xray circuit

Main circuit supplies the tube with

properly modified power that will lead to the xray production

Filament circuit supplies the filament of the tube with

properly modified power to create thermionic emission

with modern systems, the incoming line gets supplied with

three-phase power

primary circuit is

low voltage

secondary circuit is

high voltage

the primary and secondary circuit make up the

main circuit

the complete basic circuit is made up of

main breakers, exposure switch, autotransformer, timer circuit, high voltage step up transformer, four diode rectification circuit, filament circuit variable resistance, filament step-down

The circuit must boost the

voltage to the kV range necessary for x-ray production

The circuit must permit the technologist to

adjust the amperage, voltage and length of exposure

The main switch and circuit breakers are usually

enclosed in an electrical power box

the exposure switch permits

current to flow through the circuit

the timer circuit ends the exposure

at a preset time

the exposure switch must be held until

both the audible and visible indicators (buzzer and light) have stopped

holding the exposure switch lets the current flow and activates the

rotating anode

exposure switch half depression

activates anode (rotoring)

exposure switch fully depressed

intitates the exposure

minimum length of the portable exposure switch cord

6ft

switches must be

dead-man type

main breaker is where the

alternating current is coming in

auto transformer

controlled by the kVp selectors on the control console, modifies incoming-line voltage in anticipation of kV that will be produced by step up transformer

some units divide kVp adjustments into

minor (1-2) and major (10) change in units

electronic timers

capable of accurate exposures as short as 0.001 second, microprocessor controlled, contained in most radiographic equipment

AEC timer function by

measuring a preset quantity of radiation and breaking the timer circuit when a dose sufficient to produce the desired exposure is reached

mAs timer

used in capacitor discharge unit to monitor product of mA and time on secondary side of high voltage step up transformer, interrupts circuit when mAs reached, falling load generator, after secondary coil in high volt

all AEC have a minimum reaction time (response time)

determined by the length of time necessary for the AEC to respons to the radiation and terminate exposure, minimum reaction time is shortest time for cells to decide to stop exposure

backup timer

terminates exposure at specified time if AEC fails, automatic termination at 600 mAs when above 50 kVp

autotransformer is controlled by the

kVp selection

timer circuit is wired between

autotransformer and step up transformer

high voltage step up transformer will

boost the voltage to desired kVp set

four diode rectification circuit

changes the incoming alternating current to direct current that the tube needs

the filament circuit

low voltage, modifies incoming power to produce thermionic emission, 3-5 amp and 5-15 volts, mA controller

why does increasing amperage decrease voltage

to balance the two, P = IV

The step-down reduces the V and increases the current (amps) in response to the

rheostat (variable resistor)

filament circuit variable resistance is controlled by the

mA set at the control panel

the filament step down transformer give the filament

high amperage needed to heat the filament

rotor stator

activated by the tech when the two step button is halfway depressed, what causes the anode to rotate during x-ray production

diagnostic xray range of exposure is approximately

10-1200 mA, 0.001-10 seconds, 25-150 kVp

What device in the x-ray circuit controls kVp?

autotransformer

What device in the x-ray circuit controls mA?

step down transformer

What device in the x-ray circuit controls time?

exposure timer

What device in the x-ray circuit controls rectification?

the number of diodes

At what point in the x-ray circuit is the rectification circuit located?

between the step up transformer and the xray tube

To protect the radiographer from electrical shock during x-ray exposures,
a. Operator controls are on the high voltage side of the circuit
b. The operator stands on a grounded rubber mat
c. Release of the switch initiates the exposure sequence
d. The mA and kVp selections are on the low voltage side of the circuit

The mA and kVp selections are on the low voltage side of the circuit

All of the following are radiographer-operated controls EXCEPT
a. kVp selection
b. Timer selection
c. Rotor speed
d. mA selection

Rotor speed