pulse echo system pt 2- week 8

types of doppler:

•spectral analysis

•color Doppler

•power Doppler

6 display modes

•A mode

•B mode

•M mode

•B scan

•Real-time

•Doppler

A- MODE also known as

amplitude mode

A-MODE was original display mode for

US

A-MODE display is similar to an

oscilloscope

A-MODE is a

one-dimensional image

A-MODE has a series of

spikes

in A-MODE, each spike represents a

reflector or interface in the body

in A-MODE, the higher the spike (higher the amplitude)

the stronger the reflector

A-MODE shows

depth information

A-MODE is still used in

ophthalmic studies

B-MODE also known as

brightness mode

B-MODE is a series of

dots

in B-MODE each dot represents a

reflector or interface in the body

in B-MODE the brighter the dot,

the stronger the reflector

M- MODE also known as

motion mode

M-MODE is a •B mode operation in which the motion of the dots

is displayed across the face of the display

M-MODE is a one-dimensional image w/

respect to time

in M-MODE, straight line indicates

no reflector motion

in M-MODE, moving line indicates

motion

M-MODE is used most commonly with

heart imaging

M-MODE can be recorded on a

strip chart

in B-SCAN B mode is combined with

scanning motion

with B-SCAN, B mode dots are imaged in a

vertical line

a B-SCAN is many vertical lines placed

side by side

in B-SCAN the dots represent

depth and location or position within the body

B-SCAN forms a

2-dimensional image

two types of B scan

•static scanning

•real-time or dynamic

STATIC SCANNING also called

compound or contact scanning

with STATIC SCANNING, transducer arm is

mounted on scanning or articulated arm

in STATIC SCANNING the electronic controls in arm describe

transducer position and angle to US unit

STATIC SCANNING scanning motion is provided by the

Sonographer and image is "drawn" or "painted" on the screen

in STATIC SCANNING, ____ _____ is displayed

no motion

with STATIC SCANNING, original image was bistable until

gray scale was added

STATIC SCANNING advantage

•large field of view

3 STATIC SCANNING disadvantages

•no motion on screen

•difficult to produce quality images

•takes longer time to scan

REAL-TIME also called

Dynamic scanning

in REAL-TIME, sound beam is swept by the transducer by

mechanical or electronic means

REAL-TIME produces a series of

frames or pictures and displaying them in rapid sequence = motion picture effect

FRAME

multiple scan lines side by side

FRAME RATE is multiple frames seen

one after another

FRAME RATE is also the # of images per

second

FRAME RATE units

per sec or Hz

in FRAME RATE typically ____ frames are produced in a second (30 is the average)

10-60

with FRAME RATE, the human eye can see flickering of an image up to

15 images per second

with FRAME RATE when it is above 15, the image appears to be

moving or dynamic or real-time

LINE DENSITY is the number of

scan lines to create a single frame

•aka lines per frame

LINE DENSITY is sometimes controlled by the

Sonographer

the greater the line density,

the better the detail resolution

the _____ the line density, the better the _____ resolution

greater; better

more time is needed to create a frame with

greater line density

LINE DENSITY, for a single focus, one scan line is produced

per position

LINE DENSITY, for multi-focus, multiple scan lines are created

prior to moving to the next position

•ex: 3 focal zones = 3 scan lines

•pulse repetition frequency (PRF) is determined by the

# of focuses, line density and frame rate

•PRF = n x LPF x FR < 77,000

•PRF is also determined by the

depth of penetration

•deeper imaging =

longer waiting period to listen for returning echoes

•longer PRP =

lower PRF

if frame rate increases

PRF increases

if penetration increases

PRF decreases

if penetration increases,

frame rate decreases

if # of focuses increases,

frame rate decreases

if line density increases

frame rate decreases

TEMPORAL RESOLUTION is the ability of a display to

distinguish closely spaced events in time

with TEMPORAL RESOLUTION, if you see flicker =

poor resolution

TEMPORAL RESOLUTION improves with

increased frame rate

CODED EXCITATION utilizes ensembles of pulses to

generate a scan line

CODED EXCITATION is a decoder in the

receiving portion "interprets the code"

CODED EXCITATION result is higher intensity driving pulse and

more sensitive receiving system

HARMONICS is a type of

filtering

HARMONICS filter out the

fundamental frequency

HARMONICS improve images in 3 ways:

•primary beam is narrower (better LR)

•eliminate grating lobes

•generated beyond where some artifacts occur

•fundamental & harmonic frequencies must fit into the

overall bandwidth of the transducer

fundamental & harmonic frequencies are "crammed" into a

narrow bandwidth

•so pulse is longer

•compromises axial resolution

HARMONICS are accomplished by

pulse inversion

HARMONICS ARE ACCOMPLISHED BY PULSE INVERSION (4 things)

•uses two pulses per scan line

•second pulse is the inverse of the first

•sequences are added together to create the scan line

•improves detail resolution at the expense of temporal resolution

ELASTOGRAPHY estimates

tissue stiffness

•"imaging" palpation

•evaluating benign vs. malignant masses

•assessing viability of myocardium

ELASTOGRAPHY is an

"imaging" palpation

ELASTOGRAPHY evaluating benign vs.

malignant masses

ELASTOGRAPHY assessing viability of

myocardium

FUSION IMAGING is a combined presentation of an US image with

another imaging modality

TISSUE DOPPLER measures

movement of muscle

Three reasons to record or save images:

•a means to allow the physician to observe the exam without performing or observing

•images of follow-up exams can be compared with previous exams

•documentation for legal purposes

3 types of film:

•transparency

•thermal

•laser

TRANSPARENCY FILM required

chemical development

TRANSPARENCY FILM needs a

darkroom

in TRANSPARENCY FILM, light exposure

ruined the film

THERMAL FILM is commonly used in

offices

with THERMAL FILM, print is processed in

~ 10 seconds

with THERMAL FILM, you can adjust

brightness, contrast and sharpness

LASER FILM is

"Light Amplification by Stimulated Emission of Radiation"

LASER FILM advantages:

•superior image quality

•contrast & spatial resolution

•256 to 4096 shades of gray!

•15 or more images per film

•film size 14 x 17

•multiple users

COLOR VIDEO PRINTER is very common for printing

color Doppler images

in COLOR VIDEO PRINTER, video signal from US unit is

sent to printer and stored in computer memory

•allows for multi-format display

in COLOR VIDEO PRINTER, image is heat processed onto

chemically treated paper through 3 color ribbons

in COLOR VIDEO PRINTER, ____ ____ ____ are used

cyan, magenta and yellow are used

•all 3 together make black

in COLOR VIDEO PRINTER, paper is printed ____ times

3 times

•once for each color

VIDEO CASSETTE RECORDER (VCR) allows recording a series of images to be played back in

real-time

VIDEO CASSETTE RECORDER (VCR), •Standard VHS tapes can record

240 lines

VIDEO CASSETTE RECORDER (VCR), Super VHS tapes can record

425 lines

VIDEO CASSETTE RECORDER (VCR), along with video, also have

audio recording