March 08, 2021

Physicist Spotlight: Meet the Chair of the ACR Dose Index Registry Committee

In this issue, we talk with William F. Sensakovic, PhD, Chair of the Division of Medical Physics and Associate Professor at Mayo Clinic (Arizona), about the ACR Dose Index Registry (DIR) and how facilities can understand how much radiation they are using for various exams and how their numbers compare to those of their peers.

Q. Tell us a little bit about the DIR and its importance to improving quality and safety.

A. The DIR lets facilities compare their radiation dose indices to regional and national values. The information collected is masked, transmitted to the ACR® and stored in a database. We're gathering that data into a massive collection of dose metrics, larger than any single institution could ever put together on its own. That way, we can analyze it for information about the radiation we're exposing our patients to in order to help lower risk while still providing solid image quality to facilitate diagnosis. Participants in DIR receive quarterly feedback reports comparing their results to aggregate results by body part and exam type. The DIR is the largest registry under the ACR National Radiology Data Registry (NRDR®), and it currently has more than 3,100 institutions participating and has analyzed more than 100 million exams.

Q. Why is it important to compare dose indices against regional and national benchmarks?

A. The DIR lets facilities compare their CT dose indices to regional and national values. The benchmark reports allow facilities to understand how much radiation they are using and compare their doses for various exams to national averages, to similar institutions, and to other facilities in their geographic area, which is important because there are differences in both patient characteristics and radiology practice based on region. In other words, they can parse the feedback reports down to various comparisons to see how they’re doing and optimize their dose for various exams to bring them in line with standard practices.

Q. How is the DIR expanding to other modalities beyond CT doses?

A. For many years, the DIR has only benchmarked CT doses. Now, we are adding dose metrics for three other modalities: fluoroscopy, nuclear medicine/PET and digital radiography. We initially focused on CT for several reasons: In addition to being the single biggest contributor to patient dose, CT was also the most standardized in terms of reporting, which made it relatively straight forward to implement compared to other modalities. The success of the DIR created a kind of “push me-pull you” effect — seeing impactful analysis accomplished because of standardization encourages more standardization in our field, both for CT and other modalities.

While CT has been the easiest to benchmark due to existing standardization, it is not the only modality that exposes our patients to radiation. We have now turned our attention to other places where we could apply the value of benchmarking to improve quality and safety. The goal is to encourage standardization of the data for fluoroscopy, nuclear medicine/PET and digital radiography exams to create dose registries that allow comparisons to peers. This effort is an impetus toward standardization in places where it is lacking in the imaging community.

Q. When and how can facilities participate in the new DIR modules?

A. The DIR Fluoroscopy Module is now available for enrollment and data submission. Anyone who is currently sending data to the DIR can participate. You can read about the features of the new interactive fluoroscopy standardized DIR reports in the Knowledge Base . The pilots of the Nuclear Medicine/PET Module and the Digital Radiography Module are now underway. For more information about participating in any of the new DIR modules, contact

Q. How does participating in the DIR help radiologists and physicists be seen as valuable members on the patient care team?

A. The DIR is an easy reference tool, especially for radiologists who are not knowledgeable about doses. If you gain a little bit of knowledge about what typical doses are for a given exam, you can talk more intelligently about what the risks are to given patients and offer them reassurance about their safety. When speaking with referring physicians and patients, it can add confidence that you're doing things right. That can be important when calming a worried patient or when trying to convince a referring physician or patient that an exam that uses radiation is safe and important for their care.

What’s more, participating in the DIR is a key contributor to ongoing quality improvement efforts. Step one is to compare. Pull your benchmark reports for your scans and see if you deviate from your peers. Step two is to investigate. Follow up to determine why your doses are higher or lower than other comparable facilities. Step three is to modify, as needed. Then rinse and repeat. For larger institutions the reports can also be used to ensure that all machines are using similar doses across their fleet.

Q. How else can you use the data that’s being collected in the DIR?

A. I want to stress that quality improvement using DIR data is not only about lowering dose. If a facility’s doses are substantially lower than its peers, then it might indicate an opportunity to increase dose and by doing so increase image quality and hopefully diagnostic confidence. DIR data is also utilized within the ACR to inform other activities (e.g., ACR Appropriateness Criteria®) and outside the ACR by researchers who partner with the ACR for research initiatives. A link to request use of DIR data for research purposes is available on the NRDR Data Access and Publications Policy page.

The DIR is not only about dose management; it can also provide us with important insights into things like utilization and patient care. For example, a recent paper in the JACR® used DIR data to highlight the impact of COVID-19 on scanning volume: CT Volumes from 2,398 Radiology Practices in the United States: A Real-Time Indicator of the Effect of COVID-19 on Routine Care, January to September 2020 . Facility data contributed to the ACR registries helps us explore a wide range of questions about the practice of radiology and identify new areas for improvement.

Meet the Physicist

William F. Sensakovic, PhD, is an Associate Professor of Medical Physics and Chair of the Division of Radiology Medical Physics at Mayo Clinic in Arizona. He is also founder of Telerad Physics Teaching, LLC, which provides online radiological physics education services to medical professionals. He graduated with honors from The University of Chicago with undergraduate degrees in physics and mathematics and a doctorate in medical physics. He is an American Board of Radiology certified Diagnostic Medical Physicist and an American Board of Magnetic Resonance Safety (ABMRS) MR Safety Expert.

Sensakovic is Chair of the ACR Dose Index Registry, serves as a board member of the ABMRS and chairs the Medical Physics Education of Physicians Committee for the American Association of Physicists in Medicine. His research interests include artificial intelligence/image analysis, imaging and workflow optimization, and education. He is author of more than 40 scientific articles, 90 conference presentations and several book chapters and books.