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chap31 digital image
| Question | Answer |
|---|---|
| 3 classifications of artifacts in screen-film imaging | processing exposure handling/storage |
| 3 classifications of artifacts in digital imaging | image receptor software object |
| digital image receptors can suffer from | rough handling scratches and dust |
| digital image receptors have unique artifacts associated with | pixel failure |
| QC should include ----- to reduce artifact appearance and help prevent failure | regular documentation of imaging frequency, imaging performance, and the physical condition of each IP |
| the appearance of --- occurs because of incomplete erasure of a previous image on a computed radiography IP | ghost images |
| Lossy compression can compress the raw data even more than ---- but the lossy compression can loss data | lossless compression |
| Histogram is also known as a | look up table |
| ---- images are manipulated into "for presentation" images that the radiologic technologst can use for QC and for interpretation by the radiologist | "for processing" |
| --- is the raw data that has been preprocessed | "For processing" |
| Flatfielding is a ---- tool | preprocessing |
| data compression takes advanage of redundancy of data, as occurs with exposure to the raw x-ray beam when all values are the same. Such compression techniques are described as---- | lossless or lossy |
| an image file that is compressed in a --- mode is one that can be reconstructed to be the exact same as the original image | lossless |
| Lossless compression reduces the date file to --- of the original file. | 10-50% |
| ---- compression cannot be used for large files because transmission time and data manipulation time can still be unaccetable | lossless |
| Lossless compression up to ---- generally is considered acceptable and helpful in digital image management | 3:1 |
| Image receptor artifacts in ----: dust, dirt, scratches from IP, pixel malfunction, ghost images | digital |
| -- does not break down like a light bulb (no radiation fatique) | IP |
| debris on IR in DR can be confused wih --- | foreign bodies |
| dead pixels- | pixels that do not contain any raw data. Will go through interpolation |
| Lossy can compress up to --- fast teleraiography | 100:1 |
| Moire' effect | (on registry) can get it from grid lines and short exposure where there is not enough pixel data |
| histograms | For example. How often the frequency of lung tissue occurs of a PA chest of chest x rays |
| average digital film size ---mammography has 50MB | 20MB |
| --- compression is best for medial imaging | lossless |
| pixels that need ---- have no data | interpolation |
| Interpolation | completing a picture by creating info for pixels that do not have any |
| ---- gives a uniform pixel look to counteract the anode heel affect (Pixel contains raw data ) | flatfielding |
| ---- come from incomplete erasure,(exposure to environmental radiation) | ghosting artifacts |
| -----: fills in gap colors of pixes, makes a calculated guess, creates data that wasn't there | interpolation |
| line artifacts can come from | dirt collected in CR reader or glue |
| a --- is a graph of frequency of occurrence versus digital value intervals | histogram |
| partitioning | allows two or more images to be projected on a single IP |
| software artifacts | histograms range/scaling image compression |
| Object artifacts | patient positioning collimator/ partition back scatter |
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654371161