Chapter 11 Display Modes Flashcards
what imaging mode is
x-axis = time of flight
y-axis = amplitude
A-mode
which imaging mode accurately displays reflector depth?
A-mode
it is used in ophthalmology, req precise measures of depth and thickness
which imaging mode displays a single jagged line of varying heights
A-mode
x-axis = reflector depth
y-axis = echo amplitude
stronger reflectors=higher spikes= time of flight
with B-mode, which axis is the strength of the reflection input?
x
y
z
z- axis
which imaging mod places dots of dissimilar gray scale on the display
B-mode
brightness mode
The mode that produces lines related to the changing position of reflectors in the body with respect to time is called____
M- mode
is the only display that provides information regarding reflector position in relation to time
Which of the following do the x-axis of a B-mod, the y-axis of an M-mod and the x-axis of an A-mode all relate?
x-axis of B-mode & A-mode
y-axis of M-mode ========
REFLECTOR DEPTH
reflector depth is determined by time of flight
time of flight is
length of time form pulse creation to pulse reception
directly related to depth
depth is calculated by
depth (mm) = 1.54 mm/us * go return time / 2
what is 13-microsecond rule?
every 1cm of depth in tissue 13 us of go return time can be calculated
with these transducers us beam is STEERED by a motor, a rotating reflecting mirror or a similar device
mechanical tx
annular phased array tx
(mechanical steering)
these transducers FOCUS the ultrasound beam electronically
linear switched array
linear phased array
annular phased array
convex or curvilinear array
what tx is focused with an acoustic lens, mirror or by milling PZT in a curved shape?
mechanical tx
linear switched array tx
convex or curvilinear tx
acoustic beams can be focused similar to light waves
mechanical tx (t/f) the ultrasound beam is directed in mamy different directions to create an imaging plane
true
mechanical tx = active element aimed in several directions in order to make 2D image
without steering only a single B-mode line would exist
mechanical tx (t/f) the ultrasound beam is not focused electronically
true
mechanical focusing =
1. acoustic lens
2. curved PZT crystal
mechanical tx (t/f) there is communication between the pulsar of the us system and the piezoelectic crystal of the tx
true
wire is necessary to connect electronic beam former to PZT and send data back to receiver
mechanical tx (t/f) Foci exist @ multiple depths as an us beam propagates through the body
false
mechanical tx = 1 unalterable focal depth
which of the following statements are associated with phased array transducers lens multi-focused mirror adjustable external
adjustable
multi-focused
the minimum number of active elements in a mechanical transducer is
1
imaging plane in constructed by mechanically steering the 1 PZT with a motor
which best describes the elements in a linear phased array transducer?
(shape )
(how many)
(and width)
rectangular
100-200 elements
width of 1/4 to 1/2 wavelenght thick
t/f
phased array tx direct us pulses in many directions to create a two dimensional image
true
linear curvilinear = electronic steering
annular and phased array = mechanically
how are the piezoelectric crystals of a linear phased array tx fired
to steer and focus a linear array PZT are excited by electronic pulse at almost exactly the same time.
The pattern of electrical signals exciting the piezoelectric crystals of a linear phased array transducer
typically changes from one acoustic pulse to the next
changes every 4th or 5th acousitic pulse
changes only whenthe max imaging depth changes
none of the above
electrical signal patterns exciting the PZT of a linear phased array tx changes from one pulse to the next
the electrical patterns determine the direction and focusing of ea acoustic pulse. Each sound wave is directed in a slightly diff direction to create a 2D imaging plane
thus the electric signals vary for ea acoustic pulse
