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Digital radiography can be divided into two groups
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Which system uses a photostimulable storage phosphor imaging plate
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ch 25 digital rad
| Question | Answer |
|---|---|
| Digital radiography can be divided into two groups | cassette base, cassette less |
| Which system uses a photostimulable storage phosphor imaging plate | cassette base |
| T/F A cassette base system can be used in a bucky or for portables | True |
| Computed radiography is considered | indirect digital |
| Cassette-less systems are considered | direct digital |
| A system that uses a two part process involving a scintillator and a photodetector is called | indirect acquisition |
| A system that directly convert incoming x-ray photons to an electronic signal is called | Direct acquisition |
| What phosphor imaging plate is a rigid sheet with several layers that are designed to record and enhance transmission | photostimulable |
| The photostimulable phosphor imaging plates layers include | protective layer, phosphor layer,support layer, conductor layer, light shield layer,backing layer |
| Which photostimulable phosphor layer insulates the imaging plate from handling | protective layer |
| In order for CR to function, the imaging plate material must have the ability to___and____the image in formation in a usable form. | Store, release |
| The halides are approx.85%______and 15%____ | bromide, iodine |
| The most common phosphor with characteristics favorable for CR is | barium flurohalide bromide, iodides with europium activators |
| What does not release all the energy absorbed from the incident x-ray beam | Fluorohalides luminesce |
| Although some light is emitted, the phosphors retain sufficient energy in the form of a | latent image |
| The latent image is actually created by energy transfer during | photoelectric interaction |
| The latent image will lose about ___ % of its energy in __hrs | 25,8 |
| Image acquisition begins with x-ray exposure to the | imaging plate |
| Radiation exposure causes___of the imaging plate but some of the energy of the beam is also stored on the plate. | Fluorescence |
| A latent image is stored in the imaging plate, similar to a image on film, but with a | wider latitude |
| Reading the imaging plate involves a finely focused laser beam that frees the trapped____, allowing them to return to a_____ energy state | electrons,lower |
| Residual image left on the imaging plate is erased by exposure to an____ ___ to release any remaining trapped electrons | intense light |
| The___ and ____ of an imaging plate can occur in a single processor unit | reading, erasing |
| The finely focused laser beam that scans each line of the imaging plate correlates to one | line spacing or pixel dimension |
| The number of ___ determines and affects the density and contrast of an imaging system | bits/ pixels |
| During processing the CR system must determine the ____of the part and the number of____ per plate | orientation, projections |
| raw data from scanning will have a range of values related to how much__ the plate received. | radiation |
| The areas outside the collimation lines will have the ____ exposure or value. | lowest |
| The area within the collimated field will have the____ values | highest |
| T/F A marker placed outside the collimation field will appear in the processed image. | F |
| T/F There are certain expectations that need to be met when placing more than one image per plate. | T |
| T/F The plate can't be programed and then used for a number of different scanning detection patterns. | F |
| During initial processing what is created form the image data | Histogram |
| The CR system finds the useful signal by locating the _ and _ singal within the anatomical regions of interest in the image | minimum, maximum |
| T/F Image processing will provide the proper gray scale, regardless of variations in kvp and mas | T |
| The appropriate anatomical menu is selected by the body part by the _ when the imaging plate is loaded into the reading unit. | Radiographer |
| The correct anatomical menu should be selected prior to processing the image plate; otherwise the image will not process the correct_ and _. | Density, contrast |
| It is critical to adhere to uniform positioning and collimation procedures when using a CR system. | T |
| T/F The reading system must be given consistent data to analyze if it is to provide consistent diagnostic quality results. | T |
| New generation CR readers store the _ data in the workstation. | Raw |
| Many manufacturers state in their technical usage information that _ has little effect on the visualization of image density | Mas |
| Diagnostic information content in digital radiology is generally___ than in conventional radiology if equivalent dose parameters are used. | higher |
| The_____ of the digital detectors and the capabilities of post processing allow us to obtain more information from the radiographic images then a film/screen system can. | wider dynamic range |
| Conventional films allows mistakes if a wrong radiographic technique is used: | images are too white or too black |
| Almost always, Digital technology provides user with a___since its dynamic range compensates for wrong settings even if the dose is higher than necessary | good image |
| Digital images can be numerically processed This is not possible in___ radiology!!. | conventional |
| ____ can be easily transmitted through networks and archived | Digital images |
| makes anatomic structures more visible and distinguishable | Contrast enhancement |
| results in smoothing of the structures | Contrast reduction |
| Another benefit to having a wider latitude or dynamic range as well as magnification | use windowing and leveling within this same image to see the various structures with different levels of density and contrast, Magnification of the entire image or specific structures |
| Factors that produce low contrast include | High KVP No grid or inadequate grid efficiency Inadequate beam limitation (i.e., collimation) Increased part size or tissue thickness |
| with film/sceen,___ selection should be based on desired subject contrast and grid selection | KVP |
| when it comes to using CR plates: they have a___ (more than a film/screen cassette). | wide dynamic range |
| CR plates are especially sensitive to | fogging, from both scatter and background radiation |
| The increased latitude allows for correction of exposure errors,but as the.. | exposure error increases, image quality will decrease! |
| Basic principles regarding the production of poor____ when using film/screen do not change with the use of digital | low-contrast images |
| Digital can maintain a useful density over a____ then that allowable with film/screen. | wider latitude |
| Failure to use a high enough___ setting produces quantum mottle | MAS |
| quantum mottle is | grainy, reticulated image for which digital post processing cannot compensate |
| Adequate___ is required to activate any digital image receptor! | MAS |
| a minimum CR ___ or ___ is required by many radiologists to ensure they are diagnosing from an image that meets the minimum data requirements of the CR system. | sensitivity number,index number |
| Underexposures in digital results in a “too noisy” image or | quantum mottle |
| Overexposures in digital___ be detected unless patient dose measurements are performed | cannot |
| Over exposure in digital yields good images with unnecessary but | high dose to the patient. |
| Over range of digitizer (extreme over exposure) may result in___ with potential loss of information | uniformly black area |
| A lack of sufficient incoming data to process an image: | Quantum Mottle,also known as quantum noise. |
| How is Digital Radiography different from traditional film/screen systems? | Digital Radiography utilizes a reusable detector |
| Digital Radiography can be divided into two groups: | Computed Radiography (CR) Cassette-based (indirect digital) Direct Digital Radiography (DR) Cassette-less (direct digital) |
| what has a rigid sheet with several layers that are designed to record and enhance transmission of the image from a beam of ionizing radiation | Photostimulable Phosphor Imaging Plates |
| The layers of a plate (PSP or IP) include: | a protective layer, a phosphor layer,a support layer, a conductor layer- a light shield layer and backing layer- |
| insulates from “handling trauma” | protective layer |
| active component” photostimulable phosphor | phosphor layer |
| the base on which to coat the other layers | support layer |
| grounds the plate to eliminate electrostatic problems and absorb light to increase sharpness | conductor layer |
| prevents light from erasing data on the imaging plate or leaking through the backing | light shield layer and backing layer |
| In order for CR to function, the imaging material must have the ability to__ and__the image information in a usable form. | store,release |
| The imaging plate phosphor will absorb more___ than the rare-earth phosphor and film, | low-energy scatter |
| The imaging plate is more sensitive to scatter both__ and___it is sensitized through exposure to the x-ray beam. | before and after |
| what begins with an x-ray exposure to the imaging plate. | Image acquisition |
| Radiation exposure causes__ of the imaging plate but some of the___of the beam is also stored within the plate. | fluorescence,energy |
| The latent image is stored within the____, similar to a latent image on film, but with wider___ | imaging plate,latitude. |
| The incident x-ray beam produces a___ within the photostimulable fluorohalide (phosphors) | latent image, |
| CR utilizes the principle of | photostimulable phosphor luminescence |
| The imaging plate is scanned by a___ laser beam | helium-neon |
| These laser beam scan causes the phosphors to emit the stored latent image in the form of | light photons, |
| These light photons are detected by the photosensitive receptors and then converted to an | electrical signal. |
| This electrical signal is, in turn, converted to a unique digital value for that particular level of | luminescence |
| Reading the imaging plate involves a finely focused____ that frees the trapped ___, | laser beam,electrons |
| After reading the imaging plate the electrons to return to a | lower energy state |
| Electrons moving to a lower energy state release blue-purple____ in proportion to the absorbed radiation | light photons |
| light photons or visible light is converted into an ____ which is in an analog form. | electronic signal |
| analog signal must be converted into a____ before the computer can work with the image information. | digital signal |
| The finely focused laser beam that scans each line of the imaging plate correlates to one line___ or___ dimension. | spacing,pixel |
| It is recommended that CR plates be erased____, if not used, to eliminate unwanted noise. | daily |
| the degree of geometric sharpness or accuracy of recorded detail of the structure | SPATIAL RESOLUTION |
| The smaller the pixel, the___ the spatial resolution. | higher |
| optimal processing from an CR imaging plate The__and __ should be centered within each pattern, and collimation should be parallel and equidistant from the edges of the imaging plate. | beam,part |
| a graphical representation or diagram that is generated by dividing a scanned area into pixels and determining the signal intensity for each pixel. | histogram |
| The shape of a histogram will correspond to the specific__and__ used for an exam. | anatomy,technique |
| Kilovoltage for computed radiography will control____ similar to film radiography | contrast |
| The Fuji computed radiography (CR) system uses an S number to assist in evaluating exposure and are | INVERSELY PROPORTIONAL |
| Kodak’s CR indicator system is called the Exposure Index and It is directly proportional. | directly proportional |
| Most CR systems do not send all the data acquired by the image receptor to the post-acquisition system because some data represents exposure below the diagnostic imaging range, while other data represents exposure far above the diagnostic range | Data Clipping |
| post-processed by algorithms that eliminate the overexposed portion of the image receptor output | Grossly overexposed images |
| a compound that absorbs x-rays and converts the energy to visible light by fluorescence | scintillator |
| A good scintillator yields many light photons for each incoming x-ray photon; __ to __ visible photons out per 1kV of incoming x-ray energy are typical. | 20,50 |
| Scintillators usually consist of a___ number material, which has high x-ray absorption. | high-atomic |
| Scintillators may be___ like phosphors or crystalline like cesium iodide. | granular |
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Lisadw