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PRE 1 Chapter 28
Recorded Detail
| Question | Answer |
|---|---|
| Name 4 things recorded detail includes? | sharpness detail visibility visibility of detail |
| True or false recorded detail is the distinctness of the radiographic image margins? | true |
| Define recorded detail | degree of geometric sharpness or accuracy of the structural lines actually recorded on the image. |
| name 4 things recorded detail also refers to | definition sharpness spatial resoltion detail |
| What is Acutance? | the abruptness of the boundary b/t the detail and its surroundings |
| what is resolution | the ability of the image receptor to produce a separate image of closely spaced small objects and visually distinguish them |
| Digital imaging recorded detail is determined primarily by what? | matrix size, pixel size, gray scale bit depth. (x,y,z axes) |
| what is spatial frequency describes as in terms of digital imaging recorded detail? | high and low |
| short wavelength signal (high frequency)= | high resolution (pairs of lines can be visualized very close together) |
| longer wavelength signal(low frequency) = | low resolution (pairs of lines are farther apart) |
| What is the digital imaging spatial resolution measurement PSF mean? | point spread function |
| What is the digital imaging spatial resolution measurementLSF mean? | line spread function |
| What is the digital imaging spatial resolution measurement MTF mean? | modulation transfer function |
| true or false system noise is a digital imaging spatial resolution measurement ? | true |
| true or false good detail always exist, even when technique is poor? | true |
| Do all images have more or less recorded detail than the actual object? | less |
| Can a focal spot image detail smaller the same size or larger than itself ? | same size or larger but not smaller |
| What presents the best visible image? | short scale high contrast |
| What does penumbra mean? | unsharpness |
| what does umbra mean? | sharp image |
| What does PSF measure? | it measures the penumbra as well as quantifying spatial resolution |
| What does spatial resolution improve with? | reduction of screen blur, motion blur, geometric blur |
| what is spatial resolution | 1. one of the geometric properties image quality 2. the degree of Geometric sharpness or accuracy of structural lines actually recorded in the image 3. Also referred to as detail |
| when is spatial resolution higher? | when 2 objects can be demostrated to be smaller or closer together |
| what does gray scale represent? | depth |
| what does x-y matrix represent? | spatial resolution |
| what is the bit depth formula? | (2^). ( ^=bit number ) |
| What does PSF, LSF and ESF all express? | boundaries of an image |
| High spatial resolution represents a___________ frequency signal that is capable of imaging ______________ objects | Higher smaller |
| Low spatial resolution represents a ___________ frequency signal that can only image____________objects | Lower larger |
| MTF - Modulation Transfer Function is sometimes called what? | fidelity |
| what does MTF measure? | accuracy of the image compared to the original object on a scale of 0-1 |
| On the MTF scale what does 0 and 1 mean? | 0 means no signal no image 1 means high signal high fidelity |
| as spatial frequency ______________ MTF ____________________? | increase , decrease |
| what is radiographic noise? | Undesirable fluctuation in the optical density of an image or random audible or visitable disturbance that obscures information |
| What are three components of noise? | Film graininess( inherent) structural mottle (inherent) quantum mottle |
| what causes film graininess? | random distribution in size and space of the silver halide crystals in the emulsion |
| what causes structure mottle? | caused by phosphor when making the intensifying screens |
| what causes quantum mottle? | nature or random audible or visible disturbances that obscure information |
| of the 3 components of noise which is under the cont of the RT? | quantum mottle |
| what is noise ? | background information that the IR receives |
| if noise level __________ recorded detail______________? | rises degrades |
| what do we do to improve recorded detail? | Eliminate motion reduce OID reduced focal spot size reduce intensifying screen phosphorus size and concentration increased SID |
| What does distance include | |
| What is the most important facts in establishing the level of resolution for recorded detai? | Geometry of the beam |
| SID= SOD= OID= | SOD+OID SID- OID SID-SOD |
| Resolution is improved when OID is DECREASED OID increases -----resolution ________ SID increases -----resolution_________ SID decreases-----resolution _________ | decrease increase decrease |
| OID is adjusted _________ SID adjusted ___________ | first second |
| what is the focal spots major controller? | image resolution through its effect on penumbra |
| what is the formula for width of penumbra? | P= FSS x OID -------------- SOD |
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knt5411
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