PROTECTION VI: Worldwide Dose Survey of Cardiac CT in Clinical Practice

The PROTECTION VI registry prospectively enrolled 4,502 patients undergoing cardiac CT angiography (CCTA) across 46 sites in 17 countries in 2017, characterizing real-world radiation doses and comparing them with the PROTECTION I registry from 2007 to quantify the decade-long dose reduction achieved through technological advancement.

Mean effective radiation dose decreased from 12.0 mSv in 2007 (PROTECTION I) to 3.5 mSv in 2017 — a 71% reduction over a decade. This reduction was driven by prospective ECG gating (adopted in the majority of scans by 2017), high-pitch dual-source CT acquisition, and iterative reconstruction algorithms. A subset of studies achieved doses below 1 mSv. Median DLP fell from 861 mGy·cm to 349 mGy·cm.

The practical importance of this data is high. Radiation concerns have historically been among the main objections to routine CCTA screening, particularly in younger patients who face the longest exposure window for radiation-related cancer risk. The documented 71% dose reduction over one decade demonstrates that the technology is evolving rapidly in a patient-protective direction, and that modern CCTA exposures are substantially lower than older estimates or older-technology benchmarks.

At 3.5 mSv median (achievable below 1 mSv in optimized protocols), modern CCTA carries approximately the same effective dose as a mammogram or 1.5 years of background radiation — a risk level that is clinically acceptable when balanced against the diagnostic benefit of identifying high-risk coronary anatomy.

We rate the evidence strong. A large prospective multicenter registry documenting a 71% radiation dose reduction in cardiac CT over the decade 2007–2017 — important evidence for the safety trajectory of CCTA as a routine diagnostic tool for coronary atherosclerosis assessment.