Card Set Information
Radiation with sufficient energy to seperate an electron from its atom
What are the 2 major groups of radiation sources?
External Beam therapy machines
Which source of radiation use gamma rays, x-rays, and sometimes electrons
such as cobalt teletherapy units or linear accelerators
What source od radiation use gamma rays & x-rays from sources such as cesium-137, iridium-192, and iodine-125.
Consist of 2 protons and 2 neutrons and therefore are simply helium neclei
They are emitted from unstable heavy nuclei such as radium or radon during the decay process
Can only travel short distances.
--most can be stopped by a sheet of paper, but they produce intense ionization and are therefore high linear energy transfer (LET) radiation
They are extremely hazardous if ingested or inhaled but are less dangerous if the exposure is external
Electrons emitted by nucleus
They may be either negatively or positively charged
Negatively charged beta particles are called
positively charged beta particles are called
_______ are not stable and may exist for only very short periods of time
Whenever beta particles are emitted, they are accompanied by a small, massless, chargeless particles known as the
metals may be used for shielding, but ____ radiation may result
The probability of bremsstrahlung x-ray production is ___
___ to the square of the atomic number of the absorber and ___ ___ to the square of the mass of the incident particle
Bremsstrahlung radiation is much more likely to occur with ____ particles than with ____ particles
____ & ____ are both forms of electromagnetic radiation (photons)
x-rays & gamma rays
____ have no mass and no charge
____ are photons emitted froma nucleus
_____ are extranuclear and result from rearrangements
within the electron shells or from bremsstrahlung radiation
Except for their origin, there is no difference between ___ and ____.
xrays & gamma rays
xrays, gamma rays, and electrons are the most common types of ionizing radiations
It is estimated that ___% of the radiation exposure of the United States population comes from natural background sources
What are the amounts of radiation exposure for
man made ____%
What are the 3 sources of natural background radiation?
The primary cosmic rays interact with molecules in the atmosphere to create reactive agents known as _____.
Whhat natural radiation originates from nuclear reations in spce or from our own sun
Exposure is _____ at the polar regions than at the equator
Latitude, solar cycels, and other factors may account for a variation of ___% in exposure.
The intensity varies even more with increasing elevation
What natural source is made up of small amounts of long lived isotopes of uranium, thorium, and radium among others
The ___ ___ ___ estimates that radon exposure is the 2nd leading cause of lung cancer in the U.S. (following smoking)
Enviromental Protection Agency
___ ___ results from the radioactive material that are normally in our bodies
What are examples of man-made sources?
xrays - nuclear medicine procedures, TV, tobacco products, nuclear reactors, fuel cycle, & fallout from above ground nuclear weapons testing
___ is defined as the amount of ionization produced by photons in AIR per unit mass of air
___ ___ is defined as the energy absorbed per unit mass of any material
___ Gy = ___ cGy = ___ rad
___ ___ takes into account the fact that different types of radiation produce different amounts of biologic damage
Alpha particle & neutrons are __ ___ LET radiation and therefore have a greater biologic efect than x-rays
To account for differences in biologic response, each type of radiation is assigned a quality factor
What is the traditional unit of:
The QF of
xrays & gamma rays=
___ ____ ___ takes into account the effect of irradation of only part of the body or the effect of non uniform irradation of the body
effective dose equivelent
The units for the effective dose equivelent are also the Sievert & the REM
___ is the rate at which a radiaoactive isotope undergoes nuclear decay
The traditional unt of activity is the curie (CI)
This SI unit is the becquerrel
What are the 2 kinds of gas-filled detectors that may be found in a RT dept.
** When ionization chambers re properly calibrated their accuracy approaches ___% which makes them suitable for measurement of the radiaiton output of therapy equipment
What form of ionization chamber is used for personal monitoring
the pocket dosimeter
becuase ionization chambers are not very sensitive, they are not suitable for the detection of very low levels of radiation or radiation contamination
Because of their sensitivity, G-M detectors are best for finding contamination and other low levels of radiation
Because of their small size, ___ ___ are widely used to measure radiation in a number of applications
TLD's thermoluminscent dosimeters
Thermoluminscent materials give offlight when heated
The atomic number of LIF is close to that of tissue
With proper care, doses can be measured with an accuracy of approximately ___ %
**After development, x-ray film exposed to radiation turns black.
This amount of blackness is called the ___ ___
The optical denisty is the amount of radiation received by the film
The primary task of ___ ___ is to analyze the existing data related to radiation exposure and to access the radiobiologic risk associated with those exposures
It is the role of the ___ ___ to license users of radioactive materials & radiaiton-producing equipment, inspect such users, and enforce the laws
many states have entered into agreements concerning licensing, inspection and enforcement with the NRC have become ___ states
effects have no threshold and for which the probability of occurance is a function of dose
ex: cancer induction, genectic effects and embryologic & teratogenic effects
___ effects are those for which a threshold exist and for which the severity of the effect increases with dose
: erythema (skin reddness),
epilation (hair loss)
What are the significant long term effects related to exposure to radaition?
nonstochaltic & stochastic effects
WHat does the LD 50/30 means?
lethal dose or 50% of the population in 30 days
we have a far greater knowledge of the effects of high doses than those of low doses.
In sufficiency high quanitites, radiation can be lethal. A single whole body dose of 4.5 ___ is lethal for ___5 of the exposed population with in ___ days of the event
what agency oversees the use of isotopes produced in nuclear reactors.
These isotopes are currently used in nuclear med dept, labs as sources for teletherapy & brachytherapy
nuclear regulatory commission
TLD's are also used for mail intercomparision of therapy units calibration, in ring badges used for personal monitoring, and for measurements of enviromental levels of radiation.
A typical ___ ___ has a slot in which the film may be placed and several thin, metal, filters that surround portions of the film.