extra stuff on rad safety Flashcards
three cardinal rules
- time
- distance
- shielding: only for technologist
there won’t be pt shielding the on ARRT
3 types of exposure
- occupational : exposure from work
- medical exposure: exposure during diagnostic procedures
- public exposure : natural radiation
2 target interactions
- brems
- characteristic
HAPPEN IN TUBE
-straight line in
justification mean
there must be a benefit associated with and procedure or exposure
optimization
all exposures are kept as low as reasonably achievable- ALARA
dose limitation
established dose limits
ex.) occuptational whole body 50 mSv
what is the K shell binding energy of tungsten?
69.5 or 70 keV
-meaning we at least need 70 kvp to kick it out!
quality
kvp determines quality
- the higher the kvp, the higher the quality of the beam
quantity
refers to the number of x-ray photons
-higher mA, higher number of photons
-higher the mA, higher patient exposure
if you increase energy, and increase frequency what happens to wavelength
wavelength decreases
-because it gets shorter!
inverse square law
the inverse square law states that the intensity of radiation is inversely proportional to the square of the distance between the x-ray tube and the image receptor
when distance is double, intensity is __________by 4 x
decreased
when distance is cut in half, intensity is _________ by 4 x
increased
matter interactions
occur at patient
-all start with an x ray photon ( wave in)
photoelectric effect or absorption
-photon in
-total absorption of the x ray election
-inner shell electron knocked out of orbit
-the ejected photon is termed a “ photoelectron”
photoelectric effect is the main source of what radiation
radiation dose to the patient
compton scatter
- photon in
-outer shell electron - only one that has 2
compton effects what source of exposure
occupational exposure
which is us
coherent
-occurs at low levels
-no absorption
- doesn’t happen to use
- has a lot of diff names
compton sees the most
fog!
the higher the atomic number the ______the attenuation
greater
alpha particle
is the heaviest type of radiation particle
beta particle
cosmic radiation in the atmosphere and exits all around us. emits beta radiation
neutron
doesn’t have any charge and is present in the nucleus of an atom
electromagnetic radiation
x rays and gamma rays
NCRP chart # 160
-natural sources of radiation: 3 mSv
-medical imaging 3.2 mSv(ct is the largest dose)
-,chart addresses radiation exposure from all sources to people living in the US
Air kerma
measures the ENERGY of ionization in air
exposure
NUMBER of ionizations in air
if the As have greys
absorbed dose
air kerma
weighting factor of 1
x ray
beta
gamma
weighting factor for alpha
20
effective dose
expresses in siverts
-multiples 3 things
-tissue weighting factor risk of cancer
equivalent dose
in sieverts
-radiation weighting factor
exposure units
coulomb/ kg
air kerma
greys
absorbed dose
greys
the law of bergonie snd tribondeau states
the radiosensitivty of a cell is directly proportional to reproductive rate and is inversely proportional to its degree of differentiation
mitosis phase
is very sensitive
lymphocytes
are the most radiosensitive blood cells
small intestine is more radio sensitive then
the large intestine
reproductive cells
are very sensitive
-unspecialized
most resistant
least resistant
-
DNA
- adenine (A) & Thymine (T)
-cytosine (C) & Guainen(G) - be able to match them **
charctersitc
- k shell inner shell!!
scatter comes from the
patient
air kerma units
Greys
air pollution, big clouds of grey!
1 Gy= ____ joule/kilogram
1
absorbed dose
energy absorbed in matter per into mass
-grey
equivalent dose
multiple the absorbed dose by a radiation weighting factor
-units in siverts
Equivalent dose
if there’s a letter q you’re going to multiply by two! 
effective dose
takes the greys radiation weighting fat or AND a tissue weighting factor
-accounts for the fact that some tissues are more radiosensitive( at greater risk of cancer)
Sv= Gy x Wr x Wt
if there is a T multiplied by three 
effective dose
exposure
Number of ionizations in air 
air kerma
Energy of ionizations and air 
ICRP
international commission on radiologic protection
Conducts research and provides recommendations on radiation protection WORLDWIDE *
NCRP
National Council on radiation protection in measurements
Publishes scientific research recommendations on radiation protection in measurements in the U.S*
