The evolution of the medical physicist

May 21, 2019
By Thomas J. Petrone

Medical applications of ionizing radiation have proliferated since their discovery in 1895, and adoption has significantly accelerated since 1980; tolerance of their harms to patients and staff has not.
The medical physicist’s role is to bridge this gap by protecting patient and staff safety while ensuring the optimal functioning of all medical technologies that use radiation.

The scope of the medical physicist’s job has expanded immensely, prompting increased sub-specialization across the field. Drawing on several decades of experience as a practicing medical physicist, I’m writing to tease out the implications of some of these changes. This series of columns will explain the technological developments, regulatory responses, and broader trends and controversies that have shaped medical physics over the past four decades.

This first column gives an overview of those changes before voicing a pressing question for the field: how do we balance medical physicists’ need for lengthy, specialized education and training with the shortage of these professionals looming on the horizon?

Technological and regulatory change
Prior to the 1980s, radiation was used in two places in the hospital: diagnostic radiology (mostly X-ray and fluoroscopy), and radiation oncology. In radiation oncology, one of the earlier, then-cutting-edge treatments was delivered by cobalt teletherapy units, a version of external beam radiation. By today's standards, this version of the therapy would be viewed as archaic, with unacceptable risks.

Tremendous advances in technology took place over the next two decades. Godfrey Hounsfield and Allan MacLeod Cormack were awarded the Nobel Prize in Medicine in 1979 for their work on X-ray computed tomography, or CT, which outpaced existing modalities and enabled a wholly new perspective on the body. The advent of the CT scanner constituted an explosive advance in the power, utility, and potential harms of diagnostic radiology.

Ten years later, CT had a rival in mainstream medicine: the MR machine, which became a commonplace installation in most modern hospitals. Instead of using ionizing radiation, MR uses strong magnetic fields and a radio frequency to look at soft tissue in a way that hadn’t been possible before — and with greater flexibility in terms of image manipulation (removing bone from the image, enhancing certain tissues preferentially, etc.).

At the same time as these developments, mammography was shifting from its status as a secondary application to a primary diagnostic focus. Due, in part, to the growing power of the breast cancer lobby, the regulation of mammography kept pace with these technological advances.

In medical physics in general, regulations derive from the standards put forth by national and international professional and scientific organizations. As existing technology becomes more complex or new technology is devised, new standards — and new regulations — crop up. And rightly so.

Medical physicists: supply versus demand
These leaps in diagnostic radiology, CT, MR, and modern-day mammography — plus their offspring, from CT angiography and MR angiography to MR spectroscopy of all sorts — have influenced the stalwart foundational technologies of radiography and fluoroscopy to make the leap to the digital realm. Once you digitize the imaged data and computers get faster and stronger, and coding software becomes ever more creative and robust, the technology can blow through earlier limitations of image scope, manipulation, enhancement, storage, computer aided diagnosis (CAD), and artificial intelligence (AI). A few years ago, the mainstream medical physicist had barely heard of the field known as “radiomics.” This is where large amounts of data are extracted from medical images in order to derive quantitative features through use of algorithms (which are being developed at a feverish pace). Coupled with “genomics”, radiomics promises to revolutionize medical diagnosis and treatment. Over the past decade, as conventional radiography and fluoroscopy have made that final, total transformation into digital, the medical physicist’s position has expanded yet again.

There is no end in sight to healthcare’s use of both diagnostic and therapeutic radiation-based technologies. Nor is there likely to be any relaxing of the exigencies of patient safety, diagnosis, and disease treatment. These two trends mean that the same specter looming across the medical industry looms over medical physics: demand is on the rise and supply is barely keeping up. With medical physicists from the Baby Boomer generation retiring, that gap is only likely to widen further.

The challenge of the current climate, then, is to get more people into the profession and provide them with the education they need to succeed in the twin missions of the medical physicist: optimal performance and maximal safety. Whether the answer is better recruitment, tiered educational requirements that allow for incremental practice along the way, new models of delivery, or the academic and training bar being reset and then raised gradually as residency slots come to match the graduate rate, the leading thinkers in the field today must confront the problem head on.

Thomas J. Petrone, Ph.D, DABR
About the author: Thomas J. Petrone, Ph.D., DABR, is the chief medical physicist and CEO of Petrone Associates. In practice for more than 30 years Petrone Associates delivers comprehensive consulting services to numerous healthcare organizations and facilities throughout the entire country.