FluoroPrep Flashcards
What does automatic brightness control do?
ABC keeps the light output of the image intensifier constant over variations of patient attenuation (different tissue density and thickness)
Syllabus Page 23
Which body area has the largest distribution of fluoroscopic examinations?
GI tract (The gastrointestinal tract has the largest distribution of fluoroscopic examinations, including the barium enema, upper GI series, and KUB. Syllabus pg 1.)
This occurs when an incident x-ray photon is annihilated near the nucleus of an absorbing atom with the subsequent production of an electron and a positron.
pair production
What are the three ways in which energy is lost during x-radiation?
- photoelectric effect
- Compton scattering
- pair production
This occurs when a collision occurs between an x-ray photon and an INNER orbital electron.
photoelectric effect
This occurs when an interaction occurs between an x-ray photon and an outer orbital electron
Compton scattering
Digital fluoroscopy systems are commonly used to record images of:
vessels
How do you get a reading from a pocket ionization chamber?
They are either self-reading OR can be read by a special device.
Pocket ionization chambers discharge a capacitor by ionization of air within a chamber when in the presence of ionizing radiation. The rate of discharge depends on the intensity of the radiation.
This component changes the magnification mode by changing the field of view (FOV).
electrostatic lens
Magnification mode increases resolution from about:
4lp/mm to 6lp/mm
What is the maximum exposure rate allowed for fluoroscopic equipment manufactured after August 1, 1974, without automatic exposure controls (AEC)?
The allowable exposure rate in equipment WITHOUT automatic exposure control is 5 rads/minute.
Syllabus pg 41.
(WITH AEC, the max exposure rate is 10 rads/min)
What is the typical setting (in mA) during spot filming?
150 mA
How long does it take for a fluoroscopy table to move from the horizontal to vertical position?
20 to 30 seconds
The acceleration of the electron stream inside the image intensifier requires a potential difference (voltage) of?
25 kV
The output phosphor of an image intensifier converts ____ to ____?
electrons to light
The point in the image intensifier tube where the electrons crossover is called what?
The electronic focal point or spot
In order to prevent light from scattering back to the photocathode layer of the image intensifier, a thin sheet of aluminum is placed onto the ?
output phosphor
The input phosphor of most modern image intensifiers is made of?
cesium iodide
The output phospor of most modern image intensifiers is made of?
zinc cadmium sulfide
The electronic signal which carries the information from the television camera to the monitor is termed the?
video signal
In order to prevent the flicker effect during viewing of the television image, a technique called __ is used.
interlaced horizontal scanning is used.
The electron beam in the television camera tube is produced by?
thermionic emission
The target assembly of a television camera tube consists of?
target, signal plate, window
In the optical coupling arrangement, which is nearest the television camera tube?
camera lens
One television frame rate is equal to?
2 television fields
Horizontal television resolution is limited principally by what?
bandpass (bandwidth)
The maximum operating potential of most modern fluoroscopic x-ray tubes is approximately?
150 kVP
The target or photo-conductive layer of the vidicon tube in the television camera, which serves like tiny capcitorrs, is most often composed of?
antimony trisulfide
In the optical coupling arrangement, which is nearest the image intensifier?
objective lens
The central portion of the image intensifier tube possess the greatest?
resolution
The function of an ABC mechanism of the image intensified fluoroscopic system is to?
maintain a fixed dose rate to the image intensifier
In order to create an appearance of motion without flicker, a frame must be complete every?
1/30 sec
X-ray tube housing must be so constructed that the leakage radiation at a distance of 1m from the target cannot exceed ?
100 mR/hr
A “radiation area” is any area accessible to personnel , in which there exists radiation at such levels that a major portion of the body could receive in any one hour a dose in excess of?
5 millirems in any one hour (0.05 mSv)