Analog/Digital Flashcards
Describe Long Scale Contrast.
Low contrast Small differences Shades of gray Abdomens/chest Higher kVp
Describe secondary factors for contrast.
Air gap- ^ OID, ^ contrast. Used for lateral c spines.
Body habitus- ^, decreases contrast.
Beam restriction- ^, ^ contrast, reduces scatter.
Grids- ^, ^ contrast, reduces scatter.
Brightness?
Measurement of the luminance of a monitor calibrated in units of candela per square meter.
Grayscale?
Grayscale is the difference of the densities on the digital image.
Grayscale is manipulated by?
Window width.
Brightness is manipulated by?
Window level.
Contrast resolution.
The smallest exposure change or signal difference that can be detected in the IR.
Contrast resolution is controlled by?
Dynamic range and bit depth (quantization)
Dynamic range?
Range of exposures that may be captured by a detector.
Bit depth (quantization)
The # of bits per pixel.
Pixel size =?
Matrix.
2 parts to spatial resolution?
Receptor (extraction) Display Monitor (display)
Exposure latitude?
Range of exposures which produce quality images.
Image noise?
The deterioration of a radiographic image by unwanted interference in x ray signal detection.
Describe the types of image noise.
Electronic noise- intrinsic within the system.
Quantum noise- insufficient signal strength
Scatter/fog- also increases noise.
Best way to decrease scatter?
Collimation.
Major controlling factor for recorded detail.
FSS.
Secondary factors for recorded detail.
Body habitus- decreases detail. Higher OID increased magnification.
Motion- decreases detail.
OID- decreases detail, increases magnification
SID- increases detail, decreases magnification.
Film screen combination- decreases detail, increases phosphors size.
Size distortion?
Magnification caused by excessive OID, or insufficient SID.
Major controlling factor for distortion?
Patient positioning.
Artifacts?
Distortion or error in a image.
Describe artifacts secondary factors.
Image receptors- cassette based, cassette less.
Processing- cassette based
Software- in computer for digital imaging
Exposure- jewelry, clothing.
Image blur?
Unfocused image.
Describe secondary factors for image blur.
Receptor- cause within any receptor
Geometric- FSS, SID, OID
Motion- motion of patient, part, tube, IR.
