CNMT flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Effective half-life formula
- 1/Te = 1/Tp + 1/Tb, where Tp is physical half-life and Tb is biologic half-life. The effective half-life is always shorter than either component.
- Tc-99m physical half-life
- Tc-99m decays by isomeric transition with a 6.02-hour physical half-life and emits a 140 keV gamma ray used for imaging.
- Mo-99 breakthrough limit
- The allowable Mo-99 concentration in Tc-99m eluate is 0.15 kBq Mo-99 per MBq Tc-99m (0.15 µCi/mCi), tested after each elution.
- Aluminum breakthrough limit
- Aluminum ion concentration in generator eluate must not exceed 10 µg/mL, tested by a colorimetric method.
- Hounsfield unit formula
- CT number = 1000 × (µtissue − µwater) / µwater. Water is 0 HU and air is approximately −1000 HU.
- Window width and level
- Window width sets the range of CT numbers displayed as gray, controlling contrast. Window level sets the center value, controlling brightness.
- CT pitch definition
- Pitch equals table travel per gantry rotation divided by beam collimation width. Pitch greater than 1 reduces dose and increases image noise.
- DLP and effective dose
- Dose-length product equals CTDIvol multiplied by scan length. Effective dose is estimated by multiplying DLP by a body-region conversion factor.
- CTDIvol meaning
- CTDIvol is the volume computed tomography dose index, a standardized dose metric measured in phantoms that accounts for pitch.
- Tc-99m sestamibi uptake
- Sestamibi is a lipophilic cation taken up by myocardial mitochondria in proportion to regional blood flow at the time of injection.
- Regadenoson contraindication
- Regadenoson is a vasodilator that should not be given to patients with severe asthma or high-grade atrioventricular block.
- Caffeine before vasodilator stress
- Caffeine and methylxanthines block adenosine receptors and must be withheld before regadenoson or dipyridamole stress, typically for at least 12 hours.
- Reversible perfusion defect
- A reversible defect shows decreased tracer uptake on stress images with normal or near-normal uptake on rest images, indicating ischemia.
- Fixed perfusion defect
- A fixed defect shows decreased uptake on both stress and rest images, suggesting scar or attenuation artifact rather than ischemia.
- Gated SPECT ejection fraction
- Gated SPECT calculates ejection fraction from end-diastolic and end-systolic volumes derived from ECG-gated frames across the cardiac cycle.
- Aminophylline reversal
- Aminophylline is used to reverse the effects of dipyridamole or regadenoson when severe symptoms occur during pharmacologic stress testing.
- F-18 physical half-life
- F-18 has a 109.8-minute physical half-life and decays by positron emission, producing annihilation photons for PET imaging.
- Annihilation photon energy
- Positron-electron annihilation produces two 511 keV photons emitted approximately 180 degrees apart, which are detected in coincidence.
- SUV formula
- Standardized uptake value equals activity concentration divided by injected dose divided by body weight. SUVmax is the most commonly reported metric.
- FDG patient preparation
- Patients fast for at least 4-6 hours before FDG PET, with glucose ideally below 200 mg/dL, and avoid vigorous exercise for 24 hours.
- FDG uptake time
- FDG PET imaging is typically performed about 60 minutes after injection, allowing uptake in tissues and clearance from blood.
- Brown fat FDG uptake
- Brown adipose tissue shows symmetric supraclavicular and neck uptake that is cold-related; warming and beta-blockade reduce this uptake.
- Time-of-flight PET
- Time-of-flight PET measures small differences in photon arrival times to localize annihilation events along the line of response, improving signal-to-noise.
- Rb-82 half-life
- Rubidium-82 has a 76-second half-life and is produced by a strontium-82/rubidium-82 generator for myocardial perfusion PET.
- NMAA scope of practice
- The nuclear medicine advance associate performs tasks within the scope defined by state law and institutional policy under supervision of a licensed technologist or physician.
- Two patient identifiers
- Before any dose administration or imaging procedure, staff verify two identifiers such as name and date of birth to confirm patient identity.
- Time distance shielding
- Radiation dose to staff is reduced by minimizing time near sources, maximizing distance, and using appropriate lead shielding.
- Dose calibrator constancy check
- A daily constancy check verifies dose calibrator response using a long-lived source such as Cs-137, confirming stable measurement over time.
- Pregnancy screening
- Pregnancy and breastfeeding status are documented before radiopharmaceutical administration to assess risk and adjust the procedure.
- Extravasation reporting
- Extravasation of a radiopharmaceutical is documented and reported to the supervising technologist, with the site assessed and monitored.
- Radiopharmaceutical label check
- Before administration, staff verify the radiopharmaceutical label for radionuclide, activity, calibration time, and patient name.
- Decay formula
- Activity remaining equals initial activity multiplied by e raised to the negative decay constant times time, where decay constant equals 0.693 divided by half-life.