November 8, 1895
what was the date when x-rays was discovered
Wihelm Conrad Roentgen
who is the german physics professor discovered xrays
light emanating from a piece of paper coated with barium platinocyanide
What did Wihelm observed when he experiment ended
somatic damage
biologic damage to the body of the exposed individual caused by exposure to ionizing radiation
1896
somatic damage was reported in Europe as early as____
Clarence Madison Dally
who became the first american radiation fatality
occupational exposure
radiation exposure received by radiation workers in the course of exercising their professional responsibilities
radiodermatitis
many radiologists and dentists developed a reddening of the skin, skin lesions on the hands and fingers
British X-ray and radium protection committee
in 1921 a group was form to perform guidelines for the manufacture and use of radium and xray equipment and devices to eliminate the chance of occupational injury
not agree on workable unit of radiation exposure
The committee could_____so the committee failed on their responsibility
skin erythema dose
as the received quantity of radiation that causes diffuse redness over an area of skin after irradiation
reliable unit
scientist felt compelled to continue searching for a ____.
International Commission on Radiation Units and Measurements
was a formed in 1925,
1928
what date was the Second International congress of radiology was held in Sweden and "roentgen" was accepted but not adequately defined
early deterministic somatic effects
which appeared within minutes, hours, days, or weeks of the time of radiation exposure examples nausea, fatigue, diffuse redness of the skin, and loss of hair, intestinal disorders, fever, and blood disorders,shedding of the outer layer of skin
late deterministic somatic effects
effects of ionizing radiation examples are cataract formation, fibrosis, organ atrophy, and loss of parenchymal cells, reduced fertility, sterility
late stochastic effects
which type of effects of ionizing radiation are cancer, genetic (hereditary) effects
tolerance dose
is a radiation dose to which occupationally exposed persons could be continuously subjected without any apparent harmful acute effects such as erythema. Currently not used for radiation safety
threshold dose
a dose of radiation lower than which an individual has a negligible chance of sustaining specific biologic damage. Currently not used for radiation safety
1934, 0.2 roentgen
the International X-ray and Radium Protection commission recommended a tolerance dose daily limit of what and the year?
1936, 0.1 roentgen
____ the committee reduced this dose to _____ per day
Maximum permissible dose (MPD)
by the early 1950s: replaced the tolerance dose for radiation protection purposes and the largest dose of ionizing radiation that an occupationally exposed person was permitted and that was not anticipated to result in major adverse biologic effects as a
tolerance dose
what was no longer accepted as a means for protecting radiation workers from the acute effects of ionizing radiation and meant that no amount of radiation was safe
the solution was to compare rates of death and accident among various occupations
What was the solution for the dilemma how much dose of radiation in the work environment a worker can get?
insurance
What type of companies has been using this method of comparison for many years to determine rates?
deep sea diving, professional mountaineering
Examples of occupation very hazardous:
trade, government desk work
Examples of occupation nonhazardous:
dosimetry, risk
By the 1970s,____ and ____ analysis had become quite sophisticated.
alpha, beta, gamma, x-radiation, neutrons
Radiation units were developed that contained factors that accounted for the varied bioeffects of different types of radiation:
late 1970's
what decade was when dose limits were calcuated and established to ensure that the risk from radiation exposure acquired on the job did not exceed risks encounter in "safe
10^-4 per year= 1 out of 10,000
what is the risk for clerical worker to get exposure of radiation
1991
what year was when ICRP revised tissue weighting factors
effective dose
(EfD) based on the energy deposited in biologic tissue by ionizing radiation
the type of radiation, variable sensitivity of the tissues exposed to radiation
EfD accounts two things:
sieverts (Sv)
EfD is expressed which are SI units or in millisieverts (mSv), subunits
roentgen (R)
one time the internationally accepted unit for the measurement of exposure to x-radiation and gamma radiation
1 Sv
___ is = to 100 rem
1 roentgen
is the photon exposure that under standard conditions of pressure and temperature produces a total positive or negative ion charge of 2.58 x 10^-4 coulombus per kilogram of dry air
Rem
stands for "radiation equivalent man" meaning the dose that is equivalent to any type of ionizing radiation that produces the same biologic effects as 1 rad of radiation
gray (Gy)
named after the English radiobiologist Louis Harold Gray and the SI unit of absorbed does of radiation.
Rolf Maximilian Sievert
Swedish physicist for whom the SI unit of equivalent dose was named and best known for his Sievert intergral
exposure
air kerma
absorbed dose
equivalent dose
effective dose
Diagnostic imaging professionals need to understand the following basic radiation quantities:
exposure (X)
as the total electrical charge of one sign, either all pluses or all minuses, per unit mass the x-ray and gamma ray photons with energies up to 3 million electron volts generate in dry air at standard temp. and pressure
practical
Such an instrument, however, is not a _____ device at locations other than a standardization laboratory.
coulomb (C)
is the basic unit of electrical charge
coulombs per kilogram (C/kg)
the exposure unit is measure in
2.58 x 10-4 C/kg of dry air
the roentgen was precisely defined as the photon exposure, the under standard conditions of pressure and temperature, produces a total positive or negative ion charge of
1/2.58 x 10-4 or 3.88 x 10^3
1 C/kg = ___ R or ___ R
air kerma
SI quantity that can used to express radiation concentration transferred to a point, which may be at the surface of a patient's or radiographer's body
tissue kerma
as the kinetic energy released in a unit mass of tissue
Absorbed Dose (D)
as the amount of energy per unit mass absorbed by an irradiated object
dose area product (DAP)
sum total of air kerma over the exposed area of the patient's surface
Zeff
effective atomic number of a given biologic tissue is a composite or weighted average, of many chemical elements
Bone
higher effective atomic number and Zeff # 13.8
Soft tissue
Zeff # 7.4
Calcium
Zeff # 20
phosphorus
Zeff # 15
Fat
Zeff # 5.9
Therapeutic Radiology
specified in terms of absorbed dose rather than in terms of exposure
1 J/kg
1 Gy =
100 erg/g
1 rad =
1/100 J/kg=1/100 Gy
1 rad =
Rad
stands for radiation absorbed dose
Surface integral dose (SID)
total amount of radiant energy transferred by ionizing radiation to the body during a radiation exposure. exposure area product is also what it is called too
linear energy transfer (LET)
helps explain the need for a quality, or modifying, factor and the amount of energy transferred on average by incident radiation to an object per unit length of track through the object
Equivalent dose (EqD)
the product of the average absorbed dose in a tissue or organ in the human body
radiation weighting factor (Wr)
chosen for the type and energy of the radiation in question
equivalent dose (EQD)
is used for radiation protection purposes when a person receives exposure from various types of ionizing radiation
tissue weighting factor (Wt)
weighting factor that takes into account the relative detriment to each specific organ and tissue
collective effective dose (ColEfD)
describe radiation exposure of a population or group from low doses of different sources of ionizing radiation
total effective dose equivalent (TEDE)
is radiation dosimetry quantity that was defined by the NRC
Nuclear Regulatory Commission
to monitor and control human exposure to ionizing radiation
committed effective dose equivalent
- is a measure of the probabilistic health effect on a individual who has ingested radioactive material into the body, is is the same effactive risk as the same about of equivilant dose applied to the whole body.
TEDE regulatory limit is ______ for the general public
.05 SV - .001 SV