Fluoroscopy Flashcards
Real time imaging is usually considered to be
30 frames per second
Converts the absorbed incident xrays into light which in turn releases electrons
Input layer
Accelerates and focuses the electrons emitted by the input layer onto output layer
Electron optics system
Converts the accelerated electrons into a visible light image
Output phosphor
4 different layers of the input screen include the
Vaccum window
Support layer
Input phosphor
Photocathode
Thin aluminum window that is part of the vacuum containment vessel
Vacuum window
Thin layer of antimony and alkali metals that emits electrons when struck by visible light
Photocathode
Kinetic energy of each electron is dramatically increased by acceleration due to the voltage difference between cathode and anode, resulting in
Electronic gain
Produces continuous xray beam typically using 0.5 to 6 mA
Continuous fluoroscopy
With _____ fluoroscopy, the exposure time ranges from about 3-10 ms instead of 33ms, which reduces blurring from patient motion
Pulsed
Offers better image quality at the same average dose rates
Pulsed fluoroscopy
Continuously displays the last acquired image or set of images on the fluoroscopy monitor
Last frame hold
Motorized rotation of about 220 degrees around the patient which allows two-dimensional projection images to be acquired at many different angles around the patient
C-arm CT
Contrast resolution of fluoroscopy compared fo radiography is ____, chiefly due to the low SNR
Low
Xray scatter from the patient is most intense on what side of the patient
Entrant side
Mandatory frame rate used in cineradiography operations to capture injected contrast medium as it moves thru the vessels in the rapidly beating heart
High frame rate of 15-60 FPS
Chiefly uses fluoroscopy to guide pacing and recording electrodes that are introduced into the heart to stimulate and measure the electrical properties of various cardiac control functions
Cardiology electrophysiology laboratory
Systems with one patient table but with two complete imaging chains
Biplane angiographic systems
Maximum permissible entrance exposure rate to the patient for normal fluoroscopy is
87.3 mGy/m
For especially activated fluoroscopy, the maximum exposure rate allowable is
175 mGy/m
Dose rates are evaluated in fluoroscopy by using a tissue-equivalent phantom made of a material such as
Polymethyl methacrylate /lucite or perspex
Typical entrance rates for fluoroscopic detectors range from
8.7 to 44 nGy
As a rule of thumb, standing 1 m from the patient the fluoroscopist recieves from scattered radiation approximately _______ of the exposure incident upon the patient
1/1,000
Composed of both leakage and scatter radiation
Stray radiation
It is customary to wear a single dosimeter at ____ level, _____ of the protective aron
Collar level, in front of the apron
Image quality with high mA and constant kV
Better (lower image noise)
