Image production Flashcards
What absorbs X-rays better?
Bone and cartilage high atomic number and density
If there is no x-ray absorption what colour shows up?
Black
Why do bones block X-rays?
High density
low opacity (white)
No silver depositied so light shines through
What hounsfield numbers are good attenuators?
bone metal 1000
What is the window width
Range of white to black shades
What is the centre of the window width?
Window Level
What is contrast used for?
To distinguish vessels
What is the order of IV contrast
Arterial phase quickly
Venous phase 60-70 seconds later
What is oral contrast helpful with?
Digestive structures
What happens if the slice thickness is too large?
Blurring
Order of density
Air Fat Soft tissue Bone Metal
Advantages of digital Imaging?
Image manipulation
Image transmission
Image storage
Image analysis and reconstruction
What is brightness defined as?
Intensity of light controlled by software algorithms
What is Image quality in DR?
Brightness Contrast Resolution Distortion Exposure Index Noise
What is contrast?
Difference in brightness between light and dark structures
What is resolution?
Sharpness of image
What is distortion?
misrepresentation of size due to source image distance and object image distance
What is the exposure Index?
Numerical representation of exposure the IR has received
What workstation is better?
Radiologist
What is noise?
Random disturbance that obscures clarity
What is post processing?
Enhancing images by changing pixel values
If the SNR is low can you post process?
No more signal cannot be made
What are some post processing options?
Windowing Smoothing Magnfication Edge enhancement Subtraction Image reversal Annotation
What does window width and level control?
Contrast
and brightness
