x-ray circuit Flashcards
the basic “on/off” switch connected to the power supply of the facility
main power switch
A device that acts in the same manner as a fuse. If the current flowing through it rises above a certain level, the _____________ flips its internal switch to open the circuit and stop the electric flow
circuit breaker
a circuit breaker acts in the same manner as a _______
fuse
A device that raises or lowers voltage in the primary circuit
auto transformer
how does an auto transformer work?
the wire is wound ly once around the magnetic core which functions as both the primary and secondary coils and operates on the principle of self-induction
A circuit made up of a mechanical or electronic device whose action is to start and stop the high voltage across the x-ray tube. It is nearly which section?
timer circuit; the primary section
A device in the primary circuit that raises voltage to the kilovolt level needed to power the x-ray tube
step-up transformer
in a step-up transformer, the primary coil is in the _________ circuit, the secondary coil in the ______________ circuit
primary, secondary
components of the primary circuit
timer circuit, step-up transformer, main power switch, circuit breaker, autotransformer
components of the secondary circuit
mA meter, rectifiers, x-ray tube (except filaments)
three main sections of the x-ray circuit
primary circuit, secondary circuit, filament circuit
A device placed in the tube circuit and used to monitor x-ray tube current
mA meter
A device that converts alternating current to direct current by allowing the current to flow through it in only one direction
rectifier
a rectifier converts ____________________________ by allowing the current to flow through it in only one direction
alternating current to direct current
An appliance for regulating the resistance and thus controlling the amount of current entering an electric circuit
rheostat
A device included in the filament circuit to lower the voltage to the filament
step down transformer
filament circuit components
rheostat, step down transformer, filaments
transformers will increase or decrease ___________
voltage
what are the three transformers used in the x-ray circuit?
autotransformer, step-up transformer, step-down transformer
A facility is generally only supplied with ___________
220V or 440V
what is the equation for the transformer law?
Vs/Vp = Ns/Np (where V=voltage and N=number of turns; s=secondary coil and p=primary coil)
if there are more turns in the secondary coil than the primary coil, Voltage in the secondary coil will ________ (_________ transformer)
increase, step-up
If there are less turns in the secondary coil than the primary coil, voltage in the secondary coil will __________ (________ transformer)
decrease, step-down
primary side of the autotransformer faces the __________; secondary side is the ____________
power source; opposite side
taps connected to the autotransformer are always on the _____________
secondary side
autotransformer is controlled by the ____________
kVp on the control panel
in an autotransformer, a series of taps connected to the secondary side allows for the __________________ to be adjusted which then adjusts the _____________
number of turns used; output charge
When the radiographer selects a kVp, he/she determines ________________________- on the secondary side of the autotransformer and with it, the output voltage that will then be applied to the ______________ of the step-up transformer.
the number of turns to be included; primary side
what is the approximate constant increase in an autotransformer?
500x
step-up transformer is also called the _____________
high-tension transformer
Used to increase volts from the autotransformer to levels suitable for the creation of X-rays
step-up transformer
what is the dividing line between the primary and secondary circuit?
step-up transformer
can you adjust the step-up transformer?
no
step-down transformer is also called the ____________
filament transformer
Used to control the degree and duration that the filament is heated
step-down transformer
The step-down transformer reduces the voltage that is supplied to the _____________________________
fine, more delicate filament wires
in the step-down transformer, because we are more concerned with the current (mA) running to the filament, the ___________ of this transformer is considered more than the ______________
output current, voltage
energy can neither be created or destroyed. The total energy of an isolated system remains constant
Law of Conservation of Energy
Ohm’s law equation
V = (I)(R); Voltage = (Amps)(Resistance or Ohms)
what is the equation to calculate the output current of a transformer
Ip/Is = Ns/Np (where I=current and N=number of turns)
To change the AC current to DC current, a device called a ___________ is used
rectifier
Although transformers in an X-ray circuit need _____ to work, the X-ray tube needs a _______________ to keep the current flow going from the anode to the cathode and electron flow from the cathode to the anode.
AC, direct current
a device that only conducts electricity in ___________________________
one direction, “a one-way door”
the rectifier most used today’s x-ray circuits is the ___________________
solid-state diode
two types of solid-state diodes
P-type crystals, N-type crystals
crystal that has an abundance of “electron traps”
P type crystals
crystal that has an abundance of freely moving electrons
N type crystals
when viewing a symbol for the solid state diode, the triangle is pointing in the direction of (electron flow/current flow)
current flow (electrons flow in the opposite way)
A diode is an electronics component made from a combination of a P-type and N-type semiconductor material, known as a _____________
p-n junction
when a diode doesn’t allow current flow in the “reverse” direction, it is called a ________
an insulator
p-type is on the __________ side
n-type is on the ___________ side
p-type is on the anode side
n-type is on the cathode side
a passive element or part of the circuit that implements electrical resistance to reduce current flow among other uses
resistor
with a rheostat, a setting of 100 mA will have ____________________________________-
ten times the resistance as a setting of 1000 mA
The purpose of the filament circuit is to “boil off” electrons from the filament wire in a process referred to as thermionic emission
thermionic emission
the rheostat controls the resistance in the _____________________ which in turn controls the amount of heating and number of electrons boiled off through thermionic emission
filament circuit and filament
A device that regulates the length of time the electrons are allowed to cross the tube and, therefore, the time x-rays are produced to create a radiographic image
exposure timer
exposure timers are usually located in the _______________
primary circuit
this timer is based on a synchronous motor which is a specialized motor designed to turn a shaft at exactly 60 cycles or revolutions per second
synchronous timers
very sophisticated and accurate and most commonly used today. Timing circuit based on the time required to charge a capacitor through a variable resistor
electric timers
special kind of electronic timer that monitors the product of mA and exposure time and terminates the exposure when the desired mAs value is attained
mAs timer
A timing device that measures the amount of radiation that reaches the IR. It automatically shuts off the exposure when the required amount of radiation intensity, Also known as a ____________
AEC timer, phototimer
