Term
| What are the 3 main advantages of DF over CF? |
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Definition
| 1. faster image acquisition 2. post-processing of images is possible to enhance image contrast 3. dose reduction for patients, physicians, and staff |
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Term
| Unlike conventional fluoro, w/ DF, the under table x-ray tube actually operates in __________ mode. |
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Definition
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Term
| Tube current is measured in ___s of mA, instead of less than 5 mA as with CF. |
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Definition
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Term
| In DF, the tube current can be measured in 100s of mA because the x-ray beam is pulsed in a manner called: |
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Definition
| pulsed-progressive fluoroscopy |
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Term
| Image rates of _-__ images per second are possible w/ modern DF systems using pulse-progressive fluoro. |
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Definition
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Term
| In DF, the x-ray _________ must be capable of switching on and off very rapidly |
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Definition
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Term
| The time required for the x-ray tube to be switched on and reach selected levels of kVp and mA is called the ____________ time. |
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Definition
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Term
| The time required for the x-ray tube to be switched off is the _________ time. |
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Definition
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Term
| DF systems w/ interrogation and extinction times of 1 ms or less must use three-phase or ____-_______ generators. |
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Definition
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Term
| The ___ of DF is used in place of the television camera tube of CF. |
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Definition
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Term
| The spatial resolution of a CCD is determined by its: |
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Definition
- physical size
- pixel count |
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Term
| CCD systems using a 1024 matrix can produce image w/ a resolution of __ lp/mm. |
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Definition
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Term
| The CCD has a higher sensitivity to ____ and lower electronic noise than a television camera. |
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Definition
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Term
| What are the advantages of CCDs and basically all DF over CF? |
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Definition
- high spatial resolution
- high SNR
- high DQE
- no warm-up required
- no lag or blooming
- no spatial distortion
- no maintenance
- unlimited life
- unaffected by magnetic fields
- linear response
- lower dose |
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Term
| The linear response of DF is particularly useful for image subtraction. The result is improved ______ range and better _______ resolution. |
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Definition
- improved dynamic range
- better contrast resolution |
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Term
| Perhaps the single most important feature of CCD imaging is its _____ response. |
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Definition
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Term
| The ____ _____ system is smaller, lighter, and more easily manipulated than an image intensifier system. |
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Definition
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Term
| The _____ _______ is limited by non-uniform spatial and contrast resolution from the center to the periphery of the circular image. Also the image deteriorates w/ age. |
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Definition
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Term
| With ____ _____ technology, the image is uniform over the entire receptor and does not deteriorate w/ age. |
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Definition
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Term
| What are the advantages of the flat panel detector over image intensifiers? |
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Definition
| - distortion free images - constant image quality over the entire image - improved contrast resolution over the entire image - high DQE at all dose levels - Rectangular image area coupled to rectangular monitor - Unaffected by external magnetic fields |
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Term
| Video systems used with DF can range from ___ line systems to systems displaying over ____ lines. |
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Definition
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Term
| Conventional video systems have two limitations that restrict their use with DF: |
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Definition
| 1. The interlaced mode of reading the target of the TV camera can significantly degrade the digital image. 2. Conventional TV camera tubes are relatively noisy, displaying a SNR ratio of about 200:1, when a ratio of 1000:1 is necessary for DF. |
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Term
| Conventional TV cameras use the _________ method to read their target assemblies. |
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Definition
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Term
| In DF, the camera tube reads in _________ mode. In this mode, the electron beam of the TV camera tube sweeps the target assembly continuously from top to bottom in 33 ms. |
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Definition
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Term
| The _______ of the computer is important in determining image quality, the manner and speed of acquisition, and image processing and manipulation. |
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Definition
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Term
| What are 3 important characteristics of a DF system that is computer controlled? |
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Definition
1. image matrix size
2. system dynamic range
3. image acquisition rate |
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Term
| DF systems use an _____ __ _____ ______, situated between the CCD/TV Camera and the computer, to convert the continuously varying (analog) output signal from the CCD/TV Camera to a digital signal. |
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Definition
| Analog to Digital Converter (ADC) |
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Term
| To be compatible with the computer, the ADC must have the same ______ range as the DF system. |
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Definition
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Term
| *The dynamic range of each pixel, the number of pixels, and the method of storage determine the ____ with which the image can be acquired, processed, and transferred to an output device.* |
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Definition
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Term
| The _____ the image matrix, the longer it takes to acquire the image and the more storage space it takes. |
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Definition
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