Diagnostic X-Ray Circuit: Primary, Secondary and Filament Systems

What are the two main divisions of the x-ray circuit?

The main circuit and the filament circuit.

What does the main circuit supply?

It supplies the tube with properly modified power for x-ray production.

What does the filament circuit supply?

It supplies the filament of the tube with properly modified power to create thermionic emission.

What type of power do modern x-ray systems use?

Three-phase power.

What components make up the complete basic x-ray circuit?

Main breaker, exposure switch, autotransformer, timer circuit, high-voltage step-up transformer, four-diode rectification circuit, filament circuit variable resistance, filament step-down transformer, x-ray tube, rotor stator.

What is the function of the exposure switch in the x-ray circuit?

It allows current to flow and initiates the exposure when fully depressed.

What must the exposure switch be designed to prevent?

It must prevent the operator from being exposed to radiation.

What is the purpose of the autotransformer in the x-ray circuit?

It modifies the incoming-line voltage in anticipation of the kV produced by the step-up transformer.

What type of timers are capable of accurate exposures as short as 0.001 seconds?

Electronic timers.

What does the milliamperage-second (mAs) timer monitor?

It monitors the product of mA and time on the secondary side of the high voltage step-up transformer.

What is the minimum reaction time in Automatic Exposure Control (AEC) systems?

It is the shortest time it takes for the cells to decide to stop the exposure.

What is the role of the high-voltage step-up transformer?

It boosts the voltage up to the desired kilovoltage set.

What does the four-diode rectification circuit do?

It changes the incoming alternating current to direct current needed by the x-ray tube.

What does the filament circuit modify?

It modifies the incoming-line power to produce thermionic emission from the filament wire.

What is the typical amperage and voltage supplied by the filament circuit?

About 3-5 amperes and 5-15 volts.

What component regulates the amperage supplied to the filament in the x-ray tube?

A variable resistor (current control device).

What is the purpose of the rheostat in the filament circuit?

It adjusts the mA at the control panel to regulate the quantity of electrons available at the filament.

What happens when the exposure switch is depressed halfway?

It activates the anode rotation.

What is the diagnostic x-ray range of exposure for mA?

Approximately 10 - 1,200 mA.

What is the purpose of having operator controls on the low voltage side of the circuit?

To protect operators from high-voltage shock hazards.

What is the function of the timer circuit in the x-ray circuit?

It ends the exposure at a preset time.

What is the recommended action for extending tube life during exposure?

Fully depress the exposure switch in one motion.

What device controls the kilovoltage peak (kVp) in the x-ray circuit?

The autotransformer.

What device controls the milliamperage (mA) in the x-ray circuit?

The variable resistor in the filament circuit.

What device controls the time in the x-ray circuit?

The timer circuit.

What device is responsible for rectification in the x-ray circuit?

The four-diode rectification circuit.

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

After the high-voltage step-up transformer.

Which of the following is NOT a radiographer-operated control?

Rotor speed.