Radiation 1 Flashcards
define radiobiology
the study of the action of ionizing radiation on living things
What are three reasons we need to take images?
- illness
- injury
- Screening
define efficacy
the ability to produce a desired or intended result
What is the responsibility of the referring physician?
makes the determination that an x-ray exam is necessary (weighs risk vs benefit)
What is the responsibility of the radiographer?
Takes optimal images using minimum amount of radiation exposure in order to reveal the presence or absence of a disease or injury
What is the responsibility of the radiologist?
in addition to viewing images and making a diagnosis from them, a radiologist may also be involved in directly using medical radiation equipment, such as fluoroscopic units (makes decisions to alter what imaging examination is appropriate if necessary
What does ALARA stand for?
As Low As Reasonably Achievable
What does ORP stand for?
Optimization for Radiation Protection
What are the three cardinal rules of radiation protection?
- Time
- Distance
- Shielding
What are the two main risks of irradiation?
- radiogenic cancer
- genetic defect
What does BERT stand for?
Background
Equivalent
Radiation
Time
What does BERT explain?
It gives a mean for comparison. Emphasizes that radiation is a part of our environment. Easy for patient to understand
What is the alliance for radiation safety in pediatric imaging?
to increase awareness of the need to reduce radiation dose for pediatric patients
Define radiation
is ENERGY in the form of high-speed particles or waves. (energy in motion)
What are the two types of radiation?
- non-ionizing
- Ionizing
what is the speed of light?
3 x 10^8 m/s
what is the smallest quantity of this electromagnetic energy?
photon
Do photons has a mass and an electrical charge?
no
what are photon energy measured in?
electron volts (eV)
define electromagnetic spectrum?
a continuum of various levels/types of radiation.
As one moves from left to right on the spectrum, the amount of energy increases
define ionization
addition or removal of an electron from atom
what are examples of non-ionizing radaition?
visible light, infrared, microwaves, and radio waves
What is ionizing radiation produced by?
unstable atoms
What are the two types of ionizing radiation?
- particulate
- Electromagnetic
What are the three particulate ionizing radiation?
- alpha particles
- Beta particles
- Neutrons
What are the electromagnetic ionizing radiation?
- Gamma rays
- X-rays
define nuclear fission?
when a neutron collides with the nucleus of an uranium atom, the atom splits which releases more neutrons.
what are the two types of electromagnetic radiation?
- gamma rays
- x-rays
How are x-rays produced?
when fast moving electrons collide with atoms of metallic elements
-x-radiation also has a very short and it has high penetrating power
define LET
is the energy transferred per unit length of track
what are the two radiation categories for LET?
Low-linear
High-linear
what are 2 examples of low-LET?
-x-rays, gamma rays
What are 2 examples of High-LET?
-alpha particle, neutrons
What are the two radiations that humans are exposed to?
- Natural
- Manmade
What are the three natural radiations?
- terrestrial
- Cosmic
- Internal
What is terrestrial radiation?
from radioactive materials in the crust of the earth
What is cosmic radiation?
from the sun and beyond the solar system
What is internal radiation?
from radioactive atoms that make up a small percentage of the bodys tissue
What are some examples of man-made radiation?
- air travel
- Medical radiation
- nuclear energy
- consumer products
What are the two interactions with matter?
- photoelectric absorption
- Compton scattering
define radiobiology?
is the study of the action of ionizing radiation on living things
the damage that occurs varies based on a number of different factors including:
- type of cells
- energy and type of radiation
- Metabolic rate
- amount of radiation
- Age and sex of patient
- area/amount of tissue exposed
what are the 8 sequence of events leading up to human body damage from radiation?
- absorption of x-rays by atom
- Ionization/excitation of atom
- Chemical bond break
- Molecular damage
- Cell damage
- Tissue damage
- Organ/system damage
- Human body damage
What are the two effects of radiation?
somatic or genetic
define somatic effects?
when an individual has been exposed to ionizing radiation and sustains biological damage
define genetic effects
when an individual genetic material has been irradiated and there is genetic malformation in their offspring
what are the two different radiation interactions?
- Indirect
- direct
define radiolysis
when the absorption of radiation occurs in a water molecule, free radicals are produced, which cause biological damage
(the dissociation or separation of water molecules due to ionization cause by radiation
which is most of our body? direct or indirect?
indirect. 2/3 of effects on tissues
what are 5 direct interactions that may cause damage?
- single strand
- double strand
- double strand in same rung
- mutation
- covalent cross links
what does OH* + OH* form?
hydrogen peroxide (H2O2)
what does H* + O2* form?
a hydroperoxyl radical
what are the 4 organic molecules?
carbohydrates, lipids, proteins, nucleic acids
what is the master molecule?
DNA
what damage does LOW-let do to DNA?
single-strand break.
what damage does high-LET do to DNA?
double-stand break, same rung
what are the 4 consequences to the cell from structural changes within the nucleus?
- restitution
- Deletion
- Broken-end rearrangement with visible damage
- Broken-end rearrangement without visible damage
What is the target theory?
states that when cell DNA is directly or indirectly inactivated by exposure to radiation, the cell will die
the number of cells that survive a radiation exposure are _____ proportional to the dose to which it was exposed
directly
