General Brachytherapy Flashcards
radium-226 decay process of ? isotope results in stable ? isotope?
part of decay process of Uranium-238 resulting in stable Pb-206
Ra/daughter equilibrium takes how long to reach?
30 days
uniform sources have same concentration of radioactivity through entire ?
length
Cs-137 decays ?% in 6 months
1%
Cs-137 used for what implants?
gyn
Pd-103 decays by ? to ?
by e- capture to Rh-103
P-32 t1/2
14.3 days
P-32 used for what implants
intravascular & peritoneum
Ir-192 decays ? % per day
1%
Au-198 decays by what to what
B- to Hg-198
I-125 emits what
pure gamma emitter
Sr-90 emits what
pure beta emitter
activity aka
- strength of source
- rate of decay
- # of nuclei decaying per sec
decay constant incr then activity ?
incr; directly prop
decay constant is the total # ? that decay per unit time
total # of atoms that decay per unit of time
t1/2 incr then overall activity ?
decr; inv prop; decay decr
average E is the avg value of ? from each isotope
all emitted photons from each isotope
specific activity is the activity per unit ? of radioactive material
mass
specific activity decr then activity per gram ?
decr; directly prop
Ci is ? dps
3.7 x 10^10 dis/sec
Bq is ? dps
1 dis/sec
fletcher suite applicator is made up of ?
- uterine tandem
- cervical colpostats (ovoids)
- capsules for uterine
heymans capsules are used when ? still intact
uterus
delclos is used for ? afterloading
uterine-vag
burnett applicator is use for tx of ?
tx vaginal tissues
Ra-226 dose distrib based on
calcs
square or rectangular implants aka
planar implant
multiple plane implants are spaced how far apart
1 cm apart & parallel
with volume implants, more than ? planes of sources are used
2
quimby/memorial system is similar to ?
paterson
quimby system uses what calc system
long & away
paris system is ? distribution like ?
UNIFORM distrib like quimby
trocars are what used for what implants
hollow needles used for interstitial implants
anisotropy results when source construction causes ? dose distribution
non-uniform
mean life is the ? lifetime for decay of isotope
avg lifetime
exposure rate constant aka
gamma factor
objectives for implant dosimetry is to determine distribution of sources & type to provide ? dose distribution
optimum
autoradiograph determines
uniformity
full strength needles have ? mg Ra/cm
0.66 mg Ra/cm or 0.5