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Flashcards in Introduction Deck (34)
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1

ionization

electron is removed --> ion pair

2

ionizing radiation sources

cosmic, radon, imaging

3

radon gas

largest source of natural radiation

4

x-ray discovery

- 11/9/95, Wilhelm Roentgen

5

x-ray properties

- penetrability
- ionizating
- fluoresce and emit light

6

imaging system components

- tube
- operating console
- high-V generator

7

x-rays are emitted..

isotropically (all directions)

8

cathode

- negative end
- thoriated tungsten --> heat resistant filament

9

thermionic emission

filament temp rises until outer shell electrons "boil off"

10

focusing cup

(-) charged and confines accelerated electrons toward anode

11

anode

- (+)
- target (conductor)
- dissipates heat

12

rotating anodes

reduced heat damage to tube

13

disadvantage of line-focus principle

anode heel-effect: electrons interact with target at various depths

14

uniform tissue exposure

anode must face thinner body part

15

Will the grid reduce extrafocal radiation?

NO

16

x-ray (high voltage) generator

modifies incomig voltage and current

17

control panel

technical factors (mA, kV, Time)

18

transformer

modifies voltage

19

step-up transformer

V increase and I decreases for greater beam energy

20

step-down transformer

V decrease and I increase to heat cathode for thermionic emission

21

rectifiers

AC --> DC

22

high-frequency power generator

provides constant potential V waveform which doubles radiation

23

collimator

restricts x-ray to target area

24

added filtration

aluminum filters to harden beam and improve penetrability and lessen scatter radiation

25

bucky system

grid that removes scatter radiation

26

Radiographic film

polyester and coated with emulsion containing silver halide crystals (SHC)

27

mAs

- milliamperage per second
- mAs --> x-ray quantity

28

kVp

- kilovoltage peak
- kVP --> x-ray quality (penetrability)

29

4 % kVp change

visible film changes

30

change of 5-10 kVp = ...

50% change in mAs