28: Radiation Toxicity Flashcards
what is alpha decay
parent isotope losing 4 mass and 2 atomic number
2p+2n with double positive charge
alpha particle decay occurs only for radionuclides with Z
> 83
the alpha particle has a kinetic energy between ______ and is _____ for a particular radionuclide decay
between 4-8MeV
monoenergetic for a particular radionuclide decay
the biological hazard from alpha particles is due to their ________ kinetic energy and ___ positive charge
high
double
alpha particles are (select below)
1. large
2. small
3. penetrating
4. not very penetrating
5. easily absorbed
6. not very easily absorbed
1, 4, 5
what drug undergoes alpha decay (2)
XOFIGO (radium Ra 223 dichloride)
Bi-DOTATOC
what is the indication for XOFIGO
castration resistant prostate cancer
ZOFIGO MOA
alpha emitter, Ra mimics Ca, taken up into bone to target bone metastesis
XOFIGO’s _____, ____, and ________ minimizes toxicity
specificity, elimination, short half life
Bi-DOTATOC indication
neuroendocrine tumor liver metastases
_______ emitter drugs prevent normal cells getting caught in crossfire
alpha
beta particle decay is characteristic for ________ with ____________
unstable nuclides with excess of neutrons (neutron rich species)
in the beta particle decay process, the ______ spontaneously converts to a ______________ and _________. the _________ remains in the nucleus while the _______ is ejected
neutron
proton and beta particle
proton remains
beta particle ejected
the emitted particle in beta particle decay is identical to an
electron
how does A, Z, and N change in beta decay
A same
Z + 1
N-1
what drug undergoes beta decay (3)
iodine-131
lobenguane
lutetium-177
iodine-131 is used for
dx and tx of thyroid cancer, hyperthyroidism, thyroid carcinoma
lobenguane is used for
adrenal gland tumors
lutetium-177 targets
somatostatin receptors expressed on gastroenteropancreatic neuroendocrine tumors
positron decay emits a particle identical to ______ but _______
identical to electron but + charge
positron decay is characteristic for unstable radionuclides with ________
excess of protons in the nucleus (proton rich or neutron poor)
in positron decay, a _______ converts to a _____ and a _______ is ejected
proton converted to a neutron and a positron (+ beta particle) is ejected
how do A, Z, N change in positron decay
A same
Z-1
N+1
what is the primary decay mechanism of technetium radiopharmaceuticals
isomeric transition
the excited state of radionuclides is called __________ and is indicated by a _______
metastable
superscripted m
when metastable states go to ground state, they release of energy in the form of a _____
gamma ray
what is the decay process where metastable states release energy in the form of gamma rays to go down to ground state
isomeric transition
the metastable species _____ is an important medical imaging radionuclide which decays by isomeric transition
99-mTc
T or F: 99-mTc can be built into many molecules to allow for imaging different organs
T
alpha particles cause _____ of targets and produces ________
ionization
ion pair
which of the following is true about beta particles
1. they have the same energy as gamma rays]
2. they do not travel in a straight line
3. they travel further than alpha particles
4. they cause an antimatter + matter reaction
5. all of the above are true
6. 2, 3, 4 are true
6
Antimatter/mater rxn explanation:
B+ particle –> rxn takes placein pET imaging. B+ interacts with e-, annihilate each other and release E which produces GAMMA RAYS (why PET imaging can be used, cuz you’re looking at gamma rays).
positrons from internally targeted radioactive drugs are detected via ________ by specialized cameras to give 3D pet images
their gamma rays
_______ are very penetrating = main reason that lead and other dense shielding is used where radiopharmaceuticals are prepared or used
photons - gamma rays
_____ emission can occur during decay modes
photon
photons are _____energetic
mono
_______ and _________ have the same character as light, UV, and IR radiation but have higher energies
gamma rays and x rays
gamma rays are ___ path length, ____ specific ionization
long
low
radiocontrast media + xrays =
- What is radiocontrast media?
positive contrast media
attenuate X rays more than body tissues
iodinated copounds
- radiocontrast media: is when you get molecuels of the target tisseu to absorb the radiation so can image.
the higher a relative osmolality of iodinated contrast media =
higher the toxicity
what osmolality of iodinated contrast media is best for lowest toxicity
iso
nonionic dimers are _____ but _________
less toxic but more expensive
ADRs of iodinated contrast agents
non-IgE allergic rxns (but behaves like AN ANAPHYLACTIC RxN - biggest risk is previous exposure and rxn like an IgE mediated allergic rxn) occur more with higher osmolality iodine containing compounds
rate is much lower with lower osmolality
biggest risk of an ADR from iodinated contrast agents is
previous exposure and reaction
radiation safety can be assessed by determining factors such as
exposure and dose
the newer unit of an absorbed dose is
the gray (Gy)
1Gy = __ joule/ kilogram = ___ rad
1 joule/ kilo = 100 rad
T or F; the # of Gy reflects the actual damage caused by radiation
F- the different types of radiation have different capacity to cause damage even thought he energy absorbed is the same
relative hazard of radiation is related to ________ and ________
specific ionization (ion pairs produced per unit path length) and linear energy transfer (LET)
- What is the unit we use to measure the damaging effects of a radioactive molecule on humans?
1 Sv =?
- what is the Weighting Ratio of gamma rays and beta particles?
- what abouyt for alpha partilces?
- use the Sievert (Sv). Sievert unit= IMP MORE IN pop/public/Occupational health.
1 Sv= 1Gy x WR
- 1, 20.
MOST times, the WR is just 1.
the relative damaging potential of radioactive emissions is defined by ____ or _____
quality factor (Q) or weighing factor (WR)
the radiation equivalent dose is measured by
sieverts
list 3 cells that are highly radiosensitive
mature lymphocytes
erythroblasts
some spermatogonia
(rapidly dividng cells)
list 3 cells that are highly radioresistant
fibrocytes, chondrocytes, muscle cells, nerve cells (slowly dividing cells)
the brain spinal chord could be considered _______radiosensitive
low
high doses of radiation acuses
acute radiation sickness
AEs from lower doses of radiation =
cancer (leukemia), shortened life span
1Gy = 1 ________
joule absorbed energy/ Kg
2-7Gy sees
hematopoietic sx, damage of bone marrow, infections as main issue
7-15 Gy sees
Gi sx, death after 5-10 days , GI mucosa destroyed
50 Gy sees
CNS sx, death in minutes to 48h, due to neurologic and CV degeneration
survivors rare rare at doses over ___Gy
5`
all survivors increased risk of leukemia
cancer latent period usually <15yrs
what is considered the LD50 of radiation in humans?
5Gy
list 3 sx of radiation sickness sx
N/V/D, HA, fever, dizziness and disorientation, weakness and fatigue, hair loss, bloody vomit and stools from internal bleeding, infections, low BP
list the 4 tx for radiation sickness
G-CSF (filgrastim)- bone marrow
blood transfusion
KI- outcompete radioactive I
metal chelators (prussian blue, DTPA)
