Examining Trends in Medical Imaging Studies and Radiation Dosage

M. Mahesh, MS, PhD, FAAPM, FACR, FACMP, FSCCT, FIOMP, Chair of the American College of Radiology^® (ACR^®) Commission on Medical Physics and Professor of Radiology and Cardiology at the Johns Hopkins University School of Medicine, contributed this piece.

A new report in Radiology examines trends in frequency and doses from medical radiation patient exposure in the United States and worldwide. The results indicate overall radiation exposure from medical imaging has declined over the past decade. This data can serve several purposes, including following and predicting trends, observing the effects of health planning policies, and comparing radiation doses from various practices — all of which can ultimately improve the quality of our care.

To conduct this study, my colleagues and I analyzed data from the United States National Council on Radiation Protection and Measurements (NRCP) Report 184 and the United Nations Scientific Committee on the Effects of Atomic Radiation survey. For NCRP Report 184, we extensively used ACR CT Dose Index Registry data for computing CT doses, along with literature published data.

The report gave the following estimates for the number of specific types of X-ray imaging exams performed in the United States:

• 74 million CT procedures (about 18% of the world’s estimated total).
• 275 million conventional radiology procedures (11% of the world total).
• 8.1 million interventional radiologic procedures (34% of the world total).
• 320 million dental radiographic examinations (29% of the world total).
• 13.5 million nuclear medicine procedures (34% of the world’s total).

We also identified promising trends in the United States, which include:

• The estimated number of CT examinations in the United States went up about 20% between 2006 and 2016, while the global number almost doubled.
• Even though the number of CT examinations in the United States increased by nearly 20% between 2006 and 2016, the overall average effective dose per person from CT decreased by nearly 6%.
• From 2006 to 2016, the annual average effective dose per person decreased worldwide from 0.65 to 0.56 mSv and de creased from 3.0 to 2.2 mSv in the United States in the same period.

The decline can be attributed to increased education, attempts to optimize doses, newer technologies, changes in practices and general awareness of radiation dose through social media campaigns such as @ImageWisely and @ImageGently.

The information provided in this report has many potential uses, including following and possibly predicting trends, observing the effects of health planning policies, and comparing radiation doses from various practices.