ACRR cheat sheet

Universal precautions apply to all patients; treat all blood and body fluids as potentially infectious.

Standard precaution PPE for radiopharmaceutical administration: gloves, gown, and eye protection when splash risk exists.

Extravasation management: stop injection, remove needle, elevate extremity, apply cold compress (unless contraindicated), notify physician, document.

Vasovagal reaction: place patient supine, elevate legs, monitor vital signs, administer oxygen if needed.

Anaphylactoid reaction to radiopharmaceutical: stop administration, maintain airway, give oxygen, call for emergency assistance, administer epinephrine per protocol.

Pediatric dosing: use weight-based or body-surface-area-based scaling per manufacturer or consensus guidelines; verify dose with a second qualified individual.

Pregnancy screening: ask about pregnancy and breastfeeding before administering radiopharmaceuticals; document response.

Breastfeeding interruption: advise patients to pump and discard milk for the period specified for the radionuclide (e.g., 24 h for Tc-99m, longer for I-131).

Patient identification: use two identifiers (name and date of birth or medical record number) before every dose administration.

Gamma camera detector: NaI(Tl) crystal converts gamma photons to light; photomultiplier tubes convert light to electrical signal.

Photopeak: full-energy peak in gamma spectrum; photopeak energy window centered on the gamma emission energy (e.g., 140 keV for Tc-99m).

Energy resolution: ability to distinguish photopeaks; typically ≤10% FWHM for Tc-99m at 140 keV in a NaI(Tl) camera.

Intrinsic spatial resolution improves with thinner crystal and better light guide; degrades with increasing distance from collimator.

Collimator selection: low-energy high-resolution (LEHR) for Tc-99m; medium-energy for In-111/Ga-67; high-energy for I-131.

Sensitivity vs. resolution trade-off: smaller collimator hole diameter improves resolution but reduces sensitivity.

Dead time: count loss at high activity; paralyzable vs. non-paralyzable models; keep count rates within camera's specified limit.

Uniformity: intrinsic flood field should be within ±5% (integral) and ±2% (differential) for a uniform source; daily QC.

Center of rotation (COR): alignment of detector rotation axis; misalignment causes ring artifacts in SPECT.

ALARA: keep radiation dose as low as reasonably achievable, considering economic and social factors.

Inverse square law: intensity ∝ 1/d²; doubling distance reduces exposure to one-fourth.

Half-value layer (HVL): thickness of material that reduces photon intensity by half; number of HVLs = log2(I0/I).

Time, distance, shielding: three basic principles of external radiation protection.

Occupational dose limits (ICRP/NCRP): 20 mSv/year averaged over 5 years (100 mSv in 5 years) for radiation workers; 1 mSv/year for public.

Equivalent dose limits: lens of eye 20 mSv/year (ICRP) or 150 mSv/year (NCRP); extremities/skin 500 mSv/year.

Pregnancy: declared pregnant worker dose limit 0.5 mSv per month or 5 mSv total gestation (NCRP).

Dose equivalent: H = D × Q × N; for gamma and beta, Q = 1; for alpha, Q = 20.

Effective dose: sum of tissue-weighted equivalent doses; used for stochastic risk estimation.

Tc-99m generator: Mo-99 (t½ 66 h) decays to Tc-99m (t½ 6 h); elute with 0.9% NaCl; check Mo-99 breakthrough limit ≤0.15 kBq Mo-99 per MBq Tc-99m (0.15 µCi/mCi).

Alumina column breakthrough: test eluate for aluminum ion; limit ≤10 µg/mL; use colorimetric assay.

Radionuclidic purity: fraction of total activity from the desired radionuclide; for Tc-99m eluate, ≥99.9% after decay of Mo-99? (verify).

Radiochemical purity: fraction of activity in the desired chemical form; test by chromatography (e.g., ITLC, paper, HPLC).

Tc-99m sulfur colloid: particles 0.1–1 µm; used for liver/spleen and marrow imaging; heat denaturation required.

Tc-99m MDP: bone imaging agent; binds to hydroxyapatite; renal clearance; hydrate patient and void bladder before imaging.

I-131 therapy: administer after confirming negative pregnancy test; block thyroid with non-radioactive iodine if indicated; patient release criteria per NRC 10 CFR 35.75.

FDG PET: F-18 t½ 110 min; glucose analog; patient fast ≥4 h; check blood glucose; uptake in brain, heart, kidneys, bladder.

Quality control schedule: daily-camera uniformity/energy; weekly-radionuclidic purity? (verify); monthly-instrument calibration; each batch-radiochemical purity.

NRC 10 CFR Part 35: medical use of byproduct material; requires written directives for certain therapies (e.g., I-131 >1.22 GBq).

10 CFR 35.75: patient release criteria; dose to any other individual from exposed patient must not exceed 5 mSv (0.5 rem).

10 CFR 35.92: training requirements for authorized users, medical physicists, and radiation safety officers.

10 CFR 35.315: safety precautions for patients treated with unsealed sources; written instructions if dose rate >5 mrem/h at 1 m.

10 CFR 35.63: determination of dosages of unsealed byproduct material; must be verified by a qualified individual before administration.

Informed consent: must be obtained before therapeutic procedures; document risks, benefits, and alternatives.

Record retention: NRC requires retention of records of dose measurements, surveys, and training for specified periods (e.g., 3 years for some, longer for others).

Medical event (misadministration): notify NRC within 24 hours if certain criteria met (e.g., dose differs by >20% from prescribed, or >50 mSv effective dose).

Radiation Safety Committee: oversees radiation safety program, reviews credentials, and approves policies.