Free CNMT Exam Flashcards

After each physical half-life, activity is halved. Use A = A0 × (1/2)^(elapsed time / half-life) to decay-correct an assay to the administration or imaging time.

Compton scatter deflects a photon and lowers its energy, adding unwanted counts. Photoelectric absorption transfers the photon's energy completely and removes it from the beam.

An ionization chamber measures radiation by collecting ion pairs produced in a gas. A dose calibrator uses this principle to assay radiopharmaceutical activity.

Keep radiation exposure as low as reasonably achievable by minimizing time near a source, maximizing distance, and using appropriate shielding.

For a point source, exposure rate changes inversely with the square of distance. Doubling the distance reduces the rate to one-quarter.

Deterministic effects have a threshold and become more severe with dose, such as skin injury. Stochastic effects have no assumed threshold; dose increases their probability, not their severity.

A dosimeter documents occupational exposure. Wear and handle the assigned badge exactly as the radiation-safety program directs; a fetal badge follows the declared-pregnancy monitoring process.

Protect people first: stop the spread, warn others, restrict the area, and follow the department's spill procedure and radiation-safety instructions before cleanup.

Receipt, storage, surveys, disposal, equipment checks, and required patient or personnel exposure information must be documented under the facility's license and procedures.

Eluate is the daughter radionuclide solution removed from a generator. Before using it, follow required quality-control checks and verify that it is suitable for the intended preparation.

Mo-99 breakthrough is parent radionuclide contamination in Tc-99m generator eluate. A failed breakthrough test means the eluate must not be used until handled under the applicable procedure.

Radiochemical purity is the fraction of total radioactivity present in the intended chemical form. ITLC is a common method for checking whether a prepared radiopharmaceutical meets its specification.

Radiochemical purity asks whether the radionuclide is bound in the correct chemical form. Radionuclidic purity asks whether the sample contains the intended radionuclide rather than an unwanted radionuclide.

Assay a patient dose in the dose calibrator using the correct setting and record the activity at its stated time. Decay correction connects the measured activity to the planned administration time.

Tc-99m macroaggregated albumin is used for pulmonary perfusion imaging. Its particles lodge temporarily in pulmonary capillaries, so injection technique and patient screening matter.

Tc-99m methylene diphosphonate localizes in bone and is used for skeletal imaging. Uptake reflects osteoblastic activity and blood flow rather than a diagnosis by itself.

These Tc-99m agents are used for myocardial perfusion imaging. Their myocardial distribution is interpreted with the stress-rest protocol and image-quality information.

I-123 sodium iodide is commonly used for thyroid imaging or uptake studies. I-131 sodium iodide is used in thyroid therapy and can also be used for whole-body survey applications.

F-18 FDG is a glucose analog used in PET. Tissue uptake reflects glucose metabolism, so preparation and blood-glucose review are important to image quality and interpretation.

Tc-99m DMSA is used for renal cortical imaging. It helps assess functioning renal cortex and relative cortical distribution.

MAG3 is commonly used for tubular secretion and effective renal plasma-flow assessment. DTPA is filtered by glomeruli and is used in studies involving glomerular filtration.

RBC labeling requires strict patient-and-sample identification before reinjection. Labeled RBCs are used in applications such as gastrointestinal bleeding and gated cardiac blood-pool imaging.

Constancy checks whether a dose calibrator gives reproducible readings for a long-lived reference source. It is the routine check for day-to-day stability.

Accuracy testing compares the calibrator reading with the known activity of traceable standards. It asks whether the instrument is measuring activity correctly.

Linearity testing confirms that measured activity remains accurate as a source decays across the range of activities used in the department.

A geometry test checks whether measured activity changes appropriately with source volume or container shape. It identifies volume-dependent measurement error.

Uniformity QC checks whether a uniform radiation field produces a uniform image. Nonuniformity can create artifacts that mimic or obscure clinical findings.

Center-of-rotation QC verifies that the camera rotates around the correct reconstruction center. An error can blur structures or create ring-like artifacts in SPECT images.

Pulse-height analysis selects an energy window around the photopeak. Proper window placement accepts desired photons while limiting scatter and unwanted energies.

Attenuation correction compensates for photon loss in tissue. In hybrid imaging, verify registration and recognize that correction can improve images but may also introduce artifacts.

A V/Q study compares regional ventilation with regional pulmonary perfusion. The value lies in the pattern of both components, not in either image alone.

A three-phase bone study acquires flow, blood-pool, and delayed skeletal images. The phases help distinguish early perfusion or soft-tissue findings from delayed osseous uptake.

Lymphoscintigraphy identifies lymphatic drainage from a tumor site to sentinel nodes. Clear communication of injection site, timing, and localization supports surgery planning.

A diuretic renogram evaluates renal drainage after a diuretic challenge. Hydration, timing, patient position, and acquisition protocol affect the study's usefulness.

ACE-inhibitor renography can help evaluate suspected renovascular hypertension by comparing renal function under the protocol's medication conditions.

A thyroid uptake study measures iodine trapping over time. Thyroid scintigraphy shows the distribution of tracer within the gland; the two procedures answer related but different questions.

Stress and rest images compare myocardial tracer distribution under different physiologic conditions. Follow the selected exercise or pharmacologic stress protocol and monitor the patient throughout.

ECG gating sorts counts by cardiac cycle, allowing assessment of ventricular function in addition to perfusion. Poor ECG signal or arrhythmia can degrade gated data.

FDG PET preparation aims to control factors that alter glucose metabolism. Confirm the protocol's fasting instructions, glucose assessment, activity restrictions, and uptake-time conditions.

Gastric-emptying studies measure movement of a standardized meal from the stomach. Meal completion and prescribed imaging times are essential for a valid result.

Hepatobiliary imaging follows tracer through the liver and biliary system. When a gallbladder ejection fraction is requested, the stimulation protocol and exact timing must be followed.

A labeled-RBC bleeding study uses serial imaging to detect and localize active gastrointestinal bleeding. Delayed images can be useful when bleeding is intermittent.

Dopamine transporter imaging evaluates striatal dopamine-transporter binding. It is a functional brain study whose patient preparation and acquisition follow the specific protocol.

A cerebral perfusion study may be used as an ancillary test under the governing clinical policy. Technologists follow the approved protocol, document the acquisition, and do not independently make the clinical determination.

Before administering a radiopharmaceutical, use the department's required patient identifiers and reconcile the patient, order, agent, route, activity, and administration time.

Screening gathers information that can change safety or protocol: relevant history, current medications, allergies or prior reactions, contraindications, pregnancy status when applicable, and pertinent labs.

Choose transfer and support equipment based on the patient's mobility and condition. Protect the patient, staff, IV lines, drainage devices, and imaging equipment during positioning.

For therapies that require a written directive, verify the authorized directive and patient information before administration, then document the treatment according to the facility procedure.

Before release after radionuclide therapy, provide the patient and caregivers the required instructions on precautions, restrictions, and whom to contact, consistent with the authorized protocol.

CT may provide attenuation correction, anatomic localization, or diagnostic imaging depending on the ordered protocol. Do not assume every CT in a hybrid study has the same purpose or technique.