FInal part I Flashcards
- 25 million Hz, another way to write it?
2.5 x 10 ^ 7 or 25MHz
- What do we call a sound that is below the audible range?
Infrasound
- Know about which items are determined by the sound source
Frequency, Period, amplitude, intensity, power
- Which would be determined by medium and sound
Wavelength
- Determined only by the medium?
Propagation speed
- Acoustic variables?
Density, Distance, Pressure
- Going to have some choices for frequency and which ones has the longest wave length
Lowest frequency has the longest wavelength.
- If the intensity remains the same, the power is doubled, what happens to beam area?
Doubles. I = P/A
- What term describes the start of the pulse to the end of the pulse?
Pulse duration
- What kind of scale has dB, mathematical representation?
Logarithmic, relative scale that requires two intensities.
- Every 3 dB means the intensity will do what?
Double
- Initial intensity is less than normal intensity the gain is what?
Positive
- Rayleigh scattering is related to?
Frequency to the 4th.
- In soft tissue, attenuation coefficient is directly related to what?
Frequency
- Lots of questions on attenuation and speed? Which media will have the greatest attenuation and which doesn’t
Air>bone>muscle >soft tissue>blood>water
- 2 PZT, same material, thicker will make a pulse transducer with?
Lower frequency and slower speeds
- PZT exceeds the curie point what happens to the PZT?
Depolarization
- What are the other names for PZT
Ceramic,active element, crystal, lead zirconate titanate
- Which component of the transducer reduces the ringing of the pulse?
Backing material
- Which crystal will produce sound with the lowest frequency?
Thicker
- Damping material improves what resolution?
Longitudinal resolution page 126 question 9 on the Q and A (Harley S.)
- Damping material improves what resolution?
Longitudinal resolution page 126 question 9 on the Q and Q (Harley S.)
- If the frequency of the electrical citation of the voltage in a pulsed wave transducer is 6 hertz, what is the operating frequency of the transducer?
In pulsed wave transducers, the frequency of sound is not determined by the electrical signal.
- Impedance of a transducer of the active element is … rayls, to the skin is …. Rayls, what would be the acceptable matching layer?
Between the PZT and skin.
24.. Which transducer component has a thin barrier of cork or rubber and isolates the internal components from the transducers case
Acoustic Insulator (JL p 115)
- Which component of trans increases the efficiency of sound energy transfer of the active element in the body
Maching layer
- Frequency and near zone length are related in what way?
directly
- Two trans have the same diameter the first probe has a 6Mhz frequency and second has 8Mhz freq which beam will have a shallower focus
6 MHz, smaller diameter, lower frequency
- Which of the following probes will create a beam with the least divergence
. For least divergence we will see larger diameter crystals and higher frequency p 140 box
- Which probe will have more divergence
A probe that has a smaller diameter crystal and a low frequency will create more divergence pg 140 box
- What determines the freq of sound created by a pulsed wave transducer?
The active element the speed of sound in PZT and the thickness of the PZT
- What determines the focal length of sound beam
The characteristics of the active element, transducer diameter and the freq of sound
- Which of the transducer has the best lateral resolution in the far field
Larger diameter crystals improve lateral resolution in the far field p 139
- Sound beam is created by round PZT of diameter of 10mm the focal depth is 8cm what diameter is the sound beam at the depth of 8cm
a. 5mm the diameter is half at the focal depth of 8. Because it is in the middle p 134
- Lateral resolution need to know the other names for it which ones belong and which ones
lateral angular transverse auimuthal. It is the ability to distinctly identify two structures that are very close together when they are side by side. P 151
- Lateral resolution is what to the beam?
Perpendicular p 151
- Know about characteristics of lateral resolution
a. –is determined by width of the sound beam narrower beams have better resolution. Is best at foucus where beam is narrowest Lateral resolution= beam diameter.
- Several different methods are used to describe us beam intensity these different methods important in what kind of studies?
Study of bioeffects p 70
- When reporting a beams intensity at the location where it is maximum is referred to as what
spatial peak intensity pg 70
- What are units for intensity
W/cm2
- What is measured where intensity is max and averaged over transit time
Sppa spatial peak pulse average. P73
- Intensity is maximum and average over all time, transmit and receive?
Spta spatial peak temporal average p 73
- Which intensity is measure over the entire cross-section of crossbeam and time?
Sata spatial average temporal average p 73
- All of the terms that mean the same as normal incidence?
PORN perpendicular orthogonal right angle nighty degrees p 91
- What is the sound beam before it hits the boundary?
Incident intensity p 92
- The portion of the incident intensity after striking the boundary continues on what is that called?
Transmitted intensity p 92
- The half value layer thickness depends on which factors
medium and the frequency of sound p87
- If we have normal incidence that means that the sound beam strikes the boundary at how many degrees
90 degrees see question 38 p 91
- Sound waves with an intensity with 50 w/cm2, strikes back completely, what is the intensity reflection coefficient?
100percent p 94 Q2
- Sound wave strikes the same intensity 50 wcm2 totally reflected what is the reflected intensity?
50w/cm^2
- If the intensity reflection coefficient 99.9%, what percent is transmitted into the body?
.1 p99
- W normal incidence reflection depends upon different what? What do you have to have normal incidence
Impedance difference between the two media on either side of a boundary p 98
- What type of incidence do we not know anything about?
Oblique
- Specular reflections arise when the interface is what?
Smooth
- 2 waves travel through the medium at the same time and arrive at the same time what event takes place
Interference
- Which will create fastest speed of sound?
Thinner PZT, higher frequency
- Transmission with a bend is what?
Refraction
- If we have oblique incidence and different speeds, what will occur?
Refraction p 103
- What does snells law describe?
Refraction
- Sound waves strike a boundary at normal incidence the impedance of the media are identical what percent of the sound wave is refracted
None will reflect reflections don’t happen if no impedance difference p95
- 2 waves travel through the medium at the same time and arrive at the same time what event takes place
interference
- Which will create fastest speed of sound?
Thinner PZT, higher frequency
- 3MHz through 2 medium, attenuation 5 dB in a, 6db in b, what is the total attenuation of the sound beam as it travel through both media?
11dB
- Which are of the following are considered contributors to attenuation and which is the most important of those contributors
Reflection scattering and absorption p 81
Absorption p 84
- As path length increases and attenuation coefficient in soft tissue does what as well
remains the same (JL p 89 #13)
- Attenuation in soft tissue is less than which of the following?
Which attenuates more than soft tissue … muscle bone lung and air p 86
- Impedance is a characteristic of what?
Reflection p 88
- Reflections occur if only the 2 medium at the boundary have different what?
impedances p 96 from Q&A
- Low freq trans is best at imaging what type of structures
deep
q68. Ability to distinguish to objects close together is what?
When parallel its axial when side by side its lateral
resolution
- Which of the following is the best to image the thyroid
High freq probe 7-9 Mhz
- What is the best estimate for attenuation coefficient for sound traveling in soft tissue
One half the frequency p 85 atten coef = freq /2
- Attenuation is determined by what 2 factors
Path length and frequency of sound p 80
- Know what contributes to attenuation
Reflection, scattering and absorption (JL p81)
- When a boundary is rough the reflected sound is disorganized and random what is that called
Diffuse or backscatter
- Time of flight is known, what else can you determine?
We can know the reflector depth and the total distance traveled p 108
- When one reflector is 2X as deep as the other reflector, time of flight for deeper reflector?
twice as long
- Sound wave is created by transducer, reflection off and returns, 10 cm depth, 2 sec time
10cm
20cm (time of flight)/ 2s = 10cm
JL ESP bottom of 52
- Time needed for a pulse to travel from a transducer to the reflector is called a what?
Go return time and or time of flight p 107
- Sound wave is created by transducer, reflection returns is 52microseconds, reflector depth?
4cm p 108
- Max imaging depth is 4 cm, go to 8 cm, what happens to PRP?
It gets longer p 109
- Freq increases the numerical value of LARD res does what?
decrease
- Go return is 39 microsecondss, total distance traveled?
a. 6cm p 108
- Axial res deals with structures that are what to the sound beam
Parallel
- 2 different transducer different pulse, 5 MHz, which will more likely to create better image in regards to axial resolution
Similar Question #10, pg 150
- Conservation of energy
Pg 97, 99
- Which one has less biological effects focus or unfocus
Focus
