Nuclear Medicine Board Review 5.0 Questions and
Answers
what are survey meters used to measure?
radiation exposure rates
what type of survey meter is used for surveys to detect contamination?
Geiger-Muller (GM) counter
The NRC requires that a nuc med facility have a survey meter capable of
detecting exposure rates between what range? and what instrument
accomplishes this?
0.1 mRem/hr and 100 mRem/hr
GM
what two things can be fitted at the end of a GM counter
end window probe and pancake probe
what doe a pancake probe do?
allows tech to survey larger area
what does an end window probe do?
must be pointed directly at source for accurate detection (used in survey at dearborn to
detect the radioactive lymph node)
a GM counter is not as accurate as _____________-
proportional ionization meters "cutie pies"
why is a "cutie pie" better than a GM couner?
it can measure high dose rates
what is the main use of a proportional ionization chamber "cutie pie"?
determining the exposure rate being produced by a patient who has received a
therapeutic dose of a radionuclide
what does a well counter use to detect radiation?
thallium activate sodium iodide (NaI[TI])
can detect very small activity levels
why is a well counter more efficient than a gamma camera if they both use NaI
crystals to detect radiation?
because the sample is actually placed inside the well
what occurs when too many photons strike the crystal in the well counter (above
2 uCi)?
the instrument can go into dead time (paralysis) and fail to document incoming counts
from the source
, what are well counters primary used for?
wipe tests to measure very low levels of removable radiation
true/false: well counters cannot detect levels below background levels seen on a
GM counter
false- it can detect levels below background seen on the GM
besides wipe testing, what else are well counters used for?
counting blood, plasma, and samples from patients who are having non-imaging studies
such as blood volume and Schilling test
what type of crystal is used in an uptake probe?
NaI crystal
what is an uptake probe used for?
to find the amount of activity within a patient
why is the uptake probe not as sensitive as a well counter?
because the detector-to-source geometry
what is the limit of a flat-field collimator (uptake probe)?
limits the area seen by the crystal and eliminates much of the background activity
why must a patient be placed several inches from the end of the uptake probe?
to ensure the entire organ of interest is within the field of view
what is an uptake probe commonly used for?
thyroid uptake studies
what would occur if the patient is too close to the uptake probe or if the area of
interest is too large?
counts will be lost because some of the photons being emitted will miss the opening of
the collimator
a dose calibrator is what?
an ionization chamber
what does a dose calibrator measure in (unit)?
curie or becquerels rather than cpm
what type of photons do dose calibrators more frequently pick up over others?
gamma photons over Beta (B) radiation because only high energy B radiation can pass
through the glass chamber walls
what is the benefit of using SPECT imaging over planar?
SPECT provides greater sensitivity and resolution in imaging deep tissue or when there
are other interfering tissues
what is the benefit of SPECT imaging from many angles?
exact location and size can be better determined for tumors and pathologies
why is patient to detector distance a problem with SPECT imaging?
the camera may be very close to the patient at some projections and far away at others
why are PET crystals denser and thicker than gamma camera crystals?
to stop the 511 keV photons produced during annihilation
systematic errors are ____________ but _____________________-
Answers
what are survey meters used to measure?
radiation exposure rates
what type of survey meter is used for surveys to detect contamination?
Geiger-Muller (GM) counter
The NRC requires that a nuc med facility have a survey meter capable of
detecting exposure rates between what range? and what instrument
accomplishes this?
0.1 mRem/hr and 100 mRem/hr
GM
what two things can be fitted at the end of a GM counter
end window probe and pancake probe
what doe a pancake probe do?
allows tech to survey larger area
what does an end window probe do?
must be pointed directly at source for accurate detection (used in survey at dearborn to
detect the radioactive lymph node)
a GM counter is not as accurate as _____________-
proportional ionization meters "cutie pies"
why is a "cutie pie" better than a GM couner?
it can measure high dose rates
what is the main use of a proportional ionization chamber "cutie pie"?
determining the exposure rate being produced by a patient who has received a
therapeutic dose of a radionuclide
what does a well counter use to detect radiation?
thallium activate sodium iodide (NaI[TI])
can detect very small activity levels
why is a well counter more efficient than a gamma camera if they both use NaI
crystals to detect radiation?
because the sample is actually placed inside the well
what occurs when too many photons strike the crystal in the well counter (above
2 uCi)?
the instrument can go into dead time (paralysis) and fail to document incoming counts
from the source
, what are well counters primary used for?
wipe tests to measure very low levels of removable radiation
true/false: well counters cannot detect levels below background levels seen on a
GM counter
false- it can detect levels below background seen on the GM
besides wipe testing, what else are well counters used for?
counting blood, plasma, and samples from patients who are having non-imaging studies
such as blood volume and Schilling test
what type of crystal is used in an uptake probe?
NaI crystal
what is an uptake probe used for?
to find the amount of activity within a patient
why is the uptake probe not as sensitive as a well counter?
because the detector-to-source geometry
what is the limit of a flat-field collimator (uptake probe)?
limits the area seen by the crystal and eliminates much of the background activity
why must a patient be placed several inches from the end of the uptake probe?
to ensure the entire organ of interest is within the field of view
what is an uptake probe commonly used for?
thyroid uptake studies
what would occur if the patient is too close to the uptake probe or if the area of
interest is too large?
counts will be lost because some of the photons being emitted will miss the opening of
the collimator
a dose calibrator is what?
an ionization chamber
what does a dose calibrator measure in (unit)?
curie or becquerels rather than cpm
what type of photons do dose calibrators more frequently pick up over others?
gamma photons over Beta (B) radiation because only high energy B radiation can pass
through the glass chamber walls
what is the benefit of using SPECT imaging over planar?
SPECT provides greater sensitivity and resolution in imaging deep tissue or when there
are other interfering tissues
what is the benefit of SPECT imaging from many angles?
exact location and size can be better determined for tumors and pathologies
why is patient to detector distance a problem with SPECT imaging?
the camera may be very close to the patient at some projections and far away at others
why are PET crystals denser and thicker than gamma camera crystals?
to stop the 511 keV photons produced during annihilation
systematic errors are ____________ but _____________________-
