Radiography shrinks, CT compounds
The single most important structural fact in imaging volumes is the crossover in what the world scans. Conventional radiography — still the majority of all examinations — has fallen 17% globally since 2006, as GI fluoroscopy and urography collapse into cross-sectional alternatives. CT has gone the other way, doubling to 403 million examinations a year. Because a CT delivers on the order of a hundred times the dose and several times the reading effort of a radiograph, the workload and dose burden of world imaging is rising much faster than raw exam counts suggest. Italy's 2023 national survey states it precisely: CT was 14.4% of examinations and 75.7% of the population dose.
Rich-world variation is about habits, not need
Among high-income countries CT utilisation spans nearly five-fold — South Korea near 250 exams per 1,000 people, Austria near 200, Australia at 151 — with no plausible epidemiological difference to explain it. Luxembourg's own national audit found only 61% of its CT requests appropriate against referral guidelines, in one of Europe's highest-utilisation systems. The MRI spread is similar (Austria 148 vs Poland 41). Utilisation reflects payment systems, gatekeeping, scanner access and medico-legal culture far more than disease burden — which is why "more imaging" and "better access" must never be read as synonyms.
The volume that never happens
The global average of 55 CT exams per 1,000 people is not a midpoint between rich countries — it is a number dragged down by billions of people who are scarcely imaged at all. Countries holding half the world's population perform 70% of its examinations and essentially all of its nuclear medicine; UNSCEAR measures a 15-fold spread in frequency across income levels. Set against the workforce map on our front page, the two gaps compound: the places with the fewest radiologists also generate the fewest images for them to read, so the true diagnostic deficit is far larger than either number alone implies.
And everywhere, exams outrun machines and readers
Across 16 OECD countries, the exam-to-scanner ratio rose for CT, MRI and PET in the large majority between 2011 and 2020 — the same fleets worked ever harder. The UK quantifies the human side: CT/MRI reporting demand growing 8–11% a year against roughly half that in workforce growth. The US CT curve — 26M exams in 1998, 93M in 2023 — is the whole story in one series: volume growth is the engine behind every other page on this site, from waits to burnout to the economics of reimbursement.