week 8 Flashcards
(36 cards)
factors affecting fluoroscopic image quality
- contrast
- noise
- sharpness
- distortion
- temporal resolution
how can image contrast be improved
- use of exogenous contrast agents
- radio-opaque makers on instruments
- high exposure rates
how can noise be improved
using higher frame rate
what is sharpness influenced by in II
- display matrix
- focal spot size
- image noise
- motion
- FOV (or geometric magnification)
what is sharpness in FPD dependent on
- display matrix
- focal spot size
- image noise
- motion
- pixel size of receptor
types of image distortion/ artifacts in a cathode ray tube (CRT) TV monitor (Vidicon/Plumbicon)
- veiling glare
- vignetting
- blooming
- pincushion distortion
- S distortion
daily QC by the radiographers
- visual check
- functional checks - fluoroscopic unit and other accessories equipment
weekly routine QC check by radiographers
- top up consumables
- cleanliness of the storage compartment
- storage devices load
- removal of stored data to clear the worklist on equipment
2 non vascular interventional radiology procedures
- biopsy
- FNAC and Tru Cut Core - Drainages
risk of FNAC
seeding tumours
patient preparation for drainages
- fasting for at least 6 hours
history of fluoro
- Whilhelm Conrad Roentgen
- 8 nov 1895
primary function of fluoro
- live display anatomy
- dynamic motion/ process
- interventional procedures
oldest device used for fluoroscopy
cryptoscope
effective dose of a barium enema procedure
3-6mSv
xray vs fluoro
xray
- high mA, low second
- high SNR
- low temporal resolution
fluoro
- low mA, variable second
- low SNR
- high temporal resolution
how does frame averaging affect image quality
frame averaging = decrease noise = decrease temporal resolution
components of a conventional fluoroscopic unit
- high voltage generator
- xray tube
- xray image receiver: II
- viewing system
undercouch fluoroscopy meant that detector is
on top
components of the II
- input phosphor layer
- photocathode
- focusing electrode
- vacuum enclosure
- anode
- output phosphor layer
what does the input phosphor layer consist of
cesium iodide (CsI) crystals
- prevent lateral light spread
- for scintillation
what is the function of the photocathode
- converts light photon to photoelectron
- efficiency 20%
what is the output phosphor layer made of
thin powdered phosphor
what does the output phosphor layer do
converts photoelectron back to light photon
