Digital Image Processing
T/F: the smaller the pixels, the greater the spatial resolution
True
Window leveling controls
Brightness
Common PSP Phosphors
Barium Fluorohalide Bromides (BaFBr:EU)
Barium Flourihalide Iodides (BaFl:EU)
Difference between direct and indirect conversion
Indirect conversion uses a scintilator
How do we reduce ESE to pt?
High KVP low mAs
T/F: The LUT is used to adjust the contrast of the image
True
Computers operate using what type of language
Binary machine
T/F: The tech should wait 1-2 hours after taking the image to process the cassette
False: The latent image will lose appox. 25% of its energy within 8 hours. Techs should process as soon as possible after exposure
Two types of scintillators
Cesium Iodide
Gadolinium oxysulfide
What is detector saturation
extreme case of overexposure
Converts X ray photons to light
What determines the range of pixel bit depth?
The ADC
What captures the light when reading CR plates
Photomultiplier Tubes (PM tubes)
T/F: CMOS is preferred over CCD
False, not as stable and susceptible to noise
Fixed KVP, variable mAs
Variable KVP, fixed mAs
Fixed KVP, Variable mAs is more suited for DR
The ADC involves what two steps
Sampling & Quantification
A measure of sensitivity and accuracy by which the IR converts the incoming data to the output viewing device
DQE
Explain what happens after the PM tubes collect the light
The PM tubes convert the light to an electric signal which is sent to the ADC. The ADC sends the digital data to a computer for further processing. IP is erased via exposure to intense light
T/F: A higher fill factor indicates lower spatial resolution and contrast
False: A higher fill factor increases x-ray does efficiency and yields higher spatial resolution and contrast
DI values of __ or greater are considered an ALARA violation and are cause for concern
+3
We use this algorithm to get from spatial location to frequency
Fourier Transformation
Explain the steps in latent image production
The x ray photon comes in and interacts with the phosphor, which creates a photoelectric interaction. This reaction excites the low energy photo electrons, which creates a hole in the crystal phosphor. (F traps). The latent image is then created
What is the pattern called in with CR data is collected
Raster pattern
Name 3 DR panel precautions
do not trop detector, place plastic bag over protector to protect from fluid, do not have pt. stand on detector
T/F: We want low SNR ratio
False- High SNR=low noise