Chapter 2 Radiation Types Sources Doses Flashcards
Dose from annual natural background radiation is approximately?
3.1 mSv
Annual dose from medical radiation is approximately?
2.3 mSv
Annual dose from human made radiation is approximately?
0.1 mSv
Annual dose from all natural, medical, human made radiation is approximately?
5.5 mSv
What are alpha particles?
Emitted from the nuclei of very heavy elements such as uranium and plutonium during radioactive decay
Contain 2 protons and 2 neutrons
Has a mass 4 times the mass of a hydrogen atom and a positive charge twice that of an electron (+2)
What are beta particles?
Identical to high speed electrons except for origin.
Are 8000 times lighter than alpha particles and have an electrical charge of (-1)
What is beta decay?
Occurs when a nucleus relieves instability by a neutron transforming itself into a combination of a proton and an energetic electron (beta particle).
What particle is able to penetrate biological matter to a much greater depth than alpha, with far less ionization along their paths?
Beta particles.
What is neutrino?
Has a negligible mass and no electric charge, but carries away any excess energy.
What is linear accelerator?
High speed (high energy) electrons are commonly produced in a radiation oncology treatment machine.
Use nonnuclear electrons that are most often used to treat superficial lesions in small areas or to deliver radiation boost treatments to breast tumors at tissue depths not exceeding 7 to 8 cm.
What are protons?
Positive charge, significantly less penetrating than high energy electrons.
What’s an isolated proton?
Identical to an ionized hydrogen atom, has a mass that exceeds the mass of an electron by a factor of 1800.
What’s a neutron?
Neutral charge and has same mass as a proton
What’s an isotope?
Two atoms that have the same number of protons, but different number of neutrons in their nuclei.
What’s a Radioisotope?
Is a combination of z protons and some of neutrons that leads to an unstable nucleus.
Z number?
Refers to the number of protons in the nucleus of an atom.
What’s absorbed dose?
The amount of energy per unit mass that has been absorbed into a material due to its interaction with ionizing radiation.
Measured in gray (Gy) or fractions of gray centigray (cGy)
What’s equivalent dose (EqD)?
Takes into account the type of ionizing radiation that was absorbed.
Provides an overall dose value that includes different degrees of tissue interaction that could be caused by different types of ionizing radiation
Measured in millisievert (mSv)
1 mSv is equal to how many sievert?
1/1000th
What’s effective dose (EfD)?
Best estimate of overall harm that might be produced by a given absorbed dose of radiation in human tissue.
Takes into account both the type of radiation and part of the body irradiated.
Measured in millisievert (mSv)
Biologic damage
Happens by ejecting electrons from the atoms composing the tissue, destructive radiation interaction at the atomic level results in molecular change, and this, in turn, causes molecular damage
What’s organic damage?
Changes in blood count that results from non negligible exposure to ionizing radiation
Whole body exposure of .25 mSv?
Effects: blood changes
Whole body exposure of 1.5 mSv?
Effects: nausea, diarrhea
Whole body exposure 2.0 mSv?
Effects: erythema (diffuse redness over skin)
Whole body exposure of 3 mSv?
Effects: if to gonads temporary infertility and 50% of death
Whole body exposure of 6.0 mSv?
Effects: Death
Three components of natural background radiation:
Terrestrial radiation
Cosmic radiation
Internal radiation
What’s terrestrial radiation definition?
From radioactive materials in the crust of the Earth.
What’s cosmic radiation definition?
From the sun (solar) and beyond the solar system (galactic)