Ch.2 PPT Flashcards
The ___ is heated, and electrons are emitted.
The electrons are attracted to the ___, move rapidly towards the ___, and are ___.
cathode, anode, anode, decelerated
Tungsten is a good material for the target because of 3 things:
1) high melting point
2) efficiently produces x-rays
3) high Z
What % are Bremsstrahlung interactions?
85%
What % are Characteristic interactions?
15%
Events on cathode side when preparing the tube for exposure:
- What happens to the filament?
- the heat ____ ____ ____, also called ___.
- then the electrons…
- what does the focusing cup do?
- what happens with the # of electrons?
- filament is heated
- boils off electrons, thermionic emission
- electrons gather in a cloud around the filament
- focusing cup keeps electron cloud focused together
- # of electrons in the space cloud effect is limited (space charge effect)
What happens on the anode side when preparing the tube for exposure?
- The ___ ___ begins to turn rapidly.
rotating target
Once exposure is initiated, what happens on the cathode side?
- High ___ charge strongly ___ electrons.
- electrons go toward ___.
- negative, repels
2. anode
Once exposure is initiated, what happens on the anode side?
- High ___ charge strongly ___ electrons in the tube current.
- Electrons ___ the anode.
- ___ and ___ are produced.
- positive, attracts
- strike
- heat, x-rays
Kilovoltage creates ___ ___.
potential difference
Kilovoltage determines ___ of electrons in tube current.
speed
Increasing electron speed will increase x-ray beam ___.
penetrability (quality)
Unit to measure tube current or number of electrons flowing per unit time is called.
Milliamperage (mA)
The smaller the anode angle the ___ the effective focal spot size.
smaller
Aluminum filtration added to x-ray beam to absorb low-energy x-rays is beneficial because it ___.
reduces pt exposure
Heat Units (HU) equation:
HU = mA x time x kVp x generator factor
