Unit 4: Conventional Fluoro and Digital Fluoro + Radiation Safety Flashcards
define dynamic imaging:
imaging done through motion
fluoroscopy is a __________ study.
dynamic
give an example of a static study:
spot films
Who created fluoroscopy and when?
Thomas Edison in 1896
Who should fluoro?
a radiologist or PA or a tech under guidance of a radiologist or PA
the fluoro/image intensification tube operates on __________ mA.
0.5 - 3.0
Overhead/static exposures range from __________ mA.
25-1000
fixed fluoro tubes should have how much SSD?
15”
where is the image intensifier?
where is the x-ray tube?
above the pt
under the table
what was the first generation of fluoro?
what did they use?
conventional fluoroscopes
yellow-green phosphors such as barium lead sulfate or zinc cadmium sulfide
for conventional, fluoroscopists required how much dark adaptation of the eyes prior to the exam?
20 mins
night vision is made possible by __________ located primarily on the periphery of the retina.
rods (scotopic vision)
conventional fluoroscopes used __________________ and what did this do?
mirror optics; brought the image somewhere else if you weren’t right in front of the tube
conventional fluoroscopes did not allow for __________________
multiple viewing
image intensification tubes developed in:
1948
digital fluoroscopic systems predominate by ________.
they included _____________ and ___________________________.
2005;
TFT matrices, post processing capabilities
what was second generation fluoro?
image intensification
image intensification gave us __________________ instead of yellow green images.
gray scale
what were some advantages of image intensified fluoro?
brighter image (500-8000x)
less pt dose
allowed for cone vision
not as much radiation needed on front end
remote viewing (more than one)
What were the advantages of using CsI as an IP over zinc cadmium sulfide?
less pt dose
better spatial resolution
brighter image
describe the basic chain of events taking place in an image intensifier:
- x-rays exit pt and interact with the cesium iodide IP which emits light
- the light is converted into electrons/electronic image by the photocathode
- the electrons travel from cathode side to anode side through electron stream by a PD of about 25 kVp
- the electrostatic lenses focus the electrons and bring them closer to a focal point
- the OP made of zinc cadmium sulfide converts the electrons back into light
the process of converting light into electrons:
photoemission
digital fluoroscopy uses ____________ generator and has ________________ fluoroscopy mode.
high-power; pulsed progressive
for digital fluoro, the image intensifier OP screen is coupled to ________ and ____________________.
CCD/TFT; flat panel display
first generation digital still had the _________________ but now ___________________ are coupled to the OP phosphor.
imaging intensifier; CCD with fiber optics
what is used in digital fluoro to generate an electronic signal from the light output signal?
where is this signal then sent?
CCD
ADC to be displayed on monitor
what are the advantages of CCD’s in medical imaging?
high spatial resolution
high SNR
high DQE
no warm-up
no maintenance
unlimited life
lower pt dose
what is last image hold?
what is it for?
automatic storage of the last image that was displayed on the monitor
a dose saving feature
No light conversion step and photons directly converted into electrons and sent to TFT array and ADC involves what in digital fluoro?
flat panel detectors
Describe the relationship between kVp and mAs during fluoroscopy:
if you increase kVp, you have to lower mAs and vice versa
reducing kVp during fluoro will:
increase pt dose
What is the required SSD for “fixed fluoro”?
15”
What is the required SSD for “portable fluoro”?
12”
What is a dead man switch?
pedal that when pressed will fluoro and when released, fluoro stops
the fluoro x-ray tube filtration is the same as overhead tube, but can have ______________ added to harden the beam
copper filters
what is the max exposure rate by law?
88 mGy/min
Which method of gonadal shielding is best for use during fluoro?
flat contact shielding
What are the Cardinal Principles of Radiation Protection?
minimize time
maximize distance
maximize shielding
for the bucky slot cover and the lead drape, how much is required?
0.25 mm pb equiv
for the lead apron and thyroid shield, how much is required?
0.5 mm pb equiv
what is a radiographer’s responsibility in fluoro?
inform others in the room to wear lead apron
what is pulsed fluoroscopic exposure?
where the beam is emitted as a series of short pulses instead of continuously
during a fluoroscopy where is the most ideal position for the tech to stand?
in the room, as far from the pt as practical
