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Image Acquisition
Question | Answer |
---|---|
recorded detail | clarity, resolution, with which anatomic structures are represented in the x-ray image (Radiology Prep, p.298). |
image quality | image density, contrast or gray scale, recorded detail, and distortion (Radiology Prep, p.298). |
geometric factors include: | detail/resolution and distortion, distance, patient factors, focal spot size (Radiology Prep, p.298-308). |
photographic factors include: | motion and intensifying screens (Radiology Prep, p.309-313). |
visibility factors include: | density and contrast (Radiology Prep, p.314-348). |
2 types of automatic exposure control (AEC) | phototimer and ionization chamber (Radiology Prep, p.349). |
fixed kV technique | chart specifies a particular kV for each body part or type of exam (Radiology Prep, p.352). |
variable kV technique | the mAs is fixed and the kV is increased as part thickness increases (Radiology Prep, p.351). |
digital images require: | large amount of digital storage space, high bandwidth in PACS, and high resolution display monitors (Radiology Prep, p.354). |
pixel | 2-D, picture element, measured in XY direction. pixel pitch is the distance between pixels (Radiology Prep, p.355). |
voxel | 3-D, has depth, volume element, measured in Z direction (Radiology Prep, p.355). |
matrix | number of pixels in XY direction (Radiology Prep, p.355). |
FOV | how much of the part/ patient is included in the matrix (Radiology Prep, p.355). |
pixel size affected by | change in matrix size, and change in FOV (Radiology Prep, p.356). |
CR spatial resolution improves with | smaller pixel pitch, greater pixel/mm, greater sampling frequency (Radiology Prep, p.356). |
functions of digital imaging systems | sensor function, display function, and storage function (Radiology Prep, p.356). |
PSP storage plate layers | protective coat, reflective backing, polyester base support material, antistatic layer, lead foil backing (Radiology Prep, p.359). |
CR resolution increases as | PSP phosphor size decreases, laser beam size decreases, monitor matrix size increases (Radiology Prep, p.363). |
CR features | traditional x-ray equipment, uses IPs and cassettes, display, image preview and post processing (Radiology Prep, p.363). |
DR features | needs new equipment, uses no IPs or cassettes, immediate image display, image preview and post processing, higher DQE or lower patient dose (Radiology Prep, p.363). |
types of artifacts | handling, processing, and exposure (Radiology Prep, p.383). |
information required on each x-ray image | patient name/ identification number, side marker, examination date, institution's name (Radiology Prep, p.384). |
optional information on each x-ray image | patients age or date of birth, attending physician, time of day, radiographer identification (Radiology Prep, p.384). |
film processing steps | developer, fixer, wash, and dryer (Radiology Prep, p.386). |
3 stages for PSP | x-ray exposure, scanning/ reading, and erasure (Radiology Prep, p.390). |
CR resolution increases as | PSP phosphor size decreases, laser beam size decreases, monitor matrix size increases (Radiology Prep, p.406). |
electronic imaging | brightness changes with window level, contrast changes with widow width, has wide dynamic range/ latitude, fading can occur with delayed processing, IPs are very sensitive to x-ray fog (Radiology Prep, p.407). |
exposure factors | mA, time, kV, and distance (Radiology Prep, p.298). |
factors that affect recorded detail/ resolution | OID, SID, focal spot size, patient factors, intensifying screens, and motion (Radiology Prep, p.298). |
distortion | size distortion (magnification), and shape distortion (elongation. foreshortening) (Radiology Prep, p.298). |
factors that affect distortion | size distortion is affected by OID and SID; shape distortion is affected by alignment of the x-ray tube, anatomic part, and IR (Radiology Prep, p.298). |