2 crystals, the 3rd and 4th, etc C. in a specific order D. in a random sequence

C. Sequential linear array transducers fire small groups of piezoelectric crystals in a specific succession or progression. The order of firing is determined by the manufacturer, and is closed to produce the highest quality image. There is, however, no specific order that all linear arrays use. The firing pattern is best described as "in a specific order."

With B-mode, on which axis is the strength of the reflection input? A. x-axis B. y-axis C. z-axis

C. With B-mode, reflection strength is input into the z-axis.

Which imaging modality places time-of-flight information on the x-axis and echo amplitude on the y-axis? A. M-mode B. L-mode C. J-mode D. A-mode

D. A-mode, or amplitude mode, displays reflector depth on the x-axis. Reflector depth is determined by a pulse's time of flight. The strength of the reflection is displayed on the y-axis.

Which imaging mode accurately displays reflector depth? A. I-mode B. L-mode C. C-mode D. A-mode

D. A-mode, or amplitude mode, displays the reflector depth accurately. A-mode is used in ophthalmology, which requires praise measure of depth or thickness.

To which of the following do the x-axis of a B-mode, the y-axis of an M-mode and the x-axis of an A-mode all related? A. depth of view B. go time C. echo amplitude D. time of flight

D. All the three of these measurements report the reflector depth. Reflector depth is determined by a pulse's time of flight.

What is true of the electrical pulses that excite the active elements of an annular phased array transducer? A. they arrive at each piezoelectric crystal at exactly the same time. B. they vary in amplitude based on the direction of the steering and focusing C. they excite the crystals at different times, nanoseconds apart. D. they arrive at each PZT crystal at different times, microseconds apart.

D. Annular array technology fire the piezoelectric crystals in a particular sequence to produce a focused ultrasound beam. The electrical pulses that excite the ringed elements of the array arrive at slightly different times, separated by only very small fractions of a second.

What is the shape of the elements in an annular phased array transducer? A. rectangles B. squares C. wedges D. circles

D. Annular array transducers have piezoelectric crystals that are donut or ring shaped. They are arranged as a collection of concentric rings.

How are the piezoelectric crystals of a linear phased array transducer fired? A. in a single specific pattern B. in order, from top to bottom C. at exactly the same time D. at almost exactly the same time

D. To steer and focus the ultrasound beam that a linear phased array transducer produces the PZT crystals are excited by electronic pulses at almost the same time. Only billionths of seconds separate the electronic pulses that strike the PZT crystal in the transducer.

With A-mode, what is displayed on the x-axis?

Depth of the reflector

With M-mode, what is displayed on the y-axis?

Depth of the reflector

Foci exist at multiple depths as an ultrasound beam propagates through the body.

False. A standard mechanical transducer cannot focus at multiple depths or provide for variable or user-selectable focal depths. Mechanical transducers support only a single, unalterable focal depth.

True or False ? The "curved pattern" of delays in the electrical spikes used in a linear phase array transducer focuses the beam during reception.

False. Focusing using time delays of the electrical spikes is a form of transmit, not receive, focusing.

What is the only display mode that provides information regarding reflector motion with respect to time?

M-mode

With B-mode, which axis is related to the strength of the reflection?

The z-axis is related to reflection strength