Ch 5

Flashcards covering key vocabulary and concepts related to the x-ray tube, its components, and operational principles.

X-ray Tube

An electronic vacuum tube consisting of an anode, cathode, and induction motor, encased in a glass or metal enclosure.

Anode

The positive end of the x-ray tube that serves as the target for electron interaction to produce x-rays.

Cathode

The negative end of the x-ray tube that provides the source of electrons needed for x-ray production.

Induction Motor

A motor used to rotate the anode in a vacuum without requiring an engineering motor inside the vacuum.

Filaments

Coils of wire, typically made of tungsten, that emit electrons when heated to the point of incandescence.

Focusing Cup

A component made of nickel that surrounds the filaments, shaping the electron cloud for x-ray production.

Space Charge

A cloud of electrons formed in the focusing cup as they are boiled off the filament.

Space-Charge Effect

A phenomenon that occurs when the size of the space charge makes it difficult for further electrons to be emitted.

Thermionic Emission

The process by which electrons are boiled off the filament due to high temperatures.

Line-Focus Principle

A method that allows maintenance of a large actual focal spot while creating a smaller effective focal spot.

Anode Heel Effect

A variation in x-ray intensity caused by absorption of some x-rays in the target heel.

Copper

A material used in the x-ray tube for its excellent thermal and electrical conductivity.

Molybdenum

A material that serves as the base and core of the rotating anode due to its low thermal conductivity.

Tungsten

A metal with a high melting point and high atomic number (74), used for the anode target due to its efficiency in x-ray production.

Rhenium

An element that may be added to tungsten to enhance thermal capacity and tensile strength.

Autotransformer

A transformer that provides a selected voltage to the x-ray tube.

Step-Up Transformer

A transformer that increases voltage from the autotransformer to the x-ray tube.

Rectifier Bank

A series of components that convert AC to DC for use in the x-ray tube.

Heat Units

A measure of the heat generated and stored in the x-ray tube calculated as kVp × mA × s × c.

Quality Control

Procedures that ensure the safe operation and maintenance of the x-ray unit.

Cooling Fans

Devices that facilitate convection heat transfer, cooling the x-ray tube.

Cooling Oil

Fluids used in the housing of the x-ray tube to absorb heat.

Electrical Insulation

Materials used to prevent electrical discharge and ensure safety in components.

Lead-Lined Structure

Protective housing designed to absorb stray photons and enhance safety.

Dual-Focus Tubes

X-ray tubes that feature two filaments for varying exposure sizes.

Induction Motor Parts

The stator and rotor; stator consists of electromagnets, rotor is made with an iron core.

Voltage

An electric potential difference that accelerates electrons in the x-ray tube.

Kinetic Energy

Energy that filament electrons acquire in the x-ray production process.

Current

The flow of electric charge that heats the filament to induce thermionic emission.

Filament Circuit

The pathway where power is diverted to heat the cathode filament.

High-Voltage Cables

Electrical cables that should not be used as handles due to high voltage risks.

Heat Transfer Processes

Conduction, radiation, and convection used to manage heat in the x-ray tube.

Safe Exposure Techniques

Protocols to prevent overheating and prolong the life of the x-ray tube.

Routine Maintenance

Regular procedures required to maintain the x-ray tube's optimal function.

Cautions for Operation

Safety measures regarding heat and proper handling of the x-ray tube assembly.

Conduction

The transfer of heat through materials in direct contact.

Radiation

The emission of energy as electromagnetic waves or particles.

Convection

The transfer of heat through the movement of fluids, such as air.

Borate Glass

Material used for glass envelopes due to its heat resistance.

Effective Focal Spot Size

The size of the x-ray beam as seen by the patient, influenced by anode angle.