Radiation Biology and Safety

Question 1

Radiation

Answer 1

Is energy that travels through space and matter

Cannot be seen. felt, smelled, tasted, or heard

Question 2

Electromagnetic Radiation

Answer 2

Waveform energy having no mass

Ionizing and nonionizing

x-rays, gamma rays, UV light

Photon: discrete energy packet of EM radiation

Question 3

Particulalte Radiation

Answer 3

has mass and energy

Disintegration of an unstable atom

all types are ionizing

alpha and beta particles, neutrons

Question 4

Ionizing Radiation

Answer 4

radiation with adequate energy to ionize atoms and molecures

Question 5

Ionizing Radiation:

What does it do?

Answer 5

produces free electrons

creates unstable atoms

Produces scattered low energy x-ray photons

Creates free radicals

Damages cells/DNA

Question 6

Radiation Facts

Answer 6

Radiation is around us all the time. It is as much a part of our everyday environment as the light and heat of the sun’s rays. Scientists call this background radiation and measure it in units called millirems

Question 7

Sources fo Ionizing Radiation

Answer 7

Natural radiation

1. Cosmic Rays from the sun
   
   1. greatest at high elevations
2. Terrestrial Radiation from earth’s crust
   
   1. radon accounts for majority of natural radiation
3. Internal form radionuclides in body
   
   1. potassium-40

Question 8

Sources of Ionizing Radiation:

Man-made 50%

Answer 8

Enhanced naturally occurring sources

Tobacco, building materials, mining and agriculture activities, combustible fuels

Artificial sources

medical radiation

x-rays, CT, Nuclear medicine

Question 9

Biologic Effects:

Target Theory

Answer 9

key molecule – most often DNA

Cell death may result if a key molecule is damaged by ionizing radiation

Cell’s reproductibe ability may be damaged/lost

Question 10

Law of Bergonie and Tribondeau

Answer 10

Radiosensitivity of cells is directly proportional to reproductive activity and inversely proportional to degree of differenetiation

The most radiosensitive cells are:

not mature, specialized, or differentiated

Highly reproductive

Have long mitotic phases

Question 11

Effects of exposure on embryo/fetus

Answer 11

Perimplantation = death

organogeneiss = malformation

Effects decreases with development

Question 12

Stochastic effects

Answer 12

Random mutations >>>>> transformations

carcinogenic

teratogenic

Probability of occurrence increases with radiation dose, but severity of disease does not

No dose Threshold – chance is always there

Question 13

Non-stochastic Effects

Answer 13

Result in individual cell death

Directly related to the dose received

Minimum threshold does must be surpassed

Side effects of radiation therapy

Question 14

Acute Radiation Syndrome

Answer 14

Acute illness caused by ionizing radiation

Occurs when:

large penetrating dose

external source

dose received by majority of body

Dose delivered in a short time

Question 15

Maxiumum Permissible Dose

Answer 15

National council on radiation protection and measurements

Dose allowed in a specific period of time

Dose set at which no adverse effects have been noted

Question 16

Regulations

Answer 16

• Exposure for pregnancy should be less tahn 500mRem for entire pregnancy and less than 50mRem per month
• To be considered under the pregnant worker policy a woman must declare her pregnancy in writing
• Minors - no exposure allowed
• General public - 1/10 of occupational whole body dose

Question 17

ALARA

Answer 17

As low as reasonably achievable

Always minimize radiation dose when possible

MPDs are guidelines only

Any amount of radiation can be harmful