First Medicare ExRad study reveals wide variation in CT radiation

The first study to examine how imaging facilities perform on the new Medicare "ExRad" measure shows that radiation doses used for the same type of CT scan vary widely from one facility to the next.

The study, "Early Implementation Performance of the CMS Electronic Clinical Quality Measure for Excessive Radiation Dose or Inadequate Image Quality in Diagnostic Computed Tomography: An Evaluation of 254 Facilities," published Nov. 3 in the Journal of the American College of Radiology^® (JACR^®), examines how facilities perform on the ExRad measure, a Medicare quality measure that evaluates whether a CT scan used more radiation than necessary for the patient's indication or produced images too noisy to interpret. The study covers 254 hospitals and imaging practices and 783,634 adult CT scans over 16 months.

Study findings reveal that nearly one in three scans (30.7%) exceeded the radiation threshold for its exam type, while almost none (0.06%) fell short on image quality - meaning the improvement opportunity is in dose, not picture quality. Facility scores ranged from less than 1% to more than 90% of scans out-of-range for using excessive dose. Most facilities performed well on some types of CT and poorly on others, with a typical gap of 74 percentage points between a facility's best and worst exam category.

According to study author Rebecca Smith-Bindman, MD, professor in residence of Epidemiology and Biostatistics, and Obstetrics, Gynecology and Reproductive Medicine at the University of California, San Francisco, while CT scans are essential to modern medicine, exams in excess of the recommended threshold may carry a small radiation-related lifetime cancer risk. "The same CT scan can expose one patient to many times the radiation of another, depending simply on where that patient is imaged - and that variation is entirely modifiable," said Smith-Bindman, "What these data show is that excellent performance is already achievable with the scanners hospitals have today: some facilities are at near-zero out-of-range rates in the exact categories where others exceed 90%."

Three common exam types - routine abdomen and pelvis, chest and head - accounted for 72% of all out-of-range scans. Because some facilities already achieve near-zero rates in the very categories where others struggle, the findings show that lower doses are achievable with today's equipment. Smith-Bindman says findings suggest each facility needs its own category-level results to know which protocols to target.

Lowering the dose is no longer a technology problem - it's a measurement and feedback problem. This is the first time facilities have received automated, protocol-level feedback on radiation doses as a routine part of quality reporting."

Rebecca Smith-Bindman, MD, professor in residence of Epidemiology and Biostatistics, and Obstetrics, Gynecology and Reproductive Medicine, University of California, San Francisco