Start from the clinical question.

Fleischner, Lung-RADS, Brock, Mayo, Herder and volume doubling time — which nodule tool matches an incidental finding versus a screening CT.

Wells, Geneva, PERC, age-adjusted D-dimer, PESI and CTPA burden — pretest probability, who to scan, and how a positive study is described.

LI-RADS, liver fat and volume, Child-Pugh, ALBI, FIB-4, APRI and BCLC — lesion category, liver function, and treatment stage in one place.

Bosniak classification, RENAL nephrometry and the AAST kidney injury scale — cyst category, solid-mass complexity, and trauma grading.

ACR TI-RADS, EU-TIRADS, ATA and Kwak patterns, plus thyroid volume — which nodule system you are actually applying.

PI-RADS, PSA density, PSMA-RADS and the multiparametric prostate protocol — detection, density, and the scan itself.

ASPECTS, pc-ASPECTS, ICH volume and ICH score, NASCET, mTICI and ABCD2 — acute ischaemia, haemorrhage, stenosis and TIA.

Canadian CT Head Rule, PECARN, NEXUS, Marshall and Rotterdam — who needs a scan, and how a traumatic brain injury CT is graded.

O-RADS ultrasound, O-RADS MRI, IOTA Simple Rules, ADNEX and RMI — which adnexal risk system matches the scan you have.

Agatston score, MESA percentile and CAD-RADS — calcium burden, how that burden compares, and how a coronary CTA is reported.