Radiation Protection

Question 1

Equivalent Dose

Answer 1

• measured in grays (Gy)

- biological effect of radiation type R with weighting factor Wr

Question 2

Deterministic effects

Answer 2

• have a threshold

- cataracts, fibrosis, organ atrophy

Question 3

Thermoluminescent (TLD)

Answer 3

• device containing small lithium fluoride chips functioning as sensing agents
• energized electrons are excited and get trapped in the crystaline lattice
• when read, release visible light-light proportional to dose received
• not affected by environment
• higher cost
• Recalibration required after each reading
• can be reused

Question 4

Effective Dose

Answer 4

• measured in sieverts (Sv)

- biological effect on tissue types. T having a weighting factor Wt

Question 5

RBE

Answer 5

Relative biological effectiveness

-the comparison of radiation with different LETs abilities to produce the same biological effect

Question 6

Law of Bergonie and Tribondeau

Answer 6

The radiosensitivity of a cell is a function of the metabolic state of the cell
-the more mature and specialized and cell’s function is, the less radiosensitive it is (ones that reproduce less rapidly)

Question 7

Pocket Ionization Chambers

Answer 7

• most sensitive
• self-reading and non-self-reading
• when exposed the air surrounding the central electrode ionizes the discharges the dosimeter in direct proportion to the exposure
• needs a special unit to charge and zero unit
• can discharge over time
• must be read and zeroed everyday

Question 8

What is radiation?

Answer 8

The transfer of kinetic energy that passes from one location to another

Question 9

Annual maximum permissible dose for a radiation worker vs. student

Answer 9

Worker: 20mSv
Student: 1mSv

Question 10

Cerebrovascular Syndrome

Answer 10

• 50Sv
• damage to and failure of CNS
• nausea, vomiting, cranial edema, meningitis

Question 11

Stages of ARS

Answer 11

• Prodromal: occurs within hours after exposure-nausea, vomiting
• Latent: lasts about a week, no symptoms
• Manifest illness: signs and symptoms of hematopoietic, gastrointestinal, and cerebrovascular syndromes start to show
• Recovery or death

Question 12

Effective dose equation

Answer 12

EfD = D x Wr x Wt

Absorbed dose x Wr = EqD
EqD x Wt = EfD

Question 13

Who discovered X Rays and when

Answer 13

1895, Wilhelm Roentgen

Question 14

Hormesis

Answer 14

The theory that small doses of radiation can benefit you

Question 15

Cardinal Rules of X Ray

Answer 15

Time
Distance
Shielding

Question 16

Types of Radiation

Answer 16

Natural: terrestrial, cosmic, internal

Mad-made: diagnostic imaging, research, etc.

Question 17

Body’s defenses against free radicals

Answer 17

• Antioxidants-vitamins A, C, E can all donate and electron to the radical to neutralize it
• Enzymes: naturally target free radicals

Question 18

LET

Answer 18

Linear energy transfer

-the energy transferred from ionizing radiation to a medium as it passes through per unit length

Question 19

Electromagnetic Wave Equation

Answer 19

C=f(wavelength)

Question 20

3 ways free radicals can harm

Answer 20

• Cell membrane disruption
• Reactions with proteins/enzymes: affect their functions
• Reactions with DNA: most dangerous-mutations occur

Question 21

Stochastic Effects

Answer 21

• dont have a threshold

- cancer effects, genetic effects, birth defects

Question 22

Gastrointestinal Syndrome

Answer 22

• 6-10Sv
• damage to epithelial cells of GI tract
• nausea, vomiting, infection, anemia, fluid loss

Question 23

Optically Stimulated Luminescence (OSL)

Answer 23

• thin layer of aluminum oxide-read using a laser light
• luminesces in proportion to radiation eposure
• worn up to 1yr
• more sensitive than TLD
• filter packs (aluminum, tin, copper) cause different degree of attenuation of radiation hitting the detector
• recalibrated after each reading, ideal for pregnant workers and low radiation areas

Question 24

Speed of light

Answer 24

3x10^8

Question 25

Absorbed Dose

Answer 25

Measurement of energy transferred from ionizing radiation per unit mass of irradiated material Measure in: Rads (r) Gray (Gy)

Question 26

Protraction vs. Fractionation

Answer 26

Protraction: a specific radiation dose given continually, but slowly Fractionation: same dose rate given in equal fractions or parts

Question 27

Types of Personnel Dosimeters

Answer 27

Film Badges Thermoluminescent Dosimeter Optically Stimulated Luminescence Pocket ionization chambers

Question 28

X Ray interactions with matter

Answer 28

``` Photoelectric absorption Compton Scatter Coherent Scatter Photodisintegration Pair Production ```

Question 29

Wave equation

Answer 29

V=f(wavelength)

Question 30

Interactions at the Anode Target

Answer 30

Bremsstrahlung Radiation | Characteristic Radiation

Question 31

Properties of X Rays

Answer 31

- Invisible - No mass - Travel in a vacuum - Travel in a straight line - Can penetrate the human body - Can be absorbed or scattered - ployenergetic , heterogenous - Can cause chemical and biological damage - Can cause chemical changes to occur in radiographic and photographic film - Electrically neutral - Cannot be optically focused - Produced in a range of energies - Can produce secondary radiation - Can cause things to fluoresce

Question 32

Target Theory

Answer 32

If the master molecule of a cell in damaged by radiation, the cell will die

Question 33

Occupational Exposure

Answer 33

Measured in: rem Sieverts

Question 34

Exposure in Air

Answer 34

A measure of the ionization of air produced by x rays and gamma rays Measured in: Roentgen (R) C/kg coulombs/kilogram

Question 35

OER

Answer 35

Oxygen enhancement ratio -radiation dose required to produce biological response without O2/radiation dose required to produce biological response with O2

Question 36

Who needs dosimeters?

Answer 36

Any person occupationally exposed to ionization regularly Workers who may be at risk of receiving 1/20th or more of the maximum permissible dose Any workers who may receive 1% of the EfD (0.05mSv) in any one month

Question 37

Hematopoietic Syndrome

Answer 37

- 1-10Sv | - decrease in blood cells, platelet numbers, and bone marrow stem cell numbers

Question 38

Film badges

Answer 38

- records whole body exposure at a low rate for long periods of time - records densities by the filters on the film - film is permanent record - sensitive to extreme temp and humidity-can become fogged

Question 39

Pair Production Energy Range

Answer 39

1.022 MeV +

Question 40

Photodisintegration Energy Range

Answer 40

10MeV +

Question 41

Photoelectric Absorption Energy Range

Answer 41

As long as the incident photon energy is higher than the binding energy of the electron

Question 42

Compton Scatter Energy Range

Answer 42

50keV

Question 43

Coherent Scatter Energy Range

Answer 43

Less then 10keV

Question 44

``` Atomic numbers: Lung Muscle Bone Fat ```

Answer 44

Lung: 7.4 Muscle: 7.4 Bone: 13.8 Fat: 6.3

Question 45

Differential Absorption

Answer 45

The difference in absorption of x rays by different body tissues

Question 46

Absorption + Scatter

Answer 46

Attenuation

Question 47

When does the photoelectric effect increase?

Answer 47

- low kVp - high atomic # - increased thickness of matter - increased density of matter

Question 48

What impact does photoelectric effect have on radiography?

Answer 48

- increased contrast | - increased patient dose

Question 49

2 factors that determine the energy of a Compton interaction

Answer 49

- angle of deflection | - energy of incident photon

Question 50

ARS

Answer 50

Acute radiation syndrome: an illness caused by whole body exposure of high doses of radiation