Nuclear Medicine Board Review 5.0 Study Guide 2024

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