Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/89

Click to flip

89 Cards in this Set

  • Front
  • Back
the radiological unit of activity is
Curis (Ci)
the SI units for Ci (Curie) are
Becquerel (Bq)
the radiological unit of exposure is
Roentgen (R)
the radilogical unit of absorbed dose is
rad
the SI unit for rad is
Gray (Gy)
rem =
radiation absorbed dose (rad) x Quality Factor (QF) or biological effect factor (RBE)
600 rad lethal toatol body radiation represents how many calories
100
the energy required per ionization in air is
34 eV
the energy required per ionization in water is
100 eV
the measure of energy deposition by a radiation per unit of track is
linear energy transfer (LET)

units: KeV/mum
alteration of a target molecule by direct absorption of energy is called
direct action
alteration of a target molecule by a chemical reaction w/ a product of the radiolysis of a neighboring moleducle (such as a free radical) is called
indirect action
a species having an unpaired valence electron
free radical
the radiolysis of water results in the production of
H and OH free radicals as well as hydrated e-
a radical which is a mjor oxidizing species when there is not oxygen present
OH

when oxygen is present there is HO2 and H2O2 present which are more aggresive oxygenating agents
when oxygen is present a pressure greater than what - cells are more radiosensitive
5 to 10 mm
some tumor cells are hypoxic and more radioactive resistant
what might you use colorny forming units (CFU) for
in vitro to make precise dose-response curves
the inverse of the slope of the exponential region of a dose response curve
extrapolation numbers (n)
RBE is defined as
dose of a standard radiation (250 KeV xrays) required to obtain a given biological effect / the dose of the test radiation required to produce the same biological damage endpoint
LET increases as particle energy?
charge on particle?
velocity of particle
LET increases as particle energy decrease, charge increases, velocity decreases
as LET increases, RBE
increases, until levels of LET are reached where deposited energy is wasted as over kill.
RBE increases as dose
decreases

in other words the higher the RBE - the lower the dose needs to be to get a given effect
visible abnormalities that occur when radiation occurs on cells undergoing interphase
swelling, pyknosis of nucleus
the most importan reversible block or division delay produced by radiaiton appreas during what stage in the cell cycle
G2
why does fractionation and protraction of the radiation dose result in less cellular damage
sublethal and potentially lethal radiation damage is repairable in a time-dependent fashion
non-ionizing and cause the formation of pyrimidine dimers
UV light
disease associated with a repair deficiency
xeroderma pgimentosum (XP)
the principle cell renewel systems involved in radiation sickness are the
hemopoietic and gastrointestinal systems
lethal doses for mammalial populations of radation are close to (in rads)
450 rads
skin changes to radiation may be characterized by
erythema, dry desquamination, moist desquamination, necrosis
delayed necrosis is due to
damage to the fine vasculature and CT
Law of Bergoinie and Tribondeae broadly states that
radiosensitivity varies directly with the rate of proliferation or mitotic activity and with the number of future divisions the cells with undergo, and inversely with the degree of morphologic and functional differentiation
ALARA
keeping doses as low as reasonalby achievable
the incidence of malignancy increases as the dose increases upt to 300 rads, and then
incidence rate reduces

result of cell killing at higher doses
this relationship is the working hypothesis on which recommendations for radiation protection are base
simple linear dose-response curve
two mechanisms that may explain radiation-induced cancer1.
1. somatic mutaiont
2. makes cellular environment mroe compatible for viral-induced or chemical malignant transformation
X-rays induce high incidence of what kind of mutaitons
point
the mutation doubling dose for humans is approx

measured in rems
60 rems
in the testis and female what are the most sensitive cells
spermatogonia

granulos cells in growing follicles
a dose of what may be harmful to the human fetus
in rads
5 to 10 rads
in addition to carcinogenesis, the late effects of radiation included (4 things)
aplastic anemia
lifespan shortening
cataracts
retinal dysplasia
how does radiation affect eh immunity response of mammals
suppresses it
represent the larges man-made source of radiation exposure
medical diagnosit x-rays
the gonadal dose that, if received by every member of the population would be expected to produce the same total genetic effect on the population as the sum of the individual dose actually received is called the
genetically significant dose (GSD)
deposited in the environment, can be concentrated at various stages i the food chain, used in therapy, etc... (e.g what causes radiation)
radionuclides
reside in lungs or in bones of many man may produce very high internal doses since all of the energy of the particles emitted will be depositid w/in organ of localization
alpha particle emitters
acute radiation syndrome
when the whole body or a major part of it is exposed to a large acute dose of penetrating radiation
three stages of acute radiation syndrome
1. Prodromal phase (1-2 days)
2. Latent period (days-wks)
3. manifest illness
at high doses - CNS is involved
if the prodromal phase which includes nausea, vomiting, anorexi, etc occured w/in two hours then dose is probably
more than 200 rem
a dose of what might lead prodromal phase to lead directly to manifest illness (w/o latent period)
600 rem -
epilation (loosing hair) occurs at what rem
350 for some
700 for all
pancytopenia
lymphocyte counts fall w/in first day or two w/ max depression after 200 rem
a lymphocyte count of 1200 over 48 hours suggest
less serious exposure
what does a neutraphil count near zero by the 4th or 5th day suggest
poor prognosis and irrepairable damage
platelet counts parallel neutrophils
what heralds recovery of blood production
return of reticulocytes into circulation
a marrow mitotic index of zero on the 4h day may mean a dose in excess of (in rem)
200 rem
diarrhea occurs how soon after exposure
about 4 days
if the dose is in the order of thousands of rems and CNS is involved what is the most likely outcome
death w/in hours
mortality reaches 50% at what rem and 100% at what rem
50 at 400 and
100% at 600 rem
if the prodromal symptoms are still present on the third and fourth days, the dose is most likely
400-600
hospitilization should be carried out where the exposure dose is suspected of having been what or more (rems)
100 rem
treatment of prodromal symptoms should be prompt and may consist of
sedatives and antimetics
changes in the blood picture will be developing in spite of the absense
symptoms
type of particle stopped by a sheet of paper, does not penetrate skin. consists of a neutron and two proteons.
alpha

problem arises when material gets inside body by inhalation, ingestions etc
stopped by a layer of clothing or less than an inch of sustance
B

electron ejected from the nucleus of a radioactive atom. may causes skin injury if exposed for a long time. protective clothing as precaution
travel many feet in air and many inches in human tissue - "penetrating" radiation
Gamma rays and x-rays

(photons)
gamma and x radiation frequently accompanies the emission of beta and alpha radiation
how does alpha, beta, and gamma differ in their LET
alpha - high LET
beta and Gamma - low LET
which particle is more potent and causes more tissue damage
alpha

only 5 rad of alpha particles produced the same effect (in rem) as 100 rad of gamma and beta particles
absorbed dose weighted by type of radiation
rem
to calculate rem you are multiplying rad by a radiation weighting factor - the radiation factor for x-rays, gamma rays, and beta particles is
1

QF might be higher for other types of radiation
about how much is the annual natural background radiation
200mrem annually
physical half life
time required for the activity of a radioactive material to decrease by one half due to radioactive decay
biological half life
time required for the body to eliminate half of the radioactive material (depends on chemical form)
the net effect of the combination of the physicial and biological half-lives in removing the radioactive material from body
effective half life
metal which insulates radioactive material
lead
in a case w/ a pt who has been exposed - what comes first decontamination or patient stabilit?
pt stability
the latent period (interval) is affected how by dose
decreased latent period w/ increased dose
a dose over 3,000 will cause damage to the
CNS

vomitting, diarrhea, confusion, severe hypotensiont w/in minutes. collapse of cardiovascular and CNS - fatal 24 to 72 hours
what is the effect on skin after less than 100 rem
no visible injuries

at over 500 = erythema, epilation
over 1,800 = desquamation
1 Sy =
a "doubling dose" = (1Gy)
percentage change in risk for given dose (relative change rate)
excess relative risk (EER)
LD50/30
about 450 rads - death for mammals usually
EER and EAR can vary w/
age at exposure, gender, attained aga, etc..

EER is excess relative risk which is the percentage change in the risk for a given dose

EAR is the absolute change in rates for a given dose
what is the effect for doses less than the threshold on a dose response curve re cancer
none -
how does ERR change as you get older
decreases with age at exposure and age
EAR is affected by age how
EAR increases w/ age

age specific excess rates decrease with age at exposure
life saving actions guidance (NCRP-116) in mrem
50,000
pts are said to be contaminated when
radioactive material is on their skin or in their bodies. radiation safety precautions are not needed for patients who have only been exposed and are not contaminated
placing the radioactive source in a lead container is a type of
shielding