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SPI Review 13
Two-Dimensional Imaging
| Question | Answer |
|---|---|
| 2 D images may also be called what ? | B- scan or B-mode |
| What is produced from multiple ultrasound pulses transmitted into the body in different directions? | A 2-D image |
| With mechanical transducer, what type of crystal(s) are used? | one disc-shaped element |
| What steers a mechanical transducer? | motor |
| What type of focusing is used with a mechanic transducer? | Conventional or Fixed |
| With a mechanic transducer, what focuses the beam at a specific depth? | Curvature (internal) of the PZT or Acoustic lens (external) |
| What planes does focusing occur with with mechanical transducers? | horizontal and vertical planes |
| How would focal depth be changed with a mechanical transducer? | Changes transducers |
| What is the image shape of a mechanical transducer? | sector (fan) |
| With a mechanical transducer scan lines spread apart creating _________ at _____________ depths | gaps , greater |
| What happens to an image with a defective crystal in a mechanical transducer? | destroys the entire image |
| A collections of active elements in a single transducer is called what ? | Array |
| A single slab of PZT cut into separate pieces is called what ? | Elements |
| The combination of the electronic circuity, the wire, and the element is called what? | Channel |
| A group of ringed elements with a common center is called what ? | annular array |
| A collection of elements in a line is called what ? | Linear array |
| What are the two types of linear arrays ? | Linear switched and linear phased array |
| What is another name for a linear switched array? | Linear sequential |
| Linear array transducers are _______________, with approximately ____________ rectangular shape elements arranged in a line. | large, 200 |
| With a linear array transducer, a few elements (3-10) are fired at exactly the same time to create what ? This improves what ? | a narrow directional beam, lateral resolution |
| What type of steering is used with linear array transducers? | None |
| With a linear array transducer, pulses are sent down in ___________________ lines, and remain equally spaced at all _____________. There are no _________ between lines. | parallel, depths, gaps |
| What shape is the image with a linear array transducer ? | rectangular no wider than the transducer |
| What affect does a defective crystal have on the image with a linear array transducer? | drop out extending from superficial to deep. |
| What type of array means adjustable focus or multi-focus that is achieved electronically? | phased array |
| Phased array transducers have approximately _____________ rectangular shapes elements arrange in a line. | 200 |
| With phased array transducers a collections of pulses are delivered to ___________ of the transducers elements in various patterns for each sound pulse. | may or all |
| Focusing and steering are _______________ with phased array transducers. | electronic |
| The phasing patterns steer and focus the sound beam during _____________. | transmission |
| What is the image shape of an array transducer? | sector |
| With phased array transducers their are miniscule time delays called ____________. These delays are between electronic pulses delivered to the individual ______________. | phase delays, array elements |
| The phase delays are so small they are fired nearly __________________________. | simultaneously |
| Approximately how long are they phase delays? | 10ns |
| What happens to a phased array transducer with an defective crystal ? | the steering and focusing becomes erratic |
| In phased array transducers an electronic slope creates what ? | beam steering |
| In phased array transducers an electronic curvature creates what ? | Beam transmit focusing |
| The _______________ creates the electronic patterns and delays in phased array transducers. | Beam former |
| Phase delays during reception can also be applied to the electronic signals from the transducer called what ? | Dynamic Receive Focusing |
| Dynamic Receive focusing provides focusing at many ___________ during ____________. | depths, reception |
| What type of phased array has crystals that are concentric rings cut from the same circular slab of PZT that looks like a bulls eye target/ | Annular Phased Array |
| Annular phased array transducers have a _________ number of ___________ shaped elements. | small, ring |
| With annular phased array transducers selected focal zones, use inner crystals for _________ regions and outer crystals for _________ regions. | shallow, deep |
| With annular phased array transducers small diameter rings have a shallow focus but ______________ rapidly in the fa field | diverge |
| With annular phased array transducers large diameter rings have a ________________. | deep focal depth |
| What is the image shape for annular phased array transducers? | pointed, fan or sector shaped |
| Annular Phased Array transducers use what type of focusing ? | multi-focusing |
| Multi-focusing provides focusing in all ____________ at all ___________. | Planes, depths |
| Mult-focusing gives optimal ____________ resolution at all _____________through out an image. | lateral, depths |
| Multi-focusing also makes a thin slice where the beam is small, this is known as what ? | elevational resolution |
| How are annular phased arrays steered ? | mechanically |
| what type of phased array is the only one that is mechanically steered? | annular phased array |
| what affect does a defective crystal have on am image? | horizontal band of drop out (side to side ) |
| Transmitting multiple pulses down a single scan line indicates what ? | multi-focusing or m-mode (depth vs time) |
| What type of array has piezoelectric crystals arranged in a curve to provide a natural sector image? | Curvilinear Array |
| Curvilinear arrays may be _________ or _______ like linear arrays. | sequential or phased |
| what does is the shape of an image produced by a curvilinear array? | blunted sector |
| what describes the area of contact between the transducer and the skin? | acoustic footprint |
| What curvilinear array has a large footprint? small? | Curvilinear Sequential -large Curvilinear Phased-small |
| 2-D array transducers create what type of images? | 3D-4D images |
| 3D imaging more accurately measures ____________ of structures. | volume |
| Curvilinear arrays have approximately _________ rectangular shaped elements. | 200 |
| 2D arrays transducers may contain ______________ of elements. | thousands |
| 4 d imaging is _________________ 3d imaging. | real time |
| 3d image quality is determined by the number ____________ | slices |
| ____________ arrays contain more elements side to side than up and down. | 1 1/2 |
| ________________ arrays contain the same amount of elements in up and down and side to side directions | 2d |
| 1 1/2 dimensional arrays allow focusing in the plan of the image. This makes a thinner slice which improves what ? | elevational resolution |
| what array transducer combine linear sequential and linear phased array technologies ? | Vector arrays |
| what is the image shape of a vector array? | trapezoidal or expanded view |
| Expanded view is especially useful when imaging what ? | superficial structures and large organs |
| What type of transducers are less useful with superficial structures? | sector |
| Vector arrays have a ___________ footprint than linear arrays, | smaller |
Created by:
dawncoffield