The X-ray Unit/Imaging System Flashcards
it is used to provide controlled flow of electrons that it is intense enough to produce x-ray beam
x-ray unit or imaging system
three components of xray unit
operating console
high voltage generator
xray tube
it is the part of the xray machine most familiar to the radiographer
operating console
the number of xrays; mR or mR per mAs
quantity
it is the penetrating quality of xray beam kVp or half value layer
quality
it incorporates a meter to measure the voltage provided to the x-ray machine and a control to adjust that voltage to precisely 220 volts
line compensation
it is designed to supply a precise voltage to the filament circuit and to the high voltage circuit of the xray machine
autotransformer
some older xray operating consoles have labelled major and minor kvp by selecting a combination of these controls, the radiographer can provide precisely the required kvp
kvp adjustment
it allows the voltage to be monitored before an exposure
prereading kvp meter
it is where the number of electrons emitted by the filament is determined by the temperature of the filament
mA control
as filament current increases, the filament becomes ___ and more electrons are released by _____ emission
as filament current increases, the filament becomes hotter and more electrons are released by thermionic emission
filament normally operates at the current between __ to __ amperes
filament normally operates at the current between 3 to 6 amperes
it causes the x-ray tube to emit for a specific time as determined by the radiographer or by an automatic exposure control
exposure timers
five types of timing circuits
mechanical timer
synchronous timer
electronic timer
mAs timer
automatic exposure controls
it is a timing circuit that are very simple devices used only in some portable and dental units and it operates by a clockwork
mechanical timer
it is a timing circuit that is a special type of electronic motor and is a precision device designed to drive a shaft at precisely 60 revolutions per seonds
synchronous timer
it is a timing circuit that are the most sophisticated, most complicated and most accurate of the x-ray exposure timers
electronic timer
it is a timing circuit that most xray apparatus is designed for accurate control of tube current and exposure time
mas timer
it is a timing circuit that it automatically terminates the exposure when sufficient radiation to provide the required optical density has reached the image receptor
automatic exposure controls
this evaluates the length of time that the xrays produces
evaluation timer
it is responsible for converting the low voltage from the electric power company into a kilovoltage of the proper waveform
high voltage generator
it is a step up transformer where the secondary voltage is higher than the primary voltage
high voltage transformer
what do you call a ratio of the number of secondary windings to the number of primary windings?
turn ratio
is the process of converting alternating voltage into direct voltage and therefore alternating current into direct current
rectification
represents a condition in which the voltage is not allowed to swing negatively during the negatively half of its cycle
half wave rectification
in a full wave rectified circuit the negative half cycle corresponding to the inverse voltage is reversed so that a positive voltage is always directed across the xray tube
full wave rectification
this results in pulsating xray beam
single phase power
multiple voltage waveforms are superimposed on one another, which result in a waveform that maintains a nearly constant high values
three phase power
the newest development in high voltage generator design uses a high frequency unit
high frequency generator
the parts of an xray unit are identified by their power rating in kW
power rating
power = ____ x ____
power = amperes x volts
is the variation in peak voltage waveform
voltage ripple
three phase six pulse = __% ripple
three phase six pulse = 13% ripple
three phase twelve pulse = _% pulse
three phase twelve pulse = 4% pulse
