Radiation Detectors Flashcards
standard free air ionization chamber is ? measuring device
Roentgen measuring device
thimble ion chamber & stem capacitor made up of ?
air cavity w/Al rod in center
condenser chamber brand
victoreen R
stem effect occurs when
- ioniz occurs @ the stem rather than pt of measurement
- innacurate
baldwin farmer chamber kind
thimble ion chamber
extrapolation chamber measures
surface dose
pancake chamber what kind
parallel plate
pocket ioniz chamber used for ? periods
used for short periods
cutie pie size
portable
proportional counters more sensitive than
ion chamber
geiger mueller used to measure
sealed/unsealed low gamma rays & unsealed beta
ion recombination region ? voltage
low voltage
ion chamber region/ionization saturation point voltage
300V
in proportional counter region neg ions get enough E to cause
more add’l e- to be liberated
if add voltage in Geiger counter region
no effect
kerma stands for
kinetic E released in matter
f-med or f-factor relates dose in air to
dose in tissue
f-med depends on (3)
- E of photon beam
- material/medium (type of absorber)
- mass E absorption of the coef of absorber
bragg-cavity theory used to determine
absorbed dose from ioniz chamber reading
bragg cavity smaller than range of
e-
chemical dosimetry uses
fricke or ferrous sulfate=ferrous sulfate, sodium chloride, sulfuric acid
TLD is solid ?
state
OSL stands for
optical stimulating luminescence
calorimetry measures in form of
heat based on temp chg
silicon dosimetry type
n-type & p-type
dose equivalent units
- SI unit= Sv
- traditional= rem
film badges price
cheap, inexpensive
Ngas
cavity-gas calibration factor introduced by the TG21 protocol for dose determination
degree of blackening is related to
optical density
possible leakage from package surface rate exceeds
6600 dpm
scintillation counter most sensitive for detection of
gamma ray
air kerma measured by
R, expressed in Gy
calibrate chambers temp/pressure
- 22degC
- 760 mm Hg
ionization type survey meter reads amount of ? in room
scatter
finger badge given if receive greater than ? annual effective dose equivalent limit
10%
penetrometer designed by
Benoist
chromoradiometer designed by
Holzknecht
methods of dose determiniation (3)
- ion chamber
- tld
- film
film made of
transparent base coated w/emulsion w/silver bromide crystals
dose rates w/o phantom measured with
buildup cap of a thickness equal to depth of dmax
dose rate in tissue measured where
cax @ ssd @ dmax
standard free air ionization chamber measures in ?
air
standard free air ionization chamber only for ? instruments
secondary
standard free air ionization chamber used where?
not used in department
standard free air ionization chamber made up of
lead box with 2 parallel plates
thimble ion chamber & stem capacitor for ? Z
low
thimble ion chamber & stem capacitor composed up
thin wall (plexiglass, plastic)
thimble ion chamber & stem capacitor uses buildup cap for?
high E & TAR
thimble ion chamber & stem capacitor does not use build up cap for?
low E, TMR/TPR
condenser chamber kind
thimble ion chamber
condenser chamber connected to ?
condenser
condenser chamber used with ? E
low
condenser chamber shows ? effect
stem
baldwin farmer chamber connected to
electrometer for instant readout
baldwin farmer chamber used with ? E
high
baldwin farmer chamber reduces stem effect ? %
< 1%
pancake chamber has ? spaced 2 mm apart
electrodes
pancake chamber measures what depth
superficial
pancake chamber useful in circumstances where ?
cylindrical chambers cannot be used
pocket ioniz chamber needs to be
zeroed out
pocket ioniz chamber can give false reading because of
leakage
pocket ioniz chamber requires how freq attn?
daily & recordings
pocket ioniz chamber is how sensitive
most sensitive personnel measuring device
proportional counters discriminate b/n
alpha & beta
proportional counters used to measure in
radioactive spills
geiger mueller filled with
gas
geiger mueller detects
lost sources
geiger mueller used to survey
room, personnel, instruments, implants
geiger mueller disadvantage
can have dead time
ion chamber region/ionization saturation point is region
where ionization chamber should fxn
in proportional counter region causes
over read
cutie pie use for surveying
area for exposure, testing console
kerma is E per unit mass transferred from
photon to charged particles
f-med or f-factor is what conversion
R to rad
f-med or f-factor relates E released in matter to
E absorbed in matter
f-med or f-factor for water is
0.971
f-med or f-factor only for what kind of E beam
monoenergetic
f-med or f-factor not defined beyone ? MeV
3
f-med or f-factor ? must exist
equilibrium
bragg-cavity theory filled with
gas
bragg-cavity theory measured using
water phantom
bragg-cavity theory phantom made of
polysterene, plexiglass, parafin, solid water
bragg-cavity absorbing material greater than
range of e- equilibrium
bragg-cavity absorbing material must be
homogenous
bragg-cavity beam must be
homogenous
TLD made of
LiF
TLD measured how
heated & emitted light measured
TLD dose related to
light given off
TLD can be used how many times?
reusable
size of TLD
small
TLD is equivalent to
tissue
OSL measures what kind of radiation
x-ray, gamma, beta
OSL similar to
TLD
OSL uses
laser lights
OSL made of
aluminum oxide
OSL cost
less expensive
OSL can be used how many times
reusable
OSL how long for reading
instant
silicon dosimetry sensitivity
more sensitive than gas
silicon dosimetry- how long for reading
instantly
film badges how long reading lasts
permanent recording
film badges accurate within
10 mrem
film badges filters
detect different E levels
film badges provide info concerning
beam quality
penetrometer measures
quality of x-rays; kVp
Ngas depends on ? of walls
composition
Ngas depends on ? of chamber
volume
film darkening is related to
absorbed dose
