Fluoroscopy Flashcards
What is Fluoroscopy?
Real time imaging viewed on a display monitor in the clinical room
What is the matrix size and grey scale for Fluoroscopy?
512 x 512 pixels and 8 bits of grey scale
What types of images can Fluoroscopy acquire?
Continuous (cine) or pulsed fluorographic images
What is Fluorography?
Images usually formed and viewed after the x-ray exposure is complete
What are the advantages of Fluorography over Fluoroscopy?
Better quality images but at higher doses
What is the matrix size and grey scale for Fluorography?
1024 x 1024 pixels with each pixel representing 10 bits of grey scale information
What are ‘Greyscale’ digital x-ray imaging modes?
Fluoroscopy, digital cardiac, and digital spot imaging
What is Subtractive digital imaging?
Base image taken which is then subtracted from the image with contrast to result in an image showing the contrast only
What is an Image intensifier (II)?
A system that converts the input light into a much higher output (gain or intensification)
What is the formula for brightness gain (Gbrightness)?
Gbrightness = Gminification x Gflux
What does Gminification describe?
The increase in brightness due to the demagnification of the image in the II tube
What is the formula for Gminification?
Gminification = (Dinput / Doutput)^2
What is the Image intensifier conversion factor (Gx)?
Gx = L / X’ where L = luminance of the II output and X’ = II entrance dose rate
What factors affect the brightness gain of an II tube?
Magnification and Flux
What are the standard configurations of radiography/fluoroscopy equipment?
Under table x-ray tube with an over-couch II system, Table can be tilted and rotated, Radiologist stands beside patient
What are the configurations of Remote control R/F equipment?
X-ray tube mounted over the bed and II system underneath, Higher scattered dose so radiologist stands behind screen
What is a Fixed C-arm?
II x-ray tube and II system attached to a C-structure that allows rotation and movement
What is a Mobile C-arm?
System that can be transported on wheels to different locations
What is the II input window?
Convex metal shield, usually aluminium or titanium foil, that covers the input face of the II
What is the Input phosphor made of?
Layer of sodium activated caesium iodide (CsI:Na)
What is the thickness of CsI:Na in the Input phosphor?
400-500μm
What does the Photocathode do?
Absorbs fluorescent light photons and releases a pattern of electrons
How many electrons are released per absorbed x-ray photon in the Photocathode?
Approximately 200 electrons