ABR NMP cheat sheet

Radionuclide half-life: T½ = ln(2)/λ; activity A(t) = A₀ e^(−λt); after n half-lives, remaining fraction = (1/2)^n.

Common SPECT radionuclides: Tc-99m (T½ = 6.01 h, γ 140.5 keV), I-123 (13.2 h, 159 keV), In-111 (2.80 d, 171 & 245 keV), Ga-67 (78.3 h, 93–300 keV).

Common PET radionuclides: F-18 (109.8 min, β⁺ 634 keV), C-11 (20.4 min), N-13 (9.97 min), O-15 (2.04 min); annihilation photons 511 keV.

Photomultiplier tube (PMT) gain G = δ^n where δ is dynode secondary-emission ratio and n is number of dynodes; typical δ ≈ 3–5, n ≈ 10.

Anger logic position: X = (Σ E_i x_i)/(Σ E_i), Y = (Σ E_i y_i)/(Σ E_i); energy signal Z = Σ E_i used for pulse-height (photopeak) discrimination.

SPECT resolution: collimator resolution R_coll ≈ d (l_eff + b)/l_eff, where d = hole diameter, l_eff = effective hole length, b = source-to-collimator distance; sensitivity ∝ d²/l_eff².

PET coincidence timing window typically 4–12 ns; random coincidence rate R = 2 τ S₁ S₂ (τ = timing window, S = singles rates); true-to-random improves with lower activity and shorter τ.

Image quality metrics: uniformity (integral & differential), spatial resolution (FWHM), sensitivity (cps/MBq), energy resolution (FWHM at photopeak, e.g., NaI(Tl) ≈ 6–7% at 140 keV), and count-rate linearity.

Dosimetry: MIRD schema absorbed dose D = Ã · S (Ã = cumulated activity, S = absorbed dose per unit cumulated activity); effective dose uses tissue weighting factors w_T.

Radiation safety: ALARA; time-distance-shielding; dose rate from a point source follows inverse-square; HVL = 0.693/μ for narrow-beam attenuation.

Quality control: daily uniformity & energy peaking, weekly resolution/sensitivity, quarterly/intrinsic flood; PET daily blank scan and normalization; NEMA NU 2 performance standards.

Radiopharmaceutical yield: labeling efficiency = (activity bound)/(total activity) × 100%; radiochemical purity assessed by chromatography (e.g., ITLC, HPLC).

Informed consent requires disclosure of purpose, risks, benefits, alternatives, and the right to withdraw; documentation must be in the patient record.

Patient confidentiality: HIPAA Privacy Rule permits disclosure for treatment, payment, and operations; minimum necessary standard applies.

Research ethics: Belmont Report principles - respect for persons, beneficence, justice; IRB approval and ongoing review required for human-subjects research.

Conflicts of interest must be disclosed (financial and non-financial); recusal from decisions where impartiality could be compromised.

Scope of practice: perform only procedures for which you are credentialed and competent; refer questions outside expertise to qualified colleagues.

Reporting obligations: suspected child/elder abuse, impaired colleagues, and serious safety events must be reported per institutional and legal requirements.

Radiation ethics: justification (benefit > risk), optimization (ALARA), and dose limits/constraints; pregnant patients and workers require special consideration.

Professional conduct: honesty in reporting results, avoiding plagiarism and fabrication, respecting patient autonomy, and maintaining competence through continuing education.

Data integrity: retain raw data and analysis records per institutional policy; avoid selective reporting; correct errors transparently.