March 10, 2020

Q&A With Mahadevappa Mahesh, MS, PhD, FAAPM, FACR, FIOMP

In this issue, we talk with Mahadevappa Mahesh, MS, PhD, FAAPM, FACR, FIOMP, Chair of the ACR Commission on Medical Physics and professor of radiology and medicine at the Johns Hopkins University School of Medicine, about findings from Report No. 184 – Medical Radiation Exposure of Patients in the United States (2019), which shows a reduction in medical radiation doses from 2006 to 2016.

Q. What does the new report by the National Council on Radiation Protection and Measurements (NCRP) tell us about average medical radiation doses in the United States?

A. A new report by the NCRP shows that the average diagnostic and interventional medical radiation doses are decreasing in the U.S. The 2019 report, Report No. 184 – Medical Radiation Exposure of Patients in the United States (2019), analyzed radiation exposure in the U.S. population for 2016 and compared to 2006. The study shows a 15 to 20% reduction in radiation doses in the U.S. population over 10 years. In nuclear medicine, radiation dose per person decreased by more than 50%, primarily due to a declining number of procedures. On the other hand, the number of CT scans increased by 20% over the 10-year period, but the average dose to the patient per CT exam actually decreased by 6%.

Q. What is the significance of this report?

A. The 2019 NCRP report demonstrates that medical radiation dose is on the decline, which is a positive shift from a decade ago when doses were increasing significantly. The 2019 report is an update of a study published in 2009 — NCRP Report No. 160, Ionizing Radiation Exposure of the Population of the United States. Ten years ago, that report generated a lot of news because it showed that medical radiation exposure had significantly increased from the early 1980s to 2006. Primarily, that increase in radiation was due to a significant increase in the number of CT scans being performed, but it raised the alarm in the medical community that we needed to act to address increasing radiation doses and enhance patient safety.

Q. What factors contributed to the substantial decline in radiation dose from 2006 to 2016?

A. A number of factors have contributed to the decline, among them, the advancements in imaging technology and protocols, which enable better quality images at lower doses. For example, now almost every patient having a CT scan will have the dose modulation applied, which means the scanner will automatically change the dose based on the patient size. In addition, another big contributor to dose reduction in CT has been the impact of radiology campaigns such as Image Wisely®  and Image Gently® , which increased awareness and understanding of medical radiation dose and dose optimization. Other factors include legislation requiring accreditation of advanced imaging modalities. Among the approved accrediting bodies, the rigor of ACR accreditation programs , which are unique, plus the advent of dose registries like the ACR Dose Index Registry (DIR) have also contributed to the decline. The ACR DIR lets facilities compare their CT doses to regional and national values and bring their radiation doses in line with industry benchmarks.

Q. What’s the key takeaway message from the report?

A. For the past 10 years, all the efforts being done nationally by the radiology specialty seem to be making a difference. These data show the medical community can continue to leverage the benefits of radiological procedures for patients while reducing dose. While we can take comfort that what we are doing is paying off, it doesn't mean we should become complacent. We need to continue to maintain the same type of attention to dose reduction and optimization, so that we can provide better-quality images at a much lower radiation dose to our patients.

Q. What actions should radiologists and medical physicists take to achieve the goal of increased quality and lower dose?

A. First, access and read the report to better understand the numbers, the causes and what can be done to optimize protocols. The report also has appendices with dose tables for various procedures. Second, participate in DIR and use the comparison reports to analyze your performance, examine your protocols and identify areas for improvement. Pay attention to what the numbers are telling you; don’t just use the DIR to check a box. More and more patients are asking about radiation dose, so when you’re asked these questions, you need to be able to answer with confidence about what you’re doing to optimize dose. Third, take advantage of the ACR accreditation programs, which go a step beyond evaluating protocols and actually have reviewers look at phantom images to address the medical physics side of dose optimization. Finally, ensure you are collaborating with referring physicians and communicating with patients about evidence-based guidelines for appropriate imaging. Every scan should be clinically appropriate for the patient’s condition.

Q. How can information like this guide discussions with patients?

A. When my family, friends and colleagues ask me where they should go to get a CT scan, I suggest they ask three questions first. One: Is your scanner routinely inspected or checked for quality and safety? Two: Does your facility have a team that reviews the scanner protocols on a regular basis? Three: Does the scanner have accreditation, particularly from ACR? If they answer “yes” to all three, it's a safe place to go and get your scan done.

Q. What advice do you have for the specialty about becoming more engaged in quality and safety?

A. Quality and safety should not be in the background. If we don't pay active attention, complacency sets in. Quality and safety must be a regular practice, so it becomes second nature. Don't just go through a quality and safety checklist. Think about it as if someone in your own family is getting every CT scan. You want to ensure they get the best imaging exam so they can get the best diagnoses and the best treatment. If you think that way every time, quality and safety will come naturally.

Q. Where can radiologists learn more information about the report and its implications?

A. I recently hosted a two-part discussion on Image Wisely® Facebook Live about the findings from the NCRP Report 184: Medical Radiation Exposure of Patients in the United States. You can access Part 1 and Part 2 on demand. Access the Radiology journal to read the executive summary of the report and the JACR for an upcoming series of articles about the report and what we can learn about dose optimization going forward.

Meet the Medical Physicist

Mahadevappa Mahesh, MS, PhD, FAAPM, FACR, FIOMP, is Professor of Radiology and Cardiology at the Johns Hopkins University School of Medicine, Baltimore, MD. He is also the Chief Physicist at the Johns Hopkins Hospital in Baltimore. Dr. Mahesh is board certified from the American Board of Radiology in diagnostic radiological physics and is a member of the Radiation Control Advisory Board for the State of Maryland. His research interests are in medical imaging, particularly in areas of computed tomography, interventional fluoroscopy and digital mammography.

Dr. Mahesh is Chair of the ACR Physics Commission, member of the ACR Board of Chancellors and past-President of the Maryland Radiological Society. He also serves as the subject matter expert for the International Atomic Energy Agency and is the national contact person for the United Nations Scientific Committee on the Effects of Atomic Radiation. In addition, Dr. Mahesh is an NCRP council member and served as Vice Chair for NCRP SC 4-9, the scientific committee that wrote the NCRP Report 184: Medical Radiation Exposure of Patients in the United States.