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LRA 221 CH 4
Photostimulable Phosphor Image Capture
| Question | Answer |
|---|---|
| What is PSP backed by? And what does it absorb? | a thin sheet of aluminum or lead that absorbs backscatter X-ray photons |
| What is Felt Material | antistatic material ; designed to reduce or prevent the buildup of static electricity |
| What is an ACTIVE LAYER of an imaging plate? | a layer of photostimulable phosphor that “traps” electrons during exposure |
| What is a COLOR LAYER of an imaging plate? | between the active layer and the support layer, which absorbs the stimulating light but reflects emitted light. |
| What does a REFLECTIVE LAYER do? | sends light in a forward direction when released in the cassette reader. |
| What is the purpose of the barcode layer? | allows the technologist to match the image information with the patient-identifying barcode on the examination request |
| The PHOSPHOR LAYER is made up of what type of Phosphor? | usually made of phosphors from the barium fluorohalide family |
| When the imaging plate is irradiated, stimulated electrons enter what layer? | PHOSPHOR/ACTIVE LAYER |
| What happens during laser beam formation? | a laser emits a strong and focused beam of light by exciting atoms or molecules in the device |
| What is COHERENT LIGHT? And which way do the photons travel? | Light amplification by stimulated emission of radiation ; all of the photons are traveling in the same direction at the same frequency. |
| What does the OPTICAL MIRROR do? | ensure that the beam is positioned consistently and directs the laser beam to the surface of the imaging plate |
| What is the typical cassette throughput? | # of cassettes that can be processed within a certain time frame which is 50 per hour |
| What is digitization? | process of converting analog info into a digital format that can be stored, manipulated, and transmitted using computers or electronic devices |
| What is the wavelength of a PSP resolution? | 633 nanometers |
| What type of pattern does the laser scan an imaging plate? | raster scanning pattern ehich is a zigzag motion |
| Define translation | the movement of the imaging plate through the reader because it moves in a parallel manner at a certain rate |
| What determines PSP resolution? | phosphor layer thickness and pixel size |
| How are PSP imaging plates erased? | flooding it with light to remove any electrons still trapped after the initial plate reading |
| What is spatial resolution? | The amount of detail present in any image |
| What is image misrepresentation? | the act of altering or manipulating an image in a way that distorts or misrepresents the original content |
| What does kVp do? | control penetration and tissue type |
| The k-edge of a phosphor imaging plate ranges from? | 30-50 keV and 60-110kVp |
| What is the range of kVps that can be used in PSP systems? | 45-120 |
| What is mAs selected for? | number of photons required for the body part to be imaged |
| What will happen to the image if insufficient light is produced by a PSP plate? | the image will be grainy, quantum mottle |
| What is quantum mottle caused by? | low #s of photons reaching the IR, insufficient light |
| What should be considered for selecting a PSP plate? | type and size |
| What is the outcome of HIGH # of pixels in a matrix? | The more pixels there are, the greater the image resolution for a fixed field of view |
| Why is it more critical to use a grid in PSP examinations than it is in film/screen radiography? | PSP systems are more sensitive to scatter radiation |
| Define grid frequency? | the number of grid lines per centimeter or inch |
| Define grid ratio? | The relationship between the height of the lead strips and the space between the lead strips |
| Which grid requires more critical beam centering? | focus grid |
| What is the benefit of collimating small? | decrease patient dose |
| Shuttering is a post exposure image manipulation technique that is added to the screen image (T/F) | true |
| Using personal markers adds credibility to a technologist expertise (T/F) | true |
| What is exposure index (indicator) measure? | the amount of radiation recieved by the image receptor |
| What causes cracks in the imaging plate? | As the imaging plate ages, it becomes prone to cracks from the action of removing and replacing the imaging plate within the reader. |
| What type of artifacts are intermittent extraneous lines? | plate reader |
| PSP phosphor speed and radiographic film speed are always equal? (T/F) | False |
| Does a PSP plate require periodic erasure? | PSP readers have an erasure mode that allows the surface of the imaging plate to be scanned without recoding the generated signal. |
| Is less kVp needed for conventional radiography or PSP systems? | Sufficient kVp is needed to penetrate the body part; however, higher kVp values can be used, allowing for lower mAs values. |
| Grid lines interfere with an image?(T/F) | True |
| It is acceptable to replace collimation with shuttering?(T/F) | False |
| Images should be marked with only computerized markers?(T/F) | False; conventional lead markers |
Created by:
nishaat