Ways by which getting radiographic image
IMAGE ACQUISITION
RAW DATA ACQUISITION Involves THREE STEPS
- Positioning
- Exposure Field Alignment & Collimation
- Exposure Technique Selection
- a graphical display
of the pixel intensity distribution for a digital image. - A plots the number of pixels found at each pixel value
Histogram
3 steps a Radiologic Technologist must correctly ensure before exposing the patient to radiation
- Positioning
- Exposure Field Alignment
and Collimation - Exposure Technique Selection
refers to the range of X-ray intensity that the detector can image. To obtain high-quality digital radiographs, radiographic detectors that give good contrast over a wide dynamic range are required
Dynamic Range
is a type of radiographic
noise directly related to the number of x-ray photons exiting the patient and
forming the radiographic image
Quantum Mottle/ Quantum Noise
refers to unwanted signals that corrupt, mask, or interfere with the desired signal which is being processed by an electronic
circuit
Electronic Noise
- they contain quantum
mottle (noise), appear
under-penetrated and often are deemed to be undiagnostic - appear ‘grainy,’ and display poor penetration
Underexposure
will have a distinct lack of quantum mottle while appearing ‘saturated’ or in extreme cases ‘burnt out’ whereby anatomy is completely obliterated from the radiograph
Overexposure
Foreign materials on the light collection guide in a CR reader produces bright linear lines in the output image
Artifacts
a patient-based artifact that occurs with voluntary or involuntary patient movement during image acquisition
Motion Artifact
Visual inconsistencies or errors that occur at the boundaries where the
individual images are merged together
Stitching Artifacts
Latent image from previous
exposure present on current exposure
Detector image lag or ghosting
electronics are visible on the exposed image
Backscatter
Where a detector element fails to receive a proper signal and therefore appears as a bright white
dot in an x-ray image
Dead pixel artifact
- large areas of signal loss
- due to detector drop
Signal Dropout/ Speckled Radiopaque Spot
