Xray tube Part 2 Flashcards
Principal parts of induction motor
Rotor
Stator
Used to turn the anode
Induction motor
Comsisting of series of electromagnets equally spaced around the neck of the tube
Stator
Electromechanical coil of copper wire that is connected to a power supply
Stator
Sends pulses of energy to the stator
Rotor controller
Wire that transfer rotor controller power to stator
Stator cord
Shaft inside the enclose made of copper and soft iron
Rotor
Production of voltage across a conductor moving through a magnetic field
Electromagnetic induction
This allows the rotor to accelerate to its designated rpm while the filament is heated
Exposure switch
Where the high voltage electrons hit the anode from which xrays ate emitted
Focal spot / focal point / focus / target
Area on the target that is exposed to electrons
Actual focal spot
The area projected onto the patient
Effective focal spot
The ______ the focal spot , tge better the spatial resolution of the image
Smaller
Incorporated into the xray tube targets allowing a large area for heating w/ small focal spot
Line focus principle
Angling the target is also
Line focus principle
Diagnosing tube target angles
5 to 20 deg
Used to reduced the effective area of the focal spot
Line focus principle
As the angle decreases, effective focal spot
Decreases
Electrons can rebound and interact with other areas
Off focal radiation
Diaphragm is placed between the tube and the collimator to reduce off focal rays
Control off focal radiation
Produces two focal spot sizes because of two different target angles on the anode
Biangular targets
The radiation intensity on the cathode side of the xray field is greater that the on the anode side
Anode heel effect
Primarily under the control of rad tech
Xray tube life
Three forms of cooling
Radiation
Conduction
Convection
The anode may glow red hot
Radiation
Heat is conducted through molybdenum
Conduction
Heated glass enclosure raises temperature of the oil bath
Convection
Maximum radiographic techniques should never be applied to
Cold anode
Xray tube failure
Thermal characteristics Maintain anode elevated temperature Bearing damage Prolonged heat Electron arcing from filament
Chart that guide radtech in use of xray tubes
Xray tube rating charts
3 types of xray rating charts
Radiographic rating chart
Anode cooling chart
Housing cooling chart
Comveys which radiographic technoque is safe ang unsafe
Radiographic rating chart
Guide the most common technical factor combination
Radiographic rating chart
Anode has a limited capacity for storing heat
Anode cooling chart
Thermal energy in xray is measured
Heat units
Single phase formula
HU = kVp x ma x s
Three phase / high frequency
HU = 1.4 x kVp x mA x s
Used to determine the length of the time for complete cooling
Anode cooling chart
It would take ____ to cool the anode
15 mins
Tube housing have capacity of
1 to 1.5 million HU
Anode has the capacity of
350,000 HU
Complete cooling of the housing
1 to 2 hours
Calculation of time necessary for the housing to cool
Housing cooling chart
Extending tube life
Warm up the anode Dont hold the rotor switch unnecessarily Lower mAs Lower speed rotor Dont make repeated exposure Dont rotor the tube housing rapidly Dont use a tube when you hear rotor bearings
