-
What is the source of harmonic frquencies in the bubble study?
The bubbles, as they interact with the passage of a high pressure sound wave.
-
What is the source of the harmonic frequencies in THI?
The tissue as it interacts with a high pressure sound wave.
-
How are harmonic generated?
As a low pressure sound wave passes thru soft tissue a sinusoidal wave is generated ina relatively pure wave. As the pressure is increased, differences in a progagation speed in various parts of the sound wave are introduced. In areas of high pressure, the sound speed increases, while in low pressure regions it decreases. This changes the shape of the once-sinusoidal wave, and also gives rise to the harmonic frequencies.
-
Compare the terms linear and non-linear?
When low pressure fundamental frequencies are used, fundamental frequencies echoes are returned . This is linear propagation. When high pressure fundamental fequencies are used various harmonic frequencies are generated. This is non-linear propagation.
-
Why are 3rd and 4th harmonic frequencies not currently used?
As subsequent harmonics are significantly weaker than lower harmonics, they cannot be currently processed.
-
What factors does the generation of harmonic depend?
- a) accoustic pressure
- b) frequency
- c) non-linearity co-efficient
- d) density
- e) velocity of medium
- f) distance of propagation
- e) all of the above
-
In which regions of the beam are the harmonics produced?
In the middle regions of the image. There is insufficient energy in the beam close to the Tx and in the distal far field to generate harmonics.
-
State the benefits of harmonic imaging?
- a) decreased clutter (gating and siding lobes)
- b) decreased reverb artifact
- c) reduced acoustic noise
- d) less fill-in from cystic structures
- e)improved lateral and axial resolution
- f) improved imaging in obese patients
- g) all of the above
-
Why are longer pulse lengths generally used in non-pulse inversion harmonics?
Both transmitted and received bandwidths must "fit" within the bandwidth. In oder to cause a narrowing of these bandwidths, the pulse lengths are increased.
-
What is the down side of using non-pulse inversion harmonics?
Because pulse lengths are increased to reduce bandwidths, there is a concomitant reduction in axial resolution.
-
Under what conditions is transient echo imaging especially useful?
Where blood flow velocites are very low.
-
In transient echo imaging, what causes the choatic appearance the helps track blood flow?
The disintegration of the gas bubbles.
-
Describe the basic process of pulse inversion harmonics.
In pulse inversion harmonics two pulses are generated. The second pulse is an inversion of the first. Another way to explain it (180 degrees to the first). Echoes received form the two-equal-but-opposite pulses are summed and cancelled out. The harmonics from each of the two pulses are summed and constructively interfere improving the harmonic signal.
-
What is given up when using each of the two types of harmonics?
- regular harmonics-->axial resolution is worse then with pulse inversion.
- pulsed inversion--> frame rate is lower due to the increased dwell time.
-
Which generates stronger harmonics, contrast agents, or tissue harmonic imaging?
contrast agents.
-
One type of harmonics is considered a filtering technique and the other a subtraction technique. Which is which?
- Regular, non-pulse inversion is considered a filtering technique because the fundamental is filtered out leaving only the harmonics.
- Pulse inversion is considered a subtraction technique because the fundamental frequencies are removed form the bandwidth by cancellation.
-
What is 3D U/S? compare to 2D?
Collection, storage and display of echoes in 3D (axial, lateral, and elevational)
-
What is 4D U/S?
4D adds the additional dimension of time. It is just real time 3D.
-
Some have said that 2D has a 3rd non-spatial dimension. What are they talking about?
Brightness.
-
What are three ways of displaying 3D information?
- Multiplanar Reformating-->viewing single plane using perpendicular planes anywhere in the 3D volume surface rendering-->depicts the surface objects for display
- volume rendering-->a 2D image based on inside the 3D volume.
-
How does 3D and 4D change the way sonographers work?
We can obtain the volume with not as much regard for correct Tx placement. They can obtain desired planes at a computer work station. There is theoretically less scanning time but more time at computer work stations. It also alters our perception of planes;although we have built up mental 3D images when doing 2D exams.
-
What are the limitations of doing a 3D/4D? What has it been slow to be accepted?
- a) time consuming to learn
- b) requires huge amounts of computer memory
- c) lack of orthogonal scan planes
- d) slower frame rates
- e) limited time scans
- f) long comutational times
- g) many factors contribute to the echo induced signal making some data manipulations difficult to apply
-
What are voxels?
Are 3-Dimensional pixels. Pixels are 2-Dimensional.
-
What is interpolation? Why is it neccessary?
Interpolation is a mathematical calculation of a pixel value even though the U/S beam has not passed thru a corresponding volume of tissue. If interpolation doesn't occur the pixel corresponding to a non-filled- in voxel will be blank or black. So this does no occur adjacent voxels are evaluated and then an averaged value is inserted in the "empty" voxel.
-
How may U/S change the way we operate. This has already happened to some extent in echocardiography.
3D/4D will or already has changed the way we operate. A shorter time spent collecting the data (scanning) and greater time manipulating the data. This may be a partial solution to repetative strain. We may become just as adept at manipulating data as they now are at acquiring data.
-
Proper power settings. What happens at 100% and 0%
- Too high= implosion
- Too low= static
-
Increased freuency = increased or decreased resolution?
increased
-
What is the basic idea of harmonics?
To transmit a lower frequency (penetrate) and to receive at a higher frequency (detail).
-
Regular harmonics must fit into the Tx bandwidth, how is this accomplished?
The SPL is lengthened causing one pulse for each echo train.
-
If fundamental frequencies cancel each other out, What happens to harmonic frequencies?
They are added together.
-
Shorter Pulse Length with increase or decrease the frame rate and why?
It will reduce the frame rate becuase there is two pulses instead of one.
-
Becuase RBC's are a very poor reflector, the contrast agent is used to increase or decrease accoustic impedance mismatch?
INCREASE
-
What are some reasons for using RIS/PACS?
- a) escalating storage costs
- b) efficient image managment
- c) FOIP
- d) possible teleradiology
- f) image transfers
- g) distributed reports elctronically
- h) higher costs though
- i) increased spatial resolution
- j) digital storage
-
What does DICOM stand for?
Digital imaging and communciation of medicine.
-
Why do we record images?
- a) reporting physician doesn't have to scan everybody
- b)communication btw. us and doctor
- c) for comparison
- d) legal purposes
- e) all of the above
-
What does WYSIWYG stand for?
What you see is what you get.
-
How long does Polaroid development take?
- a) 90 seconds
- b) 30-60 seconds
- c) more than two minutes
- d) 15 seconds
-
What are some disadvantages of using polaroid?
- a) low quality images
- b) limited gray scale
- c) expensive
- d) difficult to obtain film
- e) all of the above
-
What lies on top of the transparency film?
single sided emulsion
-
What lies below the transparency film?
Polyester
-
What side of the transparency is the latent image on after exposure?
The emulsion side.
-
What kind of crystals in a gelatinous suspension does emulsion consist of?
Silver halide crystals
-
Emulsion is exposed to light and then through a series of chemical reactions. The regions are ___(a)____ in proportion to the intensity of ___(b)___.
- (a) is darkened
- (b) is light
-
Does emulsion provide good gray scale?
YES
-
Film processing takes how long?
90 seconds
-
Development takes?
Fixing takes?
Washing takes?
Drying takes?
- develop --22 seconds
- fix-- 22 seconds
- wash-- 20 seconds
- dry-- 26 seconds
-
Exposed grains are converted to particles of metallic silver. This happens during which part of film processing?
During the development
-
This stops the action of the developer and has preservatives and hardeners present.
The fixing
-
During this process the fixer is removed form the film. If it is not all removed it will soon have a _______ color?
Washing process. Turns a yellowish-brown color.
-
This happens when dry circulating air blows over the film?
Drying process.
-
What is Muiltiformat camera?
1,2,4,6, or 9 images on one transparency film.
-
What are some considerations with multiformat cameras?
- a) phosphor coating must be uniform
- b) flat monitor face
- c)high quality lens
- d) synchronized camera shutter with beginning of a frame
- e) If raster lines are visible, one field is shifted slighly to full in spaces.
- f) all of the above
-
What does laser stand for?
What did it replace?
- Light Amplification Emission of Radiation
- Relaced the CRT.
-
What is the diameter size of the laser beam?
0.1mm or less
-
The beam sweeps across the film in ______________ depositing information from the memory. The film then goes to the processor for developing.
Raster lines
-
Laser cameras fill in unexposed areas which on other films would be clear. This _________ our perceptions of contrast resolution. Film for this camera must be selected according to the light color emitted from the laser.
Improves
-
What are some advantages of laser cameras?
- a) multiple sources can be connected to the camera
- b) many image formats can be accomodated
- c) good spatial resolution
- d) all of the above
-
With a laser camera, the processing time takes ___ seconds?
A maximum of ___ films per hour?
Uses ________ instead of halide crystals?
Dry process is heated by the _______?
The laser places over ______ spots or pels in the area the size of a pixel?
The number of pels which are blackened in each pixel area determines the __________
- a) 90 seconds
- b) 40 films
- c) carbon
- d) laser
- e) over 4000
- f) gray shade
-
What are some of the advantages of the dry process with transparency film?
- No plumbing.
- Multiple units attached to it.
-
What does a Video Printer use to place the image on the paper?
- Impact--> poor gray scale. DONT use in U/S.Heat--> heat sensitive paper, heated scan head scans the paper line-by line causeing carbon deposition.
- Light--> photo method, a light sensitive paper is passed by a CRT and info is deposited line-by-line.
-
What are the advantages of using a Video Graphics Printer?
- a) cost
- b) convenience
- c) speed
-
What are the problems with Video Graphics printers?
Limited gray scale and less archival stability.
-
Color video Printers uses chemically treated paper scanned by a thermal head. Various colors or _______ are heated to release a gas in a particular quantity which is infused into the paper.
Ribbons.
-
In a Color Video Printer, the degree of heating determines the ________________?
Color density.
-
In a Color Video Printer, the print time is usually less than __ seconds?
90 seconds.
-
Magnetic Tape recorder is also known as ________
Half inch tape containing ________.
Dipoles are rearranged by a magnetic field from the two ____________.
Each head writes _______.
Only _____ lines per frame.
Quality ________ as tape speed __________
- a) VHS
- b) dipoles
- c) writing heads
- d) one field
- e) 240
- f) decreases
- g) increases
-
When was SVHS introduced?
How many lines involved?
Compatablility btw. VHS and SVHS is ___________
shelf life is _______
______ track is attractive.
- a) 1987
- b) 425
- c) limited
- d) two years
- e) voice
-
What are some other names for magnetic disc?
- a) Winchester disc
- b) removable cartridges
- c) floppy discs
- d) all of the above
-
Digital information in a magnetic disc is laid down magnetically in forms of __________
1's and 0's.
-
Disc are divided into_____ and ______.
Information is transfered to and from the disc via ____ and _____ heads
- a) tracks
- b) sectors
- c) read
- d) write
-
Which magnetic disc has the most storage capacity? (Megabytes)
- Floppy 0.3-4.0
- Optical disc 100-1000
- Cartridge 2.5-80
- Winchester 10-1000
-
Which of the magnetic disc has the fastest transfer rate?
Winchester is the fastest.
-
In order to record 74 minutes of info, ______ megabytes need to fit onto a ____ cm diamter disc.
The disc consists of a piece of clear _________________.
In the plastic is a series of microscopic ________.
- a) 783
- b) 12
- c) polycarbonate plastic
- d) bumps
-
The compact discs bumps are laid out in a continuous ________ pattern.
On the top layer is a reflective __________ which covers the bumps.
Then a thin layer of ______ is sprayed over top of the aluminum.
What are the dimensions of the pits?
A micron is _________ of a meter.
A nanmometer is ________ of a meter.
- a) spiral
- b) aluminun
- c) acrylic
- d) (0.5 microns x 0.83 microns x 125 nanomaters) WxLxH.
- e) one millionth
- f) one billiionth
-
What are the three main components or a CD?
- Motor
- Laser/lens
- Tracking system
-
With a CD, the laser focuses light which passes through the polycarbonate layer and reflects off the aluminum layer and detects the bumps. The light reflects differently on the bumps compared to the "valleys". The disc motor has to change speed as the laser reads from _____ to _____.
-
CD has a dye layer under the smooth reflective surface. With an unrecorded Cd, the dye is ________.
When writting a laser _______ spots where the bumps would be. This forms non-reflective areas.
The _____ laser is more powerful than the ______ laser.
- a) translucent
- b) darken
- c) write
- d) read
-
True or False; a CD cannot be over-written?
TRUE
-
Re-recordable discs have a _________ compound in them whichm when unrecorded is _________.
To record info a laser heats this compound to melting which changes its reflective characteristics.
- a) crystalline
- b) translucent
-
An erase laser can re-melt the compound, which does what?
Changes the series of bumps. ( re-writable)
-
DVD is similar to a CD but has a much _______ capacity.
DVD hold ____ times more data.
DVD have _____ layers of reflective material.
The date bumps and tracks are much ______ than on a CD.
The laser can focus through the _____ layer to get through to the ___ ___layer.
- a) larger
- b) seven
- c) several
- d) smaller
- e) first
- f) second
-
Why can DVD store more information?
- a) they have additional layers
- b) they have smaller pit lengths
- c) all of the above
-
What does the ALARA principle stand for?
As Low As Reasonably Achievable
-
True or False:
Medical benefit should be expected
Risks must be maximumized
Presently there are no assumed risks with medical U/S
-
How do we know that a risk exists?
- a) cells
- b) plants
- c) experimental animals
- d) epidermiological studies on humans
- e) studies with u/s interactions ( heat and cavitation)
-
True or False:
Cell suspensions are the same from human cells.
There have been no reports of cellular damage
It is difficult to extrapolate cellular studies to human medical situations.
- a) False. Very different
- b) False
- c) True
-
AUIM statment w/ cells
The predominant physical and biological interactions and mechanisms involved in and in vitro effect may not pertain to the invivo situation. Meaning what?
In virto effect must be regarded as a real biological effect.
-
AUIM statment w/ cells
- experiments serve as a basis for design of invivo experiments.
- Although there is a limited applicability to in vivo biological effects, such studies can disclose fundamental intercellular or intracellular interactions.
- Reports which do more should be viewed with caution.
-
True or False:
Plants are NOT useful in U/S experiments because of the gas-filled channels btw. cell walls.
This is how they study caviation.
- a) False. It's useful
- b) True. Bubble behaviour and formation.
-
Plants
The only irreversible effect on plants is ________
a) cell death
-
The Reversible effects on plants are?
- a) chromosomal abnormalities
- b) mitotic index reduction
- c) Growth rate reductions
- d) all of the above
-
True or False;
Intensity thresholds are much higher than with continuous?
TRUE
-
Name some of the animal effects:
- a) fetal weight reduction
- b) post patrum mortality
- c) fetal abnormalities
- d) focal lesion production
- d) hind limb paralysis
- e) blood flow stasis
- f) would repair enhancement
- g) tumor regression
-
What are the two mechanisms for producing bioeffects?
Heat and Mechanical
-
HEAT
True or false;
Attenuation in tissue is mostly due to absorption
Amount of heat generate depends on frequency and resolution
- a) TRUE
- b) FALSE. frequency and amplitude
-
As heating increases:
Frequency __
Amplitude __
-
Heating is significant if it is greater than ____.
Absorption coefficients are greater in bone than ________.
Therefore _______ gets special attention.
- a) two degrees
- b) soft tissues
- c) fetus
-
Possible fetal anomalies:
None of these effects have been produced at less than ___.
- a) fetal absorption or abortion
- b) microopthalmia
- c) cateract production
- d) abdominal wall abnormalities
- e) renal agensis
- f) palatal defects
- g) reduction in brain waves
- h) spinal cord defects
- i) anencephaly
- j) abnormal tooth genesis
- k) microencephaly
- l) tibial and fibular deformations
- m) amyoplasia
- n) forefoot hyperplasia
- o) 39 degrees
-
What are the three mechanical bioeffects?
- a) radiation force
- b) streaming
- c) caviatation
-
What kind of force can disrupt or deform bubble structures?
Radiation force
-
TRUE or FALSE:
Streaming is the excessive radiation force that can cause flow in an absorbing medium?
This can cause shear stress?
-
This type of cavitation is where the bubbles oscillate in response to pressure variations and can result in streaming of surrounding liquid.
Stable cavitation
-
This type of cavitation becomes so large that they collapse
Transient Cavitation
-
Transient Caviation can produce
- a) shock waves
- b) extremely high temps.
- c) light emissions in clear fluids
- d) all of the above
-
True or False:
Only effects on mammals of gas body formation is blood cell extrasvasion in inflated lung.
This does not occur at accoustic pressures less than _____
-
True or False:
MI= peak rarefactional pressure divided by the square root of the center frequency of the pulse bandwidth
This number should exceed 0.3
- a) true
- b) False. DOESNT exceed 0.3
-
True or False
TI of two or more is considered OK?
a) FALSE. Should never exceed two.
-
The TI is dependent on:
- a) frequency
- b) amplitude
- c) Intensity
- d) all of the above
-
What does TIS, TIB, and TIC stand for?
Thermal index in soft tissue, bone, and cranial tissue.
-
Does entertainment U/S have a place in this world?
FUCK NO
-
What is the maximum outout of commercially available u/S scanners?
720 mW/cm2 SPTA.
-
Which fetal tissues are suceptible to the effects of ultrasonic irradiation?
Bone is more suceptible to heating than soft tissues.
-
Rank the following from least to greatest ultrasonic energy output:
COLOR
2D
M-MODE
SPECTRAL
- a) least --> 2D
- b) M-MODE
- c) COLOR
- d) most -->SPECTRAL
-
What are the two methods of viewing an acquired image?
-
The greater the concentration of silver crystals, the _________ the image
a) darker
-
TRUE or FALSE:
Transparency film must be chemcially processed in order to be visible?
a) TRUE
-
What were some of the down falls to the multiformat camera?
- a) film could fall out of cassette system
- b) CRT light output did not remain constant over time
- c) movemnt of film relative to the lens position had to be precise if distortion was to remain with acceptable limits
- d) all of the above
-
What was a significant down side to wet processing?
The need for seperate darkroom and all of the space associated with plumbing requirments.
-
What are the three types of Video printers known as?
Frame grabbers
-
U/S scanner has two memmories
- a) RAM--> for short term storage
- b) hard drive--> for long term storage
-
True or False:
The CD Re-writable can only be recorded on once?
a) true
-
Is there chemical processing involved with color video printing?
a) no
|
|
