INTERNAL STRUCTURES (ANODE) Flashcards
It conducts electricity, radiates heat & contains the target
Anode
3 functions of Anode
Electrical Conductor
Mechanical support for the target
Thermal dissipator
3 most common Anode Material
Copper (Cu-29)
Molybdenum (Mo-42)
Graphite
used in dental x-ray imaging systems, some portable imaging systems, and other special-purpose units in which high tube current and power are not required
Stationary Anode
The area of the anode struck by the electrons from the cathode.
Target
➢ It allows the electron beam to interact with a much larger target area
➢ 3,600 - 10,000 rpm
➢ target areas of typical stationary anode (4 mm2) and rotating anode (1800 mm2) x-ray tubes with 1-mm focal spots.
Rotating Anode
The shaft between the anode & the rotor
Anode stem
Composition of Anode Stem?
Molybdenum
Characteristics: poor heat conductor
It is used to turn and power the anode
Electro Magnetic Induction Motor
2 Principal parts of electromagnetic induction motor
Stator & Rotor
Located outside the enclosure.
- Stationary coil windings (electromagnets)
Stator
Located inside the glass envelope
- Rotating part (shaft)
Rotor
Time it takes the rotor to rest after use
- Approximately 60 s
Coast time
➢ Design incorporated into x-ray tube targets
➢ Allows large area for heating while maintaining a small focal spot
Line-Focus Principle
the ability of the cone of x- rays produced to adequately cover the largest field size used
Limiting Factors
The area projected onto the patient & image receptor.
Effective Focal Spot/Effective Target Area
The area on the anode target that is exposed to electrons from the tube current
Actual Focal Spot
One unfortunate consequence of the line-focus principle
➢One unfortunate consequence of the line-focus principle is that the radiation intensity on the cathode side of the x-ray field is greater than that on the anode side.
Anode Heel Effect
➢X-rays produced in the anode but not at the focal spot
Off –Focus Radiation/Extra-focal x-rays/Undesirable radiation
it guides and aids the radiographer in using x-ray tubes and acceptable exposure levels to maximize x-ray tube life.
X-ray tube rating chart
Three types of Rating Charts
1.Radiographic Rating Chart
2.Anode Cooling Chart
3.Housing Cooling Chart
The most important as it conveys which radiographic techniques are safe and which techniques are unsafe for x-ray tube operation.
Radiographic rating chart
It is used to determine the thermal capacity of an anode and its heat dissipation characteristics
Anode Cooling Chart
➢It has the same use to anode cooling chart.
➢ Complete cooling of the housing is after a maximum heat capacity from 1 to 2 hours.
Housing Cooling Chart
