For Medical Physicists, The Times They Are A-Changin’

The Medical Physics Community is Now Playing a Larger Role in Radiology Than Ever Before

Back in 2009, when the National Council on Radiation Protection and Measurements (NCRP) released NCRP Report No. 160, Ionizing Radiation Exposure of the United States Population, it revealed that medical radiation exposure had increased by more than 600 percent since the 1980s.1 I was a member of the NCRP Scientific Committee that published the report, and it was fascinating to watch both the radiology industry and the public react to these data.

An increased awareness of the risks associated with radiation in medical imaging has brought along a lot of change in radiology, and that change has had quite an impact on the roles of medical physicists. Historically, the diagnostic medical physics community has always worked behind the scenes, evaluating, teaching and researching the safety of imaging modalities.

Now, however, medical physicists have transformed from working behind the scenes in radiology to being involved in a lot of key discussions and helping make important decisions on a regular basis.

These are just a few examples of that change in action:

Bringing balance to radiation dose optimization: With the number of medical imaging procedures increasing in the United States and globally, the attention to the way procedures are performed and the amount of radiation patients are being exposed to has increased. Diagnostic medical physicists must now evaluate a modality for safety and help clinics optimize their protocols, meaning they are more active now than in the past.

One must be cautious when discussing radiation dose. Rather than automatically demanding a lower dose, the goal should be agreeing on a dose that is optimized. Consider dose and image quality as two sides of a coin: it is very important to balance the two to retain the value of imaging. Hubris often takes over and in such situations, too much focus is garnered toward dose reduction, which can jeopardize the image quality and overall value of a particular exam. Providing a balanced approach to optimize imaging procedures is a significant part of the job of any diagnostic medical physicist.

Accreditation and Joint Commission Requirements: Passage of the Medical Improvements for Patients and Providers Act (MIPPA) in 2008 paved the way for the accreditation requirements for advanced imaging modalities such as CT, MRI, PET and nuclear medicine procedures performed in outpatient imaging centers.2 The Joint Commission then made its own updates, extending the accreditation requirements for advanced imaging modalities located in hospitals.3 This opened up numerous opportunities for medical physicists. Many clinics and hospitals are hiring in-house diagnostic medical physicists or medical physics consulting companies to provide such services.

Radiation dose reporting requirements for CT: Interest in registering with the American College of Radiology Dose Index Registry (ACR-DIR) has increased throughout the U.S. due to radiation dose reporting requirements for CT being put into place. This also led to the introduction of many commercial products that track patient dose. Diagnostic medical physicists are now tasked with signing up with registries and/or implementing dose tracking systems, yet another example of the profession moving out from the shadows.

The ACR-DIR provides imaging groups with dose reports from similar groups while helping them implement changes as needed. However, it is important to recognize that this information can’t simply be filed away by a group to demonstrate compliance; it should be used to improve protocols and the overall quality of care provided by the group. The true essence of patient dose tracking or joining a registry is lost when it is not treated seriously!

Requirements for periodic CT protocol reviews: Radiologists, imaging technologists and medical physicists are now being brought together more and more to review protocols at a regular basis, which has further affected the diagnostic medical physics community. By continuously learning and keeping up with the latest scientific literature and technological changes, medical physicists can become an irreplaceable resource in providing protocol reviews, discussing patient safety issues, communicating benefits and risks of radiation, ensuring MR safety, and so on. In a changing landscape, this is a great opportunity to enhance the role of medical physicists in the realm of patient care.

Patient demand for radiation dose and risk information: With increased alertness about radiation risks aided by media hype, patients are often inquiring about their radiation dose information. And while patients are now more curious about radiation dose when they undergo CT exams, they are often confused when they try to find answers to their questions. This has opened up the opportunity for medical physicists to aid patients by providing proper perspective and discussion on the risks and benefits of a CT exam or any other medical x-ray exam. In order to provide a balanced viewpoint, the diagnostic medical physics community has to continuously keep abreast with scientific literature and learn how to effectively communicate radiation risks.

Entering the Refinement Phase

Events and activities that have changed the landscape for diagnostic medical physics up until now can be viewed as an implementation phase. We are now moving toward a refinement phase. A similar thing happened recently with CT equipment: The first part of the last decade was a constant drive to introduce CT scanners with an increasing number of slices, but that eventually slowed down and evolved into companies refining their equipment instead of just trying to win “the slice wars” for bragging rights.

The NCRP has embarked on creating an updated report on radiation exposure in the U.S. in 2019, and I am sure it will shed some light on the impact of all the hard work that has taken place in the last decade. Whatever it may find, the diagnostic medical physics community is ready for whatever challenges and opportunities may come its way in the coming years.

Mahadevappa Mahesh, MS, PhD, is a professor of radiology and cardiology at Johns Hopkins University School of Medicine in Baltimore and chief physicist at Johns Hopkins Hospital in Baltimore.


NCRP (2009). National Council on Radiation Protection and Measurements. Ionizing radiation exposure of the population of the United States, NCRP Report No. 160 (National Council on Radiation Protection and Measurements, Bethesda, Maryland).

Medicare Improvements for Patients and Providers Act of 2008. Accessed September 9, 2017.

The Joint Commission Diagnostic Imaging Standards. Accessed September 7, 2017.