rad bio chapter 18 /crb

consist of 2 protons and 2 neutrons and are therefore simply helium nuclei

what are emitted from unstable heavy nuclei such as radium or radon during the decay process

because of their charge and heavy mass, what travel only short distances (can be stopped by a sheet of paper)

what produce intense ionization and are therefore high linerar energy transfer (High LET) radiation

what are extremely hazardous if ingested or inhaled but are less dangerous if the exposure is external (have greater biologic effect)

what is High LET

electrons emitted by the nucleus

may be negatively charged (negatron) or postively charged

negatively charged

positively charged

not stable and may exist for only very short periods of time

emitted and accompanied by a small massless, chargeless particle known as the neutrino

small massless, chargeless particle

which particles have the same rest mass as an electron and are usually emitted frome the nucleus with high velocities

what may be used for shielding, but bremsstrahlung radiation may result

bremsstrahlun x-ray production is _____ proportional to the square of the _____ ____ of the absorber

bremsstrahlung x-ray production is ____ proportional to  the square of the mass of the _____ particle

Thus, ____ _____ is much more likely to occur with beta particles then with alpha particles

bremsstrahlung radiation is much more likely to occur with ____ particles, than with ____ particles

rays both forms of electromagnetic radiation

electromagnetic radiation

have no mass and no charge

photons emitted from a nucleus

extranuclear and result from rearrangements within the electron shells or from bremsstrahlung radiation

gamma rays are emitted from

x-rays are within

except for their origins, there is no difference between ____ and ____

the most common types of ionizing radiation used in radiation therapy

radiation with sufficient energy to separate an electron from its atom

alpha particles:
charge number
atomic mass
origin

beta particles (negatron):
charge number
atomic mass
origin

beta particles (positron):
charge number
atomic mass
origin

Neutrinos:
charge number
atomic mass
origin

x-rays:
charge number
atomic mass
origin

gamma rays:
charge number
atomic mass
origin

% for radon

% for cosmic

% for terrestrial

% for internal

% for medical x-rays

% for nuclear medicine

estimated % of all radiation exposure of the u.s. population comes from natural background sources

estimated 82% of all radiation exposure of the u.s. population comes from ___ ___ ___ 

3 sources of natural background radiation

rays that bombard the earth

radiation that emanates from radioactive materials naturally occurring in the earth

deposits of radionuclides in our bodies

originate from nuclear reactions in space or from our own sun

____ ____ interact with molecules in the atmosphere to create other reactive agents known as ____ particles

with cosmic rays, exposure is ____ at the polar regions than at the equator

with cosmic rays latitude, solar cycles and other factors may account for a variation of ___ % in exposure

earth is made up of hundreds of materials, many of which are naturally radioactive

terrestrial radiation are naturally radioactive because of teh presence of small amounts of  long-lived isotopes of ____, ____, and ____.

the largest exposure to terrestrial radiation involves

may be particularly harmful because it is an easily inhaled gas

what is EPA

estimates that radon exposure is the second leading cause of lung cancer in the u.s.

results from the radioactive materials that are normally present in our bodies

the amount of ionization produced by photons in air per unit mass of air

traditional unit for exposure is

the energy absorbed per unit mass of any material

1 Gy=100cGy=100 rad

takes into account the fact that different types of radiation produce different amounts of biologic damage

example of dose equivalent ____ ____ and ____ are high-LET radiation and therefore have a greater biologic effect than x-rays

takes into account the effect of irradiation of only part of the body or the effect of nonuniform irradiation of the body

the rate at which the radioactive isotope undergoes nuclear decay

traditional unit of activity is

3.7 x 10¹⁰ disintegrations per second

the SI unit is ____ which is 1 disintegration per second in activity

traditional unit for exposure

traditional unit for absorded dose

traditional unit for dose equivalent

traditional unit for activity

quality factor (QF) for x-rays and gamma rays

quailty factor (QF) for fast neutrons and alpha particles

this instrument has a chamber filled with gas that is ionized in part of whole when radiation is present

either the total quanity of electrical charge is measured or the rate at which charge is produced is measured

two kinds of gas-filled detectors may be found in a rad therapy dept

consist of two electrodes within a gas-filled chamber, an applied voltage across the electrodes & electronics

a meter to amplify and measure the electrical signal

because of the sensitivity, they are best for finding contamination and other low levels of radiation

when ____ ____ are properly calibrated, their accuracy approaches ___%, which makes them suitable for measurement of the radiation output of therapy equipment.

what is TLDs

because of their small size, they are widely used to measure radiation in a number of applications

as the name implies, thermoluminescent, materials give off light when ____.

the ____ number of LiF is close to that of tissue

if proper care is taken, ____ can be measured with and accuracy of approx ___%.

also used for mailed intercomparison of therapy unit calibration

ring badges unsed for personnel monitoring & for measurements of environmental levels of radiation

after development, x-ray film exposed to radiation turns ____

on x-rays the amount of blackness is called

related to the amount of radiation received by the film

has a slot in which the film (in its protective paper cover) may be placed and serveral thin metal filters that surround portions of the film

filter allow discrimination between different types and energies of radiation

______ radiation will not penetrate any of the filters but can reach the film in the area where no filters are present.

primary task is to analyze the existing data related to radiation exposure

to assess the radiobiologic risks associated with those exposures

these agencies can develop recommendations for dose limits

the role is to license users of radioactive materials and radiation-producing equipment

inspect such users, and enforce the appropriate laws

one of the leading federal regulatory agencies in the u.s. is the

oversees the use of isotopes produced in nuclear reactors.

isotopes are commonly used in ____ ____ departments, in _____ and as sources for teletherapy (external beam radiation) and _____ (internal implants)

with regulatory agencies, many states have entered into agreements concerning licensing, inspection and enforcement with ___ and have become "agreement" states.

as part of the agreement, states must maintain a certain level of _____ with NRC regulations

transportation of radioactive material is primarily the concern of _____ and the NRC

the use of machines that produce ionizing radiation, such as x-ray units and linear accelerators, fall under the jurisdiction of the ____________ and state agencies

the EPA and _______ also have regulations that relate to the use of radiation.

we have a far greater knowledge of the effects of ____ doses of radiation than those of _____ doses.

in sufficiently high quantities, radiation can be

a single whole-body exposure of approx ___ cGy is lethal for ___% of the exposed population within ____ days of this event. Termed LD50/30

even at levels below the lethal dose, there are significant long-term effects related to exposure to radiation. 2 general classifications

are those for which a threshold exists and for which the severity of the effect increases with dose

are those that have no threshold and for which the probabilty of occurance is a function of doses.

the severity of the effect is not a function of the dose

the regulatory requirements for limits for exposure to radiation for various groups, and practical methods for individual radiation protection

contribute to the annual dose to individuals

a form of ionization chamber, this is used for personnel monitoring

examples of nonstochastic effects are:

threshold doses for these effects are relatively high, which is reflected in the higher permitted doses tothe specific organs involved.

*note*

what is ALARA

the less radiation received, the lower the risk

practical radiation protection from the external beam radiation should include the time-honored methods of

rate of nuclear decay

the source of ionizing radiation that contributes the most to exposure of the general population in the u.s. is

which type of device is best suited for output measurements of radiation therapy equipment

stochastic, or nonthreshold, effects of radiation exposure include:

exposure of which of group of people would contribute the most to the genetically significant dose

the annual effective doe equivalent limit for radiation works is

G-M detector is 2 m form a small brachytherapy source and measure rate of 10 mR/hr. what exposure rate would you expect to measure if the detector were moved to 4 m from the source

energy absorbed per unit mass

ionizing per unit mass of air by photons

short range, relatively heavy-mass, high-LET particle