ACRR flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- ALARA principle
- As Low As Reasonably Achievable; requires minimizing radiation dose by using time, distance, and shielding while considering economic and social factors.
- Inverse square law
- Radiation intensity is inversely proportional to the square of the distance from a point source; doubling distance reduces exposure to one-fourth.
- Half-value layer
- Thickness of a material that reduces photon intensity by half; used to specify shielding effectiveness for a given photon energy.
- Occupational dose limit
- ICRP/NCRP recommended limit of 20 mSv per year averaged over 5 years (100 mSv in 5 years) for radiation workers.
- Declared pregnant worker
- A radiation worker who voluntarily declares pregnancy; dose limit is 0.5 mSv per month or 5 mSv total gestation (NCRP).
- Effective dose
- Sum of tissue-weighted equivalent doses; used to estimate stochastic radiation risk across different tissues and radiation types.
- Photopeak
- Full-energy peak in a gamma spectrum corresponding to complete absorption of a gamma photon; used to set the energy window.
- Energy resolution
- Ability of a detector to distinguish gamma energies; expressed as percent FWHM of the photopeak; typically ≤10% for Tc-99m.
- Collimator selection
- Choosing a collimator based on photon energy: LEHR for Tc-99m, medium-energy for In-111, high-energy for I-131.
- Intrinsic uniformity
- Uniformity of detector response to a uniform source without collimator; integral within ±5% and differential within ±2% for daily QC.
- Center of rotation
- Alignment of the detector rotation axis with the reconstruction matrix center; misalignment causes ring artifacts in SPECT images.
- Dead time
- Count loss at high activity due to finite detector processing time; paralyzable or non-paralyzable models; keep count rates within camera limits.
- Tc-99m generator
- Device containing Mo-99 bound to alumina; Mo-99 decays to Tc-99m, which is eluted with 0.9% NaCl; Mo-99 breakthrough limit 0.15 kBq/MBq.
- Aluminum breakthrough
- Aluminum ion contamination of Tc-99m eluate from the generator column; limit ≤10 µg/mL; tested by colorimetric assay.
- Radiochemical purity
- Fraction of total activity in the desired chemical form; tested by chromatography (ITLC, paper, HPLC) for each radiopharmaceutical batch.
- Radionuclidic purity
- Fraction of total activity from the desired radionuclide; for Tc-99m eluate, ≥99.9% after allowing Mo-99 to decay? (verify).
- Tc-99m MDP
- Bone imaging agent that binds to hydroxyapatite; renal clearance; patient should hydrate and void bladder before imaging.
- F-18 FDG
- Glucose analog PET agent with 110-minute half-life; patient fasts ≥4 hours; physiologic uptake in brain, heart, kidneys, and bladder.
- I-131 therapy
- Unsealed source therapy for thyroid disease; requires pregnancy test, written directive, and patient release instructions per NRC 10 CFR 35.75.
- Extravasation management
- Stop injection, remove needle, elevate extremity, apply cold compress unless contraindicated, notify physician, and document the event.
- Anaphylactoid reaction
- Severe allergic-like response to radiopharmaceutical; stop administration, maintain airway, give oxygen, call for emergency help, administer epinephrine per protocol.
- Vasovagal reaction
- Fainting response during injection; place patient supine, elevate legs, monitor vital signs, and administer oxygen if needed.
- Pediatric dose scaling
- Adjust radiopharmaceutical dose by weight or body surface area per manufacturer or consensus guidelines; verify with a second qualified individual.
- Breastfeeding interruption
- Advise patient to pump and discard milk for a radionuclide-specific period (e.g., 24 hours for Tc-99m, longer for I-131) after administration.
- Patient identification
- Use two identifiers (name and date of birth or medical record number) before every dose administration to prevent wrong-patient errors.
- Universal precautions
- Treat all blood and body fluids as potentially infectious; use gloves, gown, and eye protection when splash risk exists.
- 10 CFR Part 35
- NRC regulations governing medical use of byproduct material; includes written directives, training, and patient release criteria.
- Patient release criteria
- 10 CFR 35.75 allows release if dose to any other individual from the exposed patient will not exceed 5 mSv (0.5 rem).
- Written directive
- Physician's written order for certain radiopharmaceutical therapies (e.g., I-131 >1.22 GBq) specifying radionuclide, dose, and route.
- Medical event
- Misadministration requiring NRC notification within 24 hours if dose differs by >20% from prescribed or effective dose >50 mSv.
- Informed consent
- Obtain before therapeutic procedures; document discussion of risks, benefits, and alternatives with the patient.
- Radiation Safety Committee
- Oversees the radiation safety program, reviews credentials of authorized users, and approves radiation safety policies.