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EO Chapter 15-18
Equipment operations chapters 15-18
| Question | Answer |
|---|---|
| T/F. Computed radiography is a form of digital radiography. | True |
| CR signal loss is objectionable after approximately hours? | 8 |
| The diameter of the laser beam determines the _____ of the CR imaging system. | spatial resolution |
| Small laser beam diameter is critical for ensuring high _____. | spatial resolution |
| Sampling and quantization are two processes of ______. | ADC |
| CR is based off the phenomenon of _____. | PSL |
| In DR, the latent image is actually sitting where? | On your detector |
| The ability to render small objects on the image is known as: | spatial resolution |
| Relates to the number of line pairs in a given length. (lp/mm) | Spatial frequency |
| An imaging system with ____ spatial frequency has ___ spatial resolution. | higher, better |
| Spatial resolution in digital imaging is based on _____. | pixel size |
| The number of gray shades that an imaging system can produce is known as: | dynamic range |
| Image noise limits _______. | contrast resolution |
| Window width controls | image contrast |
| Window level controls | brightness |
| ____ is a measure of x-ray absorption efficiency. | DQE |
| The scatter x-ray beam has a _____ energy than the primary x-ray beam. | lower |
| The basic photometric unit is the ____. | lumen |
| Operator manipulation of digital images occurs in ____. | Postprocessing |
| What are the 4 principle characteristics of any image? | Spatial resolution, contrast resolution, noise, artifacts |
| The ability to distinguish between differences in intensity in an image. | Contrast resolution |
| Computer defects such as electronic noise, inadequate sampling and inadequate quantization refers to: | noise |
| The activator of the photostimulable phosphor is | europium |
| Four steps of creating an image with CR is: | metastable state, stimulate, read, and erase |
| Stimulation of the latent image results from the interaction of an: | infrared laser beam |
| Measures the ability of an imaging system to convert alternating signals in the x-ray beam into pixel values is known as: | MTF |
| Measures light intensity | lux |
| Measures the total amount of light output | lumen |
| Electric power is measured in | Watts |
| The measurement of the power that is producing brightness | watts |
| Science of the response of the human eye to visible light is known as: | photometry |
| What are some examples of a Hard copy. | Film and viewbox |
| List some examples of Soft copy | LED and LCD display, and a digital cathode ray tube |
| An image display monitor that uses a stream of electrons to stimulate phosphors | Digital cathode Ray tube (CRT) |
| What is the purpose of magnification in post processing? | To improve visualization and spatial resolution. |
| What are the 4 principal components of PACS? | Imaging acquisition system, display system, network, and storage system. |
| Collection of X-rays transmitted through the patient. | data acquisition |
| Detector that allows direct conversion of X-rays to electrical signals through the use of amorphous selenium as the photoconductor. | Flat panel a-Se detector |
| Detector that uses amorphous silicon as a photodiode during the process of indirect conversion of X-rays to electrical signal | Flat panel a-Si detector |
| Array for readout of electrical charges generated by the photodiode flat-panel layer in an indirect flat-panel digital detector | Thin film transistor (TFT) |
| Standard that essentially addresses the communication of images (image data). | DICOM |
| Indirect detectors use a ____. | phosphor |
| Direct detectors use a _____. | photoconductor |
| Fill factor affects ____ and _____. | spatial resolution and contrast resolution |
| A perfect digital detector would have a DQE of ___. | 1 |
| PSP imaging plates are erased by flooding the plate with: | light |
| The digital detector used in CR imaging is the ___. | imaging plate (IP) |
| The layer of the imaging plate that traps electrons during exposure is the ____ layer. | active |
| Laser scanning produces a luminescence (light) that is proportional to the stored ____. | latent image |
| The amount of detail present in any image is known as ____ resolution. | spatial |
| The number of trapped electrons is proportional to the ____. | absorbed radiation in the receptor. |
| Photostimulable phosphors have the property of creating and storing a/an ___ when exposed to the x-rays. | latent image |
| The phosphor layer is made of phosphors from the _____ family | barium flurohalide |
| Exposure latitude is conventional radiography as ____ is to DR. | dynamic range |
| Noise on a digital image is the summation of inherent electron system noise and quantum mottle noise. Of these two, the radiographer can improve the noise on an image by: | increasing exposure technigque |
| When matrix size is increased and pixel size goes down. | spatial resolution increases |
| If the digital FOV is 1024 and the display matrix is 256, the pixel size would be: | 4 pixel size = 1024 / 256 |
| Each binary number is called a: | bit |
| Computerized digital images consists of a ____ of picture elements, each with video display value or gray shade. | matrix |
| An MTF of ___ represents a perfect transfer of spatial and contrast resolution. | 1 |
| _____ produces lateral spreading of light, which destroys the spatial resolution on the image. | Powdered phosphors |
| Which of the following reduces the output image from the scintillator phosphor to the size of the CCD array? | optical system |
| The best S:N ratio is: | 1000:1 |
| Which layer used in indirect flat-panel digital detector is usually cesium iodide or gadolinium sulfate? | x-ray scintillator |
| In all systems, exposure outside the range indicates: | both overexposure and underexposure |
| Which of the following will detect the light from the CsI scintillator in the indirect flat-panel TFT detector? | sensing area |
| _____ is the maximum range of pixel value a computer, display monitor, or other digital device can store. | bit depth |
| A wider window width: | Decreases contrast and increases grays |
| The layers of a flat-panel indirect capture detector include the following: | Scintillator phosphor, photodiode, TFT array |
| Which term refers to the time it takes for the latent image to disappear? | fading |
| The percentage of a detector elements area dedicated to photon absorption? | fill factor |
| When the quality of a digital detector is inspected for purchase, the preferred detector for purchase would have a | DQE of 68% and MTF of .80 |
| Digital images are less sensitive to scattered and background radiation. T/F | false |
| A digital image is composed of a series of rows and columns known as a ____. | matrix |
| Given the negative feedback due to underexposures, what does a predictable and unfortunate use of higher exposures result in? | dose creep |
| Refers to projection radiography, whereby computers process data collected from patients using special electronic detectors that have replaced the X-ray film cassette. | digital radiography |
| With indirect flat-panel TFT detectors, what is used to first convert X-ray photons into light photons? | scintillator layer |
Created by:
Kdobson