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SPI Review 14
Contrast, Spatial and Temporal Resolution
| Question | Answer |
|---|---|
| Visualizing a variety of grey shades in an images is what type of resolution ? | contrast |
| few gray shades has ________________ contrast resolution | poor |
| many gray shads has ___________________ contrast resolution | good |
| Visualizing detail in an image affected by axial resolution, line density, monitor as well as other factors is what type of resolution? | Spatial Resolution |
| Limited image detail has ____________ spatial resolution ? | poor |
| Fine image detail has ______________spatial resolution? | good |
| A series of frames displayed in rapid sequence to give the impression of constant motion, a movie. | Real-time imaging |
| The ability to accurately locate moving structures at any particular instant in time. | temporal resolution |
| Temporal resolution depends only upon ______________________. | Frame Rate |
| _____________ images per second improves temporal resolution. | more |
| frame rate has unites of what ? | Hertz |
| Typical value for frame rate is what ? | 20Hz-100Hz |
| Frame rate is determined by what two settings? | Imaging depth and # of pulses per image. |
| Frame rate is limited by what 2 factors? | the speed of sound in a medium and imaging depth |
| What is the fundamental limitation of temporal resolution? | Speed |
| The sonographer can adjust the ____________________. | depth of view |
| The speed of sound in a medium is a characteristic of the medium and __________________ be changed. | cannot |
| What are the 4 settings that a sonographer can control that affect temporal resolution? | maximum imaging depth, # of pulses per scan line ( multi-focus systems), sector size, line density |
| ____________ depth of view makes a frame faster and improves temporal resolution. | shallow |
| Imaging to a shallow depth requires _____________ listening. | less |
| Imaging to a greater depth of view requires __________ listening. | longer |
| If imaging depth of view is doubled, the frame rate will be _______________. | halved |
| What will create a frame with few pulses? | single focus systems |
| Single focus systems improve what ? | temporal resolution |
| Single focus systems uses _________ pulse (s) per scan line | 1 |
| Multi-focus systems use ___________ pulse (s) per scan line | multiple |
| Using multiple pulses per scan lines _________ the frame rate. | lowers |
| Multi-focus systems _____________________temporal resolution | reduces |
| Improving image quality often ___________ temporal resolution. | degrades |
| Multi-focus generally improves ______________ and degrades____________. | lateral resolution and temporal resolution |
| Smaller sector angle creates images with ___________ pulses. | fewer |
| 30 degree sectors require certain number of pulses then a 90 degrees sector image uses __________ as many pulses. | 3 times |
| Low line density images uses ____________pulses. | fewer |
| Lower line density ____________ spatial resolution . | degrades |
| Line density in a sector image is the number of scan lines per __________. | degree of sector |
| Line density in a rectangular image is the number of scan lines per _____________. | rectangular |
| Factors that shorten the time required to make each frame increases frame rate and _____________ temporal resolution. | increases |
| Factors that lengthen the time required to make a frame will reduce the frame rate and ______________temporal resolution. | reduce |
| As temporal resolution improves, image quality may _____________. | degrade |
| As temporal resolution degrades, image quality may _____________. | improve |
| Increasing the line density __________temporal resolution but improves ________________resolution. | degrades, spatial |
| Using multi-focus _____________ temporal resolution but ________________lateral resolution. | degrades, improve |
| To increase frame rate without degrading image quality can be achieved by making the color doppler box _________________ | smaller |
| With low frame rates, ________________________ physiologic events may be missed. | short duration |
| Short Duration can occur in the time ________________. | between frames |
| The time required to make a frame. | T (f) |
| T f and frame rate are _______________. | reciprocals |
| When a frame is made quickly, _____________ frames are created each second. | many |
| When a frame rate is made slowly, ____________ frames are created each second. | few |
| T (f) X FR = | 1 |
| Typical values of frame rate are what ? | 20 Hz to 100 Hz |
| Typical values of time to create a frame (T f) | 0.01 to 0.05 seconds |
Created by:
dawncoffield