chapter 5 and 6 Flashcards
kVp
- kilo volt peak
- the highest voltage applied across the X-Ray tube
mAs
- milliamps per second
- current across the filament of X-Ray tube times the time the X-Rays are turned on (exposure time)
transformer
- definition
- equation
changes voltage to desired level (current changes in opposite direction)
- Vs/Vp = Ns/Np
HV transformer
convert household voltage to very high voltage
rectifier
converts AC voltage to DC
filter
thin wall designed to allow x-rays above a certain energy to escape
cathode
- definition
- location
- 2 parts
- source of e-
- negative side of the x-ray tube
- filament and focusing cup
filament
coil of wire that emits electrons when heated
focusing cup
-negatively charged so that it focuses the electron beam to a small area of the anode
anode
- location
- 2 types
- positive side
- stationary and rotating
stationary anode
used where high tube current and power are not required
-dentist
rotating anode
used in general purpose x-ray tubes because the tubes must be capable of producing high-intensity x-ray beams in a short times
target
- definition
- made of
area of the anode struck by the electrons from the cathide
-made of tungsten
protective housing
shields most x-rays except for primary beam and leakage
-filter and collimator
collimator
shields and narrows primary beam
cooling mechanisms
fan or copper
copper
conducts heat away from target
fan
air or liquid: convection cooling
3 cooling methods
radiation, conduction, convection
radiation
glowing filament (infrared rays)
convection
flowing air, water or oil
conduction
located inside tube (copper)
how can the focal spot be reduced in size
by the angulation of the anode
common cause of x-ray tube failure
tungsten vaporization
