Introduction

Question 1

ionization

Answer 1

electron is removed –> ion pair

Question 2

ionizing radiation sources

Answer 2

cosmic, radon, imaging

Question 3

radon gas

Answer 3

largest source of natural radiation

Question 4

x-ray discovery

Answer 4

• 11/9/95, Wilhelm Roentgen

Question 5

x-ray properties

Answer 5

• penetrability
• ionizating
• fluoresce and emit light

Question 6

imaging system components

Answer 6

• tube
• operating console
• high-V generator

Question 7

x-rays are emitted..

Answer 7

isotropically (all directions)

Question 8

cathode

Answer 8

• negative end

- thoriated tungsten –> heat resistant filament

Question 9

thermionic emission

Answer 9

filament temp rises until outer shell electrons “boil off”

Question 10

focusing cup

Answer 10

(-) charged and confines accelerated electrons toward anode

Question 11

anode

Answer 11

• (+)
• target (conductor)
• dissipates heat

Question 12

rotating anodes

Answer 12

reduced heat damage to tube

Question 13

disadvantage of line-focus principle

Answer 13

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

Question 14

uniform tissue exposure

Answer 14

anode must face thinner body part

Question 15

Will the grid reduce extrafocal radiation?

Answer 15

NO

Question 16

x-ray (high voltage) generator

Answer 16

modifies incomig voltage and current

Question 17

control panel

Answer 17

technical factors (mA, kV, Time)

Question 18

transformer

Answer 18

modifies voltage

Question 19

step-up transformer

Answer 19

V increase and I decreases for greater beam energy

Question 20

step-down transformer

Answer 20

V decrease and I increase to heat cathode for thermionic emission

Question 21

rectifiers

Answer 21

AC –> DC

Question 22

high-frequency power generator

Answer 22

provides constant potential V waveform which doubles radiation

Question 23

collimator

Answer 23

restricts x-ray to target area

Question 24

added filtration

Answer 24

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

Question 25

bucky system

Answer 25

grid that removes scatter radiation

Question 26

Radiographic film

Answer 26

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

Question 27

mAs

Answer 27

• milliamperage per second

- mAs –> x-ray quantity

Question 28

kVp

Answer 28

• kilovoltage peak

- kVP –> x-ray quality (penetrability)

Question 29

4 % kVp change

Answer 29

visible film changes

Question 30

change of 5-10 kVp = …

Answer 30

50% change in mAs

Question 31

change in visible optical density

Answer 31

30 % change in mAs

Question 32

10 kVp rule

Answer 32

change kVp by 10 results in same image density change as by increasing/decreasing mAs by 50 %

Question 33

penumbra

Answer 33

• ” almost, nearly”
• blurring of image
• increasing object film distance will increase penumbra

Question 34

radiation intensity

Answer 34

inversely related to the square of the distance from the source