Lesson 5: Review of Ionizing Radiation Flashcards
What is natural radiation
Always present in the environment
What is manmade radiation
Created by humans for a specific purpose
What sources contribute to total radiation a person recieves in their lifetime
Natural and manmade
3 sources of natural radiation
Terresterial Radiation (Radon) from decay of the earths soil, water, vegetation
Cosmic Radiation: typically gamma and beta radiation from stars
Internal radiation: ingestion inhalation (ingesting uranium that breaks down into radon internally)
5 Sources of manmade radiation
Air travel
Nuclear fuel/power generation
Atmospheric fallout from nuclear weapons
Nuclear powerplant accidence
medical radiation
Where does radon gas in a home come from
Penetrates from the soil up into the home from cracks in the framework
What are the 2 largest sources of artificial radiation
Diagnostic imaging (CT, fluoro, radiography)
what is BERT
Background Equivalent Radiation Time
emphasizes the radaiation that is apart of our innate environment
ie: chest xray is like 10 days of natural radiation
2 categories of radiation
electromagnetic and particulate
What is particulate radiation
- alpha, beta particles neurons and protons
subatomic particles that are ejected from atoms at high speeds
cause ionization at direct atomic collision
Alpha particles
emitted from very heavy elements such as uranium and plutonium during radioactive decay
they are helium nuclei minus their electrons
large mass and positive charge
ability of alpha partciles to penetrate matter
alpha particles are less penetrating than beta particles
considered harmless externally and damaging internally
Beta particles
identical to electrons except theyre emitted from the nucleus of a radioactive atom
capable of penetrating to a greter depth than alpha particles
how many types of x-rays do we produce
2
- bremmstrahlung and characteristic
What is radiation exposure
Radiation travelling through air
What is radiation dose
Radiation travelling through a medium
unit of exposure examples
SI unit – Coulomb per kilogram (C/kg)
Conventional Unit - Roentgen (R) or milliroentgen (mR)
Conversion: 1R = 2.58 x 10-4 C/kg
Why bother with a unit that deals with radiation traveling through air?
Eff Z of Air = 7.8, Eff Z of muscle = 7.6, Eff Z of H2O = 7.5
attenuation processes for air, soft tissue, and H2O is very similar,
meaning that a number of dosimetric experiments and measurements can take place quite easily in air to represent what might be happening in the human body.
What is air kerma
How much energy is deposited from xrays to air
- total kinetic energy released in a unit mass of air
- J/kg
- kerma and absorbed dose are the same thing at diagnostic level
What is dose area product
An estimation of the total amount of energy delivered to a patient (at the entrance surface) during an exposure
Sum of the total Air Kerma over the exposed surface area of the patient.
Expressed using Gycm2 or mGycm2
What is absorbed dose
Absorbed dose measures the amount of energy that is imparted to a medium
It is defined as the mean energy deposited to a medium by ionizing radiation divided by the mass of that medium
Equivalent dose
Equal absorbed doses of different types of radiation produce different amounts of biologic damage in body tissue.
the absorbed dose in Gy in a tissue/organ and its radiation weighting factor
What is radiation weighting factor
Radiation Weighting Factor (WR) is a dimensionless factor (a multiplier) used for radiation protection purposes to account for differences in biologic impact among various types of ionizing radiation
EqD=
EqD= D x WR
What is effective dose
- tissue weighted sum of the equivalent doses in all specified tissues and organs
- includes the effect of the type od radiation and the radiosensitivity of the organ
EfD=
EfD= D x WR x Wt
Tissue Weighting Factor
takes into account the carcinogenic sensitivity of each organ
3 examples of excessive occupational dose diseases
- radiodermatitis
-cancer - blood disorders
Early Effects of Radiation
Nausea,fatigue, diffuse redness of the skin, loss of hair
