X-Ray Circuit Basics

Questions and Answers

Name the 2 subdivisions of the x-ray circuit.

Main circuit, Filament circuit

Define/describe the Main circuit.

Supplies x-ray tube with high voltage (kVp), low amperage (mA) needed for x-ray production.

Define/describe the Filament Circuit.

Supplies the filament in the cathode with ~10 volts, ~5 amps for thermionic emission.

What are the 2 parts/sides of the main circuit called?

Primary low voltage side, Secondary high voltage side Signup and view all the answers

Name the 5 components that make up the primary side of the main circuit.

Main breaker, Exposure switch, Autotransformer, Timer circuit, Primary side of high voltage step-up transformer Signup and view all the answers

Name the 4 components that make up the secondary side of the main circuit.

Secondary side of the step-up transformer, Rectification system, X-ray tube, Rotor stator Signup and view all the answers

What does the main breaker do and where is it usually located? What is the main power being supplied to our rooms for x-ray?

Controls incoming power source; usually located by the control panel in electrical power box. 220 volts, 60 Hz AC. Signup and view all the answers

What does the exposure switch do? Where is it located/connected to? What kind of switch is it?

Remote control switch that permits current flow in the circuit; interconnected with anode rotor and timer circuitry; 'dead-man' type switch. Signup and view all the answers

What is attached in parallel to an Autotransformer?

Kilovolt meter Signup and view all the answers

Describe/discuss the Autotransformer.

Modifies incoming line voltage (220 V) in anticipation of the kVp that will be produced by the step-up transformer; secondary side taps controlled by kVp selector; kilovolt meter attached in parallel. Signup and view all the answers

What does the Timer Circuit do?

Regulates length of time that current runs through the x-ray tube. Signup and view all the answers

What is the function of the Primary side of high voltage step-up transformer, and what does this specific component mark regarding the main circuit?

Marks the separation of the primary & secondary side of the main x-ray circuit; function is to increase modified voltage from the autotransformer to levels high enough for x-ray production. Signup and view all the answers

What component marks the separation of the primary and secondary side of the main x-ray circuit?

Primary side of high voltage step-up transformer Signup and view all the answers

What is attached in series to the Secondary side of the step-up transformer?

mA meter Signup and view all the answers

What does the Rectification System do?

Converts AC to DC for x-ray production. Signup and view all the answers

What is the function of the rotor stator?

Controls rotation of the anode for x-ray exposure. Signup and view all the answers

What is the function of the Filament Circuit?

Thermionic emission; incoming line must be modified to 3-5 amps, 6-12 volts. Signup and view all the answers

For Thermionic emission to work, the incoming line in the circuit must be modified to to amps and _ to _____ volts.

3-5, 6-12 Signup and view all the answers

Name the 2 components of the Filament Circuit.

Variable resistor (rheostat), Step-down transformer Signup and view all the answers

What is another name for the rheostat?

Variable resistor Signup and view all the answers

What is another name for the variable resistor?

Rheostat Signup and view all the answers

Describe/Discuss Variable resistor (rheostat).

Controlled by mA selector; varies filament current; common increments range from 50 to 1200; filament ammeter attached in series. Signup and view all the answers

What component of the x-ray circuit is controlled by mA selector?

Rheostat/variable resistor Signup and view all the answers

What does the step-down transformer do in the filament circuit?

Reduces incoming line voltage to 6-12 necessary for thermionic emission. Signup and view all the answers

Name the 5 common diagnostic x-ray console controls that are controlled by the technologists.

kVp selection, mA selection, time selection, rotor switch, exposure switch Signup and view all the answers

For kVp control selection, what factor does it effect? What circuit element does it control? and where is it located within the x-ray circuit?

kVp level; autotransformers; between incoming line and exposure switch Signup and view all the answers

For mA control selection, what factor does it effect? What circuit element does it control? and where is it located within the x-ray circuit?

Filament current; variable resistor (rheostat); in filament circuit between incoming line and step down Signup and view all the answers

For control of time selection, what factor does it effect? What circuit element does it control? and where is it located within the x-ray circuit?

Length of exposure; timer circuit; between exposure switch and step up Signup and view all the answers

For control of rotor switch, what factor does it effect? What circuit element does it control? and where is it located within the x-ray circuit?

Speed of rotating anode; stator; separate circuit from stator of anode motor Signup and view all the answers

For control of exposure switch, what factor does it effect? What circuit element does it control? and where is it located within the x-ray circuit?

Moment of exposure; switch; between autotransformer and timer circuit Signup and view all the answers

What does the timer circuit control?

Controls the length of x-ray exposure. Signup and view all the answers

Where is the timer circuit located?

Usually located in the primary side of the main circuit. Signup and view all the answers

Name the 4 types of timers.

Synchronous timers, Electronic timers, mAs timer, Automatic exposure control (AEC) Signup and view all the answers

Describe/define Electronic timers.

Most widely used today; extremely accurate exposures as short as 1 msec (0.001 sec); exposure length is based on the time it takes to charge a capacitor through a variable resistor, once charge is complete, exposure is terminated; higher time setting increases resistance, increases time it takes to charge the capacitor. Signup and view all the answers

Name the lettered areas of the x-ray circuit.

a. Main breaker, b. Autotransformer (secondary side), c. Transformer step-up, d. Full wave rectifier, e. X-ray tube Signup and view all the answers

Name the numbered areas of the x-ray circuit.

<ol> <li>Primary side of main circuit, 2. Secondary side of main circuit, 3. Filament circuit, 4. Power/main breaker, 5. Autotransformer, 6. Kilovoltmeter, 7. Exposure switch, 8. Timer circuit, 9. Step-up transformer, 10. Full wave rectifier, 11. Rotor stator, 12. X-ray tube, 13. Rheostat or variable resistor, 14. Filament ammeter, 15. Step-down transformer</li> </ol> Signup and view all the answers

Which timer is the only timer located on the secondary side of the main circuit?

mAs timer Signup and view all the answers

What kind of timer works based on exposure length and the time it takes to charge a capacitor through a variable resistor and once charge is complete, exposure is terminated?

Electronic timers Signup and view all the answers

Describe/define Automatic exposure control (AEC).

Unique in that this timer uses the patient's body thickness/composition as the variable in determining when to terminate the exposure; AEC uses an 'ionization chamber'; must be calibrated to the image receptor speed class used. Signup and view all the answers

What is an ionization chamber and how does it work?

A radiolucent device placed between the patient and the image receptor; x-rays ionize air in chamber, liberating electrons, which become an electric charge; this electric charge is the signal which terminates the exposure. Signup and view all the answers

What type of timer uses an ionization chamber?

Automatic exposure control Signup and view all the answers

State the 2 main electrical requirements of an x-ray tube.

Main circuit - high voltage, low amperage; Filament circuit - low voltage to filament. Signup and view all the answers

An x-ray generator converts __ energy into energy.

Electrical, X-ray Signup and view all the answers

The part of the x-ray generator that supplies the high voltage necessary between the cathode and the anode is called the _______ circuit.

Main Signup and view all the answers

The part of the x-ray generator that supplies current and voltage to the cathode of the x-ray tube is called the __________ circuit.

Filament Signup and view all the answers

The main power line in a hospital is usually a volt, hertz A.C.source.

220, 60 Signup and view all the answers

Each of the hot wires in the main power line varies up to __________ volts positive or negative, with respect to the neutral wire.

110 Signup and view all the answers

The turns ratio of an ____________ can be varied by selecting the number of turns between connectors on a single coil.

Autotransformer Signup and view all the answers

The voltage on the secondary side of the autotransformer shown below will be _________ (higher/lower) when the selector is at position 2 than when it's at position 5.

Higher Signup and view all the answers

To raise the voltage higher than the autotransformer is capable of raising it, a _____________ transformer is included in the tube circuit.

Step-up Signup and view all the answers

The autotransformer is connected at the __________ (primary/secondary) side of the step-up transformer.

Primary Signup and view all the answers

If a step-up transformer has a turns ratio of 500 to 1 and a voltage of 220 volts exists on the primary side, then the voltage of ____________ volts will exist on the secondary side.

110,000 Signup and view all the answers

An x-ray tube operates most efficiently with (AC/DC), but the auto-transformer and step-up transformer require __ (AC/DC).

DC, AC Signup and view all the answers

The circuit component that changes A.C. to D.C. is called a ___________.

Rectifier Signup and view all the answers

A __________ is a device that allows current to flow in one direction only.

Diode Signup and view all the answers

The two types of diodes are:

Tube type = Classic design Solid state = Modern design Signup and view all the answers

The purpose of the ____________ in the filament circuit is to allow the operator to vary the current in the circuit.

Rheostat or variable resistor Signup and view all the answers

The position of the removable contact on the rheostat determines the amount of _________ and indirectly, the current in the filament circuit.

Resistance Signup and view all the answers

The filament circuit contains a ____________ (step up/step down) transformer.

Step-down Signup and view all the answers

The tube and filament circuit are connected at what part of the x-ray tube?

Cathode Signup and view all the answers

Study Notes

X-Ray Circuit Overview

The x-ray circuit is divided into two main subdivisions: the main circuit and the filament circuit.
The main circuit supplies high voltage (kVp) and low amperage (mA) to the x-ray tube for producing x-rays.

Main Circuit Components

Comprised of two sides: primary low voltage side and secondary high voltage side.
Key components of the primary side: main breaker, exposure switch, autotransformer, timer circuit, and primary side of the high voltage step-up transformer.
Key components of the secondary side: secondary side of the step-up transformer, rectification system, x-ray tube, and rotor stator.

Filament Circuit Functionality

Supplies approximately 10 volts and 5 amps to the filament in the cathode, enabling thermionic emission.
Two main components include a variable resistor (rheostat) and a step-down transformer.

Voltage and Current Control

Required modifications for thermionic emission are 3-5 amps and 6-12 volts.
The autotransformer adjusts the incoming line voltage (220 V) based on kVp to produce the necessary voltage for the x-ray exposure.
The timer circuit regulates the time duration the current flows through the x-ray tube, typically located on the primary side.

Exposure Controls

Technologists control various functions via console controls: kVp selection, mA selection, time selection, rotor switch, and exposure switch.
Electronic timers are commonly used, offering precise exposures based on capacitor charging time.

Rectification System

Converts alternating current (AC) to direct current (DC) necessary for effective x-ray production.
The diode is a crucial component; it only allows current flow in a single direction.

Additional Circuit Details

Each hot wire in the main power line can vary by 110 volts relative to the neutral wire.
The step-up transformer is crucial for increasing voltage beyond what the autotransformer can achieve.
The x-ray tube operates efficiently with DC, while transformers require AC inputs.

Ionization Chamber and AEC

The automatic exposure control (AEC) uses an ionization chamber to determine exposure termination based on the patient's body thickness and composition.
The ionization chamber liberates electrons when ionized by x-rays, generating an electric charge that signals exposure stop.

Summary of Terminology

The main circuit provides the necessary high voltage for the x-ray tube, while the filament circuit supplies lower voltage and current specifically for the filament.
Critical terms include: autotransformer, step-down transformer, rheostat (variable resistor), and diode.

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Description

Explore the fundamentals of x-ray circuits through this quiz. Learn about the main circuit and filament circuit, along with their functions in x-ray production. Perfect for students studying radiology or imaging technology.