CH.38-39 Flashcards
This is radiation received constantly from the earth, sun, stars, buildings and out own bodies.
Natural Background Radiation
What is the average cumulative dose per year of natural background radiation?
300mR
range- 100-500
What are the 3 main sources of natural background radiation?
- Cosmic- sun stars space
- Terrestrial- earth
- Internal- own bodies
What are the main sources of man-made radiation?
- Medical applications
- Consumer products
- Technology
- Waste
- Building Materials
The amount of radiation from cosmic sources are dependent on what?
elevation level- the higher the elevation the greater the cosmic mR
The amount of radiation from terrestrial sources are dependent upon what?
Mountain areas have higher dose levels
This is a natural by-product of transmutation in the decay of uranium.
Radon gas
Radon gas only exposes what type of tissue?
Lung tissue
What are some types of medical applications associated with radiation?
- Dental x-rays
- Diagnostic x-rays
- CT scans
- Nuclear medicine
- Radiation therapy
- Dexa
What is the average dose of radiation from medical applications?
55mR
This is narrowly defined as the intensity of radiation incident upon the surface of an object.
Exposure
Exposure is best detected as what?
Ionization events in the air just above the surface, which can generate electrical charge in a detecting device.
This is the intensity of radiation entering through the surface into the body, not the amount absorbed by the body.
Entrance Skin Exposure (ESE)
Which conventional unit is used only for x-rays, not for particulate radiations?
Roentgen R
One roentgen is equal to how many ion pairs in a cubic cm of air?
2.08*10^9 ion pairs in a cubic cm of air
This is the only appropriate unit for measuring the intensity of the “raw” x-ray beam emitted by the X-ray tube at a particular distance.
Roentgen
What does Rad stand for?
Radiation Absorbed Dose
What does Rem stand for?
Radiation Equivalent in Man
This is the unit for dose equivalent and true biological harm.
Rem
Roentgen measures what?
Exposure (surface) in ionizations in Air
Rad measures what?
Dose energy absorbed
Rem measures what?
Dose equivalent biological harm
The curie measures what?
Radioactivity in decays per second
1 Rad is equal to how much energy absorbed?
1r=100 ergs/gm of tissue
This is the relative harmfulness of radiation compared to 250 kV X-rays.
Wr
This is the relative sensitivity of the exposed tissue compared to other tissue.
Wt
Which type of tissue is the most radiosensitive?
lymphocytes
Which type of tissue is the most radiation resistant?
Nervous tissue
What are the weighting factors for X-rays, gamma rays, and beta particles?
1
What is the weighting factor for protons?
2
What is the weighting factor for alpha particles?
20
The weighting factor for neutrons is based on what?
the amount of energy
What is the tissue weighting factor for cortical bone and skin?
.01
What is the tissue weighting factor for organs in general?
,05