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test 2 review
| Question | Answer |
|---|---|
| a computer consists of? | input, output and processing devices |
| examples of output devices | Monitor, printer, and speakers |
| examples of input devices | Keyboards, Mice, Microphones, Bar code readers, Touch screens, Image scanners |
| What is machine language of 1s and 0s? | Binary Code |
| what is the single unit of data (1 or 0)? | Bit |
| what is made up of 8 bits? | Byte |
| what is the motherboard? | Largest circuitry board, contains many important small components for computer functionality |
| what is the CPU? | Microprocessor, brains of the computer |
| what part of the computer reads data from storage, manipulates data, and moves data back to storage or sends to an external device | CPU |
| what part of the computer contains simple set of instructions for computer | BIOS |
| what part of the computer runs start-up diagnostics, oversees basic functions of receiving and interpreting signals, and acts as intermediary between operating system and hardware | BIOS |
| What quantifies how much the actual EI varies from target exposure index? | DI (deviation index) |
| What is the reference exposure obtained when an image is optimally exposed | EI(t) (target exposure index) |
| what is the result of technologists not adjusting exposure factors as frequently required in screen-film imaging due to the wide dynamic range of digital imaging? | Dose creep |
| true or false? dose creep results in an increase of patient dose | TRUE due do the intention of correcting the resultant images with post-processing capabilities & letting the system "fix" the image with rescaling |
| what is used to remove region of brightness that surrounds radiation-exposed field that provides no useful information? | Electronic Cropping, Masking, Shuttering |
| post processing tool: brightness (level) | direct relationship b/t window level and brightness; adjusts brightness |
| post processing tool: contrast (width) | inverse relationship b/t window width and contrast; adjusts contrast |
| true or false? Narrow window width increases contrast | TRUE |
| true or false? Wide window width increases contrast | FALSE; remember it is an inverse relationship.. so wide window width DECREASES contrast |
| what computer software operations is available to radiographer/radiologist that allow manual manipulation of displayed image | Post-processing |
| what do look up tables (LUTS) do?? | following histogram analysis, LUTs provide method of altering image to change display of digital image |
| What determines range of histogram data set that should be included in displayed image? | Value of interest |
| What is a histogram analysis? | the computer analyzes histogram using processing algorithms and compares it to pre-established histogram specific to anatomical part being imaged |
| what is a graphic representation of data set of an image? | Histogram |
| what equalizes response of each pixel to uniform x-ray beam? | Flat fielding |
| what fixes inconsistent brightness (density) caused by anode heel effect? | Flat fielding |
| what stores information being currently processed within CPU on temporary basis? | Memory |
| what connects on the PC that link peripherals? | Ports |
| what delivers all electricity to PC? | Power Supply |
| what contains a fan to help keep the inside of the computer cool? | Power Supply |
| what is the main storage for programs and documents? | Hard Drive |
| what is the CD/DVD Drive? | information may be burned onto disks, capacity depends on type of CD or DVD |
| what element is how the x-ray is captured? | Capture Element |
| what is the coupling element? | How x-ray-generated signal is transferred to collection element |
| what element may be: photodiode, charge-coupled device, or thin-film transistor | Collection Element |
| what requires an imaging plate and separate processing system | Computed Radiography |
| TRUE OR FALSE. Barium fluorohalide PSP pertains to DR | FALSE; apart of CR |
| what is the process by which x-rays are converted directly into an electrical signal? | Direct DR |
| TRUE OR FALSE; Amorphous selenium (a-Se) pertains to DR | TRUE |
| What was developed by CT vendors to facilitate patient positioning imaging volume? | Scanned Projection Radiography -Scanning motion required several seconds leading to motion blur -Not widely used as a diagnostic imaging method |
| what process is this? x-rays are converted first to light then an electrical signal | Indirect DR |
| CCD imaging characteristics include: | High sensitivity – ability to detect and respond to very low levels of visible light Wide dynamic range – ability to respond to wide range of light intensities Size – very small |
| Indirect DR consists of ? | Cesium Iodide/CCD or CMOS Cesium Iodide/a-Si (TFT) Gadolinium Oxysulfide/a-Si (TFT) |
| What does CMOS stand for? | Complementary Metal Oxide Semiconductor |
| What is CMOS? | a special type of memory chip that retains information about personal computer’s hardware while computer is turned off |
| What uses a scintillator that converts x-rays into light and stores them into capacitors, amplifier pixel converts light photons into electrical charges | CMOS |
| What does ADC stand for? | Analog-to-digital converter |
| What does ADC do? | converts analog data to digital data to produce digital image via sampling and quantization |
| what determines how often analog signal is reproduced in its discrete digitized form? | Sampling Frequency ↑sampling frequency = ↑pixel density = ↑spatial resolution (pixel density - # of pixels per unit area) |
| what is preprocessing ? | it is largely automatic. the purpose is to improve image contrast and produce artifact-free digital image |
| what provides electronic calibration to reduce pixel-to-pixel, row-to-row and column-to-column response differences | Preprocessing |
| PROBLEM= term: Defective Pixel | description: Dead or unresponsive pixel |
| PROBLEM= term: Image Lag | description: Electronic latent image that remains |
| PROBLEM= term : Line noise | description: Voltage variations seen along each pixel that causes linear artifacts |
| SOLUTION FOR DEFECTIVE PIXEL= term: Interpolate adjacent pixel signals | description: Response of pixels surrounding defective pixel is averaged and value is assigned |
| SOLUTION FOR IMAGE LAG= term: Offset Correction | description: Application of an offset voltage before the next image is acquired |
| SOLUTION FOR LINE NOISE= term: Correct from dark reference zone | description :Application of voltage correction from a row or column of pixels in a dark |
Created by:
kbr2345
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