CR and DR
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| __________ means having no definite shape. | Amorphous
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| Semi-conductor material which means allows some flow of electrons between atoms. | silicon
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| Direct conversion detectors to detect exit radiation and form latent image. | selenium
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| TFT | thin film transistors; electronic switch to allow charges to be collected at each pixel.
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| Automatic rescalling | software that adjusts gray scale values in histogram
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| Number of shades of gray | bit depth
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| How is bit depth calculated? | 2 to the n power; n= 8; 2 to the 8th power = 256 shades of gray
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| Bit depth is also known as ______ _______. | Contrast resolution
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| Dynamic range | range of exposures over which a detector can acquire image data
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| Detective Quantum Efficiency (DQE) | ability to detect or absorbe x rays (dose level required for optimal image)
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| Field of view or detector size | useful acquisition area of imaging device
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| Software must detect collimated edges for proper histogram analysis. | beam part alignment latitude
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| Histogram | identifies all densities on an IP; pattern varies for body part
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| Unwanted density | image noise
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| Spatial resolution | ability to image an object faithfully
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| Measure of the ability of the imaging system to preserve signal contrast as a function of the spatial resolution | modulation transfer function
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| Look Up Table (LUT) | results image with correct contrast and brightness; maps adjusted data through s curve
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| How is the LUT adjusted? | By changing window width or range after initial processing
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| Number of pixels in rows and columns | Matrix size
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| Highest spatial frequency that can be recoreded by a digital detector. | Nyquist Frequency
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| Pixel pitch | distance from the center of one pixel to the center of another pixel
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| Photodiode | electronic element that converts light into electronic charge; indirect
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| photoconductor | TFT detector that converts x ray directly into electrons without photodiode
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| Pixel | picture element
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| Processing algorithm | mathematical codes used by software to provide image
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| 3E picture element of tissue | voxel
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| _____ _____ determines resolution. | pixel size
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| What are the five things that affect spatial resolution? | time, SID, OID, FSS, IR
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| Fourier transformation | mathematical method to convert data
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| What is being described:indirect capture, cassette-based, film less | Computed Radiography
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| What are the five layers of the cassette based image plate? | backing, base, anti-halo/reflective, phosphor, protecftive
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| What is the purpose of the backing layer? | protects from handling artifacts; contains bar code info
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| The base is made of what material? | polyester
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| What is the purpose of the base? | To support the phosphor layer.
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| This layer prevents the IRD laser light from penetrating but allows reflected light to be emitted to strike phosphor to produce latent image | anti-halo/reflective layer
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| What is the PSP layer made of? | barium fluorohalide doped with europrium
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| Which layer captures the latent image? | phospor layer (photostimuable phosphor layer)
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| Image created after exposure but before developing. | latent image
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| What layer provides protection and a cleaning surface? | protective layer
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| What are the steps of the PSP IP luminance? | 1. Stored energy is released to photomultiplier tube and produces light;2. light converted to electrical energy;3.analog to digital conversion;4. digital signal sent to computer
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| Exposed film is ____ more exposable to light. | 8x
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| IRD | image reader device
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| What are some advantages to using an Image Plate for digital radiography? | indefinite life, hold image up to 48 hrs, cassette does not need to be light tight,
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| What is the most common compression ratio? | 1:1-1:3
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| What happens when the IP is placed within the IRD? | 1. pre-read: sets boundaries of collimation 2. main read: scanned by laser that causes phosphors to emit stored latent image in form of light photons
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| S value # | proper range of exposure ; 100-200
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| If the s value is over 200 the image is _______, and if the s value is under 100 the image is ________. | Underexposed, overexposed
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| Is the s value # and exposure direct or indirectly related? | indirect
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| Dose Area Product (DAP) | digital radiography systems proper range of exposure
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| Image noise is ________ related to contrast. | inversely
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| Is it beter to have a high or low signal to noise ratio? | high which will decrease noise
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| Window level controls _______ . Their relationship is _______. | density; direct
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| If you increase your window width, what will happen to your contrast? | decrease (indirectly related)
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| Smoothing | software function that reduces noise
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| Edge enhancement | artificial increase in contrast of displayed image at an edge
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| TFT | thin film trnsisistors - collects electronic signal as a matrix
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| DICOM standars | Digital Imaging and Communications in Medicine; system of standards that permits a wide range of digital imaging programs to talk to one another ex. Konica to communicate with GE
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| HL7 | health level 7; standard needed to allow HIS to communicate with RIS (Meditech to PACS)
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| PACS | Picture Archiving and Communication system; sotrage and transmission for digitized images
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| PACS can be manipulated by: | windowing, enlargement, tissue density readings, subtraction
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