what is the unit for measurement of expsure to x and gamma radiation
roentgen
what does rem stand for
radiation equivalent man
fluorscopic entrance exposure rates are measured in _____
roentgen
what other device meausres radiation in air
pocket dosimeter (R)
we express exposure(X) as
what is the definition of this unit
roentgen
measurement of radiation in air
what is an ionization chamber used for
measure radiation exposure
what is the unit for absorbed dose
what is absorbed dose
RAD or GY
the amt of energy per unit mass absorbed by an irradiated object
what energy is responsible for any biological damge resulting from exposure
absorbed energy
how do reduce absorbed dose to patient
use high kvp and low mas
what technical affects absorption into the body
low kvp
the amoutn of absorption is is dependent on what three things
atomic # of tissue composing the structure
mass density of the tissue
energy of the incident photon
Absorption increases when:
atomic # ______
Mass density ______
Photon enrgy _____
increases
increases
decreases
what is radiolysis
when radiation splits a water molecule in the body
what is LET
linear energy transfer is the amt of ionizations per unit length of tissue
the majority of the energy is emitted with ____ of the maximum kv
1/3 or 30-40 percent
what absorbs more ionizing radiation bone or soft tissue
bone
rad to gy?
gy to RAD?
REM to Sv
Sv to REM
divide by 100
mult. by 100
divide by 100
mult. by 100
mill to no milli
no milli to milli
divide by 1000
mult. by 1000
Radiation with high LET transfers ______ amounts of energy to a ______ area
large
small
High LET has ____ penetration
low LET has _____ penetration
low penetration but more energy in a closed area
high penetration but less energy or ionizations per unit length
list examples of high LET and low LET
high LET = alpha and beta particles
low LET = x and gamma radiation
Dose equivalent or Equivalent dose, effective dose is measured in what unit
REM or Sv or Eqd
rem or Sv
what is dose equivalent
the product of the average absorbed dose in a tissue or organ and its associated radiation weighing factor (Wr) (type of radiation)
the Wr stand for what and is the same as what
Wr= weight of radiation (weight of beta alpha and gamma radiation)
sames a quality factor of particles
what are stochastic effects
non threshold, randome probability of occuring biological effects of ionizing radiation such as cancer & genetic abnormalties
what are non stochastic effects
these effects have a threshold you would need a certain amount of radiation (threshold) to get cataracts, hair loss or burns
what is the effective dose(EfD)
what two things does it incorporate
the sum of the weighted equivalent doses for all irradiated tissues or organs, it includes the type of radiation used(xray gamma neutron) and the variability in radiosensitivity of the specific organ or body part irradiated thru the use of proper weighting factors
what unit is the tissue weighing factor expressed as
what is the definition of this value
Wt
it is a vlue that denotes the % of the summed stochastic riscks (cancer+genetic)stemming from tissue irradiation
it accounts for the risks to the entire organism brought on by irradiation of individual tissues and organs
what is collective effective dose (ColEfd)
what is its SI unit
describes radiation exposure of a population or group from low doses of different sources of ionizing radiation
person-sievert
what is the formula for effective dose:
formula for equivalent dose:
formula for dose equivalent:
DxWrxWt
DxWr
DxQ (quality factor)
what does air kerma stand for (3 acronyms)
what is it
kinetic energy in matter
kinetic energy released in material
kinetic energy released per unit mass
an SI quantity that can be used for radiation concentration transferred to a point that maybe at the surface of a patients or radiographers body
coulomb per kilogram is the SI unit for what?
radiation in exposure in air
surface integral dose
total amount of radiant energy transferred by ionizing radiation to the body during radiation exposure
which dose involves the tissue weighting factor
effective dose
which dose involves the radiation weighting factor
equivalent dose
which does deals with the amoutn of radiation absorbed in an irradiated object per unit mass and is measured in rad or gy
absorbed dose
how is one rad expressed mathematically
1rad=100 erg/g
what is dap and what does it stand for
dose area product is the sum of air kerma over the exposed area of the patients body
what contains a known quantity of air with precisely measured temperature and humidity