X-ray Production and Tube Components Lecture Notes

Comprehensive vocabulary flashcards covering X-ray tube physics, history, components, and the principles of X-ray production based on the lecture transcript.

Speed of Light

The velocity at which X-ray photons travel, which is approximately $186,000\,\text{miles per second}$ or $3 \times 10^8\,\text{m/s}$.

Duality

The concept that X-rays can behave both as waves and as particles (photons).

Inverse Square Law

The physical principle stating that the intensity of X-rays varies with the square of the distance from the source.

Coolidge Tube

A hot cathode tube that used a filament to heat things quickly and reduce imaging time, though it lacked a mechanism to cool the anode.

Stationary Anode

An older type of anode used in dental imaging offices rather than modern diagnostic imaging.

Rotating Anode

A tube component used in modern diagnostic imaging and CT that spins to dissipate heat and allow for higher X-ray production.

Cathode

The negative electrode assembly of the X-ray tube that acts as the source of electrons.

Anode

The positive electrode assembly of the X-ray tube where X-rays are produced and electrons are decelerated.

Thoriated Tungsten

The material used for filament wires due to its very high melting point and low vaporization.

Thermionic Emission

The process of boiling off and releasing electrons from the surface of the filament wire.

Focusing Cup

A curved, negatively charged component made of nickel, molybdenum, or stainless steel that directs the electron stream toward the anode.

Space Charge Effect

The phenomenon where the negative charge of boiled-off electrons hanging around the filament repels further electrons, limiting the total number of X-rays produced.

Molybdenum

A material used in the focusing cup and anode stem because it can conduct electricity while dissipating heat.

Tungsten

The primary target material for anodes because it has a high atomic number of $74$ and a high melting point.

Rhenium

An alloy added to the tungsten target (typically $10\%$) to help prevent pitting on the anode surface.

Focal Spot Size

A setting determined at the control panel that selects either the small/short filament wire for detail or the large/long filament wire for larger body parts.

Spatial Resolution

The record of detail in an image, which is higher when using a small focal spot.

Focal Spot Blooming

An increase in focal spot size due to high current (MA) settings where electrons repel each other and expand the impact area.

Stators

Electromagnets located outside the glass envelope that engage with the rotor to turn the induction motor.

Potential Difference

The voltage across the cathode and anode necessary to propel electrons to a high velocity.

Line Focus Principle

The use of a beveled anode edge to allow a large actual focal spot for heat dissipation while maintaining a small effective focal spot for sharper images.

Anode Heel Effect

A variation in X-ray beam intensity where the intensity is greater at the cathode end due to absorption in the beveled edge of the anode.

Off-focus Radiation

Low-intensity X-rays produced by electrons that hit the tube in areas other than the focal track, degrading image quality.

Leakage Radiation Limit

The legal requirement that tube housing must allow no more than $100\,\text{milliretons per hour}$ at $1\,\text{meter}$ from the source.

Isotropically

The manner in which X-rays are produced in $360$ degrees.

Heat Unit (HU) Calculation

The amount of heat produced per exposure, calculated as: $kVp \times mA \times \text{seconds} \times \text{Generator Factor}$.

High Frequency Generator Factor

A constant of $1.45$ used when calculating heat units for high frequency X-ray units.

Instantaneous Load Chart

A manufacturer-provided chart showing the maximum $kVp$ and $mA$ values for a single exposure time to avoid tube damage.

Bremsstrahlung (Brems) Interaction

An interaction where an incident electron is decelerated by the nuclear force field, producing a polyenergetic X-ray photon.

Characteristic Interaction

An interaction where an incident electron collides with an inner shell (K-shell) electron, requiring at least $69\,\text{KeV}$ to $70\,\text{KeV}$ for diagnostic imaging.

X-ray Quality

The penetrating ability or energy of the X-ray beam, primarily controlled by $kVp$.

X-ray Quantity

The total number of X-ray photons in the beam, primarily controlled by $mA$ and exposure time.

Filtration

The process of removing low-energy photons from the beam, which increases beam quality but decreases total quantity.