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Digital Imaging 1
Module 1
| Question | Answer |
|---|---|
| Which X-ray beam contains the useful or diagnostic information that is transferred to the image receptor? | Remnant Beam |
| What is a major advantage of digital imaging over analog? | Large dynamic range |
| Advantages of digital imaging: 1) 2) 3) 4) | 1)Allows us to see structures that would have previously required additional imaging; 2)Radiologists can manipulate the image to see structures differently; 3)Making multiple copies is simple; 4)Can be electronically distributed |
| In an analog image receptor, the intensifying screen converts the __________ _______ _______ exiting the patient into __________. | Remnant x-ray beam; Light |
| With an analog IR, the _______ is the recording device and uses the x-rays reaching the _________ and __________ produced by the intensifying screen to create the image. | Film; Film; Light |
| With an analog IR, the image created on the film directly after exposure is the ______________ image. The film must be ______________ to create the ___________ image. | Latent; Processed; Manifest |
| During Analog to Digital Conversion (ADC) the process of assigning numeric values to the analog output signal of the photo detector is termed ________________. | Quantization |
| The quantization of the analog signal to numeric values determines the __________ levels of the image. | Gray |
| Binary language consists of a system of ______ symbols, either a _____ or _____ to manage data. | Two; 0; 1 |
| Each number in binary language is called a _______, short for __________ _________. | Bit; Binary Digit |
| A _______ is a string of _____ bits, also referred to as a ________. | Byte; 8 Bits; "Word" |
| The number of gray levels that can be digitized depends on ______ ________. | Bit Depth |
| If 6 bits are available for the bit depth, there will be ______ shades of gray that can be represented. 8 bits would mean that there could be _______ shades of gray that can be represented. | 64; 256 |
| 256 Shades of gray would be representative of a bit depth of _____ bits. | 8 bits |
| Pixel size is measured from _______ to ______ of an individual pixel; Pixel Pitch is measured from the _________ of one pixel to the __________ of an _____________ ________. | Side to side; Center; Center of an adjacent pixel |
| The size of each pixel within a matrix determines ___________ ___________. | Recorded Detail |
| As the size of the pixel decreases the ____________ ___________ will ____________. | Recorded Detail will Increase |
| As the size of the pixel increases the ____________ ____________ will __________. | Recorded detail will decrease |
| The typical matrix size for radiography may be _________ x _______ with a bit depth of _______. A CT scan would have a matrix size of ______x_______ with a bit depth of _____. | 3000 x 3000; 12; 512 x 512; 16 |
| Name the 4 types of digital image receptors: | 1)Photostimulable Phosphor (PSP); 2)Flat panel with a thin-film transistor (TFT); 3) Charge-Coupled Device (CCD); 4)Complementary Metal Oxide Semiconductor (CMOS) |
| Flat-Panel detectors with thin-film transistors can either be __________-based or _______________-based. | Scintillator; Nonscintillator |
| ____________: The ability of certain materials to respond to excitation and give off light. | Scintillation |
| The 3 characteristics of Image Detectors used to assess the performance of the receptors: | 1)Absorption Efficiency 2)Conversion Efficiency 3)Detective Quantum Efficiency |
| __________ __________ is the measure of a percentage of energy that strikes a receptor material that is actually absorbed by the receptor. | Absorption Efficiency |
| __________ __________ is the percentage of energy absorbed by a receptor that is converted to usable output. | Conversion Efficiency |
| This is the product of the amount of energy absorbed and the amount of energy converted to useful output. | Detective Quantum Efficiency |
| PSP Image Plates are scanned by a _________ _________ ___________ to extract the image data by causing electrons at high energy states to release their energy as a _________ ___________. | Red Laser Light; Blue light |
| What happens to the electrons in a PSP image plate after it is scanned and releases the energy from the X-ray beam? | The electron returns to it's lower energy resting state. |
| Thin Film Transistors in a _________-________ plate collects ___________ emitted from ___________ ___________ or ___________ ___________. | Flat-Panel; Electrons; Amorphous Selenium or Amorphous Silicon |
| The Thin-Film Transistor in a flat-panel image plate collects the released electrons in an area of the circuit assembly called ___________ ___________ or _______. | Detector Elements or DELs |
| The x-ray beam contains photons of varying energies and pass through varying densities of body tissue to the image receptor. What are these nonuniform, nonuseful variations that are captured that do not add to the useful information? | Noise |
| The measure of the useful information captured to the nonuseful, random variations captured is referred to as the _________ to ___________ ratio. | Signal-to-Noise Ratio |
| An advantage of CCD Receptors is that they respond to _________ _______ _________ from a scintillator than other types of receptors. | Lower Light Levels |
| CCD's are suitable for _____-________ imaging and also produce images ___________ and will ____________ ___________ for the next image. | Low-Dose imaging; Quickly; Instantly Refresh |
| CCD's are excellent image receptors for _________________ imaging. | Fluoroscopic |
| __________ is a measure of an image receptor's ability to create an output signal that accurately represents the input signal of the x-ray beam exiting the patient. | DQE |
| A higher DQE indicates that a receptor is _________ efficient in converting the input x-ray signal and this means that a __________ exposure is required to create an optimal image. | More Efficient; Lower |
| The ability to distinguish small objects adjacent to each other is __________ _________ and is measured in a unit called ______________. | Spatial Resolution; Line Pairs per mm |
| Spatial Resolution is measured in ______ _______ _____ ___________. | Line Pairs Per millimeter |
| Changing the sampling frequency of a ________ plate reader affects __________ size and thus ___________ ___________. | PSP; Pixel; Spatial Resolution |
| Lower sampling frequencies for a PSP plate reader means that __________ samples are taken and a __________ pixel size which will result in ___________ spatial resolution. | Fewer; Larger; Decreased |
| Sampling frequencies for PSP readers can range from _______ pixels per mm to _______ pixels per mm. The _______ pixels per mm provides better spatial resolution. | 5; 20; More |
| With Flat Panel Detectors (FPD) ___________ are collected in the ______s of the _______-________ _________. | Electrons; DELs; Thin-Film Transistors |
| Thinking of the DELs in a Flat Panel Detector as a pixel: A DEL size that collects 50 microns compared to a DEL size that collects 200 microns will provide what kind of spatial resolution? | 50 micron DELs provide better spatial resolution than a 200 micron DEL. |
| 1) 200 micron DELs will provide what kind of spatial resolution? (2) 100 micron DELs? (3) 50 micron DELs? | (1) 2.5 Line pairs/mm (2) 5 Line pairs/mm (3) 10 Line pairs/mm |
| The Nyquist Theorem states that for a desired spatial resolution with PSP sampling frequency that ________ the number of pixels must be sampled to display the desired line pairs per mm. | Twice |
| Nyquist Frequency: 1) To display 2.5 line pair per mm = ________ pixels per mm must be sampled. (2) 20 pixels sampled per mm will give a spatial resolution of _______ line pairs per mm. | 5; 10 |
| Digital Receptors can produce an image that appears acceptable on a display monitor from _______ % underexposure through to _______% overexposure. | 50% Underexposure to 100% Overexposure |
| To determine incorrect exposure values on a digital image, a technologist should be able to determine underexposure of less than 50% of the desired mAs because the image will look _________ or ___________. | Mottled or Noisy |
| When an image is overexposed by 100% to 200% of the desired value the image will have a loss of __________ and all parts will appear uniformly ____________. | Contrast; Penetrated (saturated) |
| Receptor blur originates in the ___________. | Equipment |
| What are the 3 sources of image blur? | Receptor, Geometric, Motion |
| The 3 geometric factors affecting geometric blur: | FSS, SID, OID |
| During fluoroscopy, in order to magnify an image the __________ phosphor is __________ and the ___________ phosphor is ___________. | Input phosphor is decreased / Output phosphor remains the same. |
| These IR's use TFTs: | Flat Panel Detectors (FPD) |
| These Flat Panel Detectors are "Direct Image Capture" devices which means what? | Amorphous Selenium (Nonscintillation) based meaning photons are converted directly to electrons |
| The Flat Panel Detector that requires an extra step to convert light to electrons are what type of scintillation and uses amorphous ___________. | Scintillation & uses Amorphous Silicon |
| Amorphous Selenium and Amorphous Silicon both release electrons to be collected in the Thin Film Transistors. What is the scintillation material used for indirect capture and what is the photoconductive material used to convert light into electrons? | Cesium Iodide or Gadolinium Oxysulfide: Converts X-ray photons to light; Amorphous Silicon converts light to electrons |
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foster1317
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