QO Study Guide - Intro/Ch.1/Ch.2

Question 1

Photoelectric effect

Answer 1

Gamma ray collides with electron and removes it from orbit around nucleus

All energy is absorbed

Question 2

Compton effect

Answer 2

Gamma ray collides with electron and removes it from orbit around nucleus

Remaining energy scatters and continues to collide with other electrons

Question 3

Ionization

Answer 3

The creation of ions by stripping electrons from atoms

Question 4

Ion pair

Answer 4

The ejected electron carries a negative charge, and the remaining atom carries a positive charge

Question 5

Prompt health effects

Answer 5

Occur within hours, days or weeks

Radiation burns and radiation sickness

Question 6

Effect of 250mSv dose

Answer 6

No obvious injury

Question 7

Effect of 500mSv dose

Answer 7

Temporary blood changes, no serious injury

Question 8

Effect of 1000mSv (1Sv) dose

Answer 8

Blood and cell changes, some injury, no disability

Question 9

Effect of 2Sv dose

Answer 9

Injury, possible disability

Question 10

Effect of 5Sv dose

Answer 10

Fatal to 50% of people

Question 11

Effect of 10Sv dose

Answer 11

Fatal to 100% of people

Question 12

Delayed health effects

Answer 12

Effects which take many years to appear

Cancer

Genetic defects in children of people exposed to radiation

Question 13

Survey meter

Answer 13

Measures and displays radiation dose rate

Question 14

Personal dosimeters

Answer 14

Measure absorbed dose

DRD and TLD

Question 15

Direct reading dosimeter (DRD)

Answer 15

Ionization chamber which measures and displays absorbed dose

Question 16

Thermo-luminescent dosimeter (TLD)

Answer 16

Measures absorbed dose over period of time it is worn

Question 17

Personal alarming dosimeter (PAD)

Answer 17

Sound an alarm if high dose rate is measured

Question 18

ALARA

Answer 18

Radiation safety principle of keeping dose As Low As Reasonably Achievable

Question 19

Three basic ways to lower dose

Answer 19

Time: don’t stay near the source longer than necessary

Distance: stay as far away from the source as you can

Shielding: use shielding between yourself and the source

Question 20

Formula to calculate dose

Answer 20

Dose rate × Time

Question 21

Unit prefixes

Answer 21

Tera - T - 10^12
Giga - G - 10^9
Mega - M - 10^6
Kilo - k - 10^3
Milli - m - 10^-3
Micro - u - 10^-6
Nano - n - 10^-9

Question 22

Calculating dose rate

Answer 22

Output factor × source activity

Question 23

Ir192 and Co60 output factors

Answer 23

iridium 192 - 0.15 mSv/hr per gigabecquerel at 1 metre

Cobalt 60 - 0.36 mSv/hr per gigabecquerel at 1 metre

Question 24

Common shielding materials

Answer 24

Depleted uranium
Tungsten
Lead
Steel
Concrete

More dense = more effective

Question 25

Collimator

Answer 25

Small piece of lead, uranium, or tungsten that partially surrounds the source to absorb radiation not directed toward the object being radiographed.

Question 26

Half value layer

Answer 26

Thickness of a given material required to reduce the dose rate to one half of its original value.

Question 27

Tenth value layer

Answer 27

Thickness of a given material required to reduce the dose rate to one tenth of its original value.

Question 28

HVL formula

Answer 28

Dose rate = known dose ÷ 2^ number of HVLs