Working in physics: The business of medical physics

Medical physicists working in industry have some of the best jobs around, claims Thomas Rockwell Mackie. But to get there you need to put the time in at the clinic.

Industrial action

I have now been a medical physicist at the University of Wisconsin for more than 20 years. My academic career, like that of most other scientists, revolves around research, teaching and chasing grant money. Unlike most of my fellow academics, however, I am also an entrepreneur. My quest for research money has led me to start two companies, one of which — TomoTherapy Inc. — is a Nasdaq-traded public company with more than 600 employees, many of whom are physicists. This gives me a unique perspective on medical physics — a field that has very close links between hospitals, universities and industry.

Medical physics is one of the fastest growing areas of employment for physicists. They play crucial roles in radiology, nuclear medicine and radiation oncology, while many medical physicists also work in cardiology and neurology. These fields use very sophisticated and expensive equipment, and physicists are responsible for much of its design, testing and quality assurance. Medical physicists can be found in universities doing basic research into topics such as how radiation affects tissues; in industry, using these results to build new imaging and therapy systems; and finally in hospitals, maintaining this equipment and planning radiation treatments.

My first company developed a system for planning radiotherapy treatments that uses data from a computed tomography (CT) scanner to accurately compute the distribution of the radiation dose received by the patient during a treatment. The key feature of the system was dose-calculation algorithms that used data from Monte Carlo simulations of photons interacting with water in order to improve the computational accuracy.

The initial research for this system was funded by the University of Wisconsin Hospital, but it was unable to pay for the work to be brought to market. In 1992 I and three colleagues therefore started Geometrics Corporation to complete the development. After receiving approval to market the product from the US Food and Drug Administration (FDA), we sold the company to Philips Medical in 1996 and our system subsequently became the best-selling radiation therapy treatment-planning software of all time.

TomoTherapy was started for similar reasons. The TomoTherapy technology marries a clinical linear accelerator (linac) with a CT scanner. A TomoTherapy linac provides both the X-ray beam for treating the patient with radiotherapy and a lower-energy X-ray beam that can be used to obtain a CT scan of the patient. A patient can therefore be scanned with the low-energy X-rays — and thus the tumour precisely located — immediately before the treatment (high-energy X-rays) is administered.

The development of this technology was funded for the three years from 1994 by General Electric Medical Systems. In 1997, however, the firm decided to get out of the radiotherapy business, so I and my colleague Paul Reckwerdt founded TomoTherapy to get the first research prototype built. With the help of some very savvy business people and medical-device professionals, TomoTherapy has grown beyond our wildest dreams. I still serve as chairman of the board, and as a result I have reduced my academic commitments at the University of Wisconsin by 25%.

Getting in
So how can you become a medical physicist in industry? As far as TomoTherapy is concerned, we need staff with a broad range of experience, including those from traditional fields like nuclear physics, particle physics and astronomy. A knowledge of radiation detection, accelerator physics and materials science is sought-after for roles in both product development and customer service. Some medical-physics firms recruit students directly after they finish their PhD because their research topic is relevant to the company. But many organizations — particularly in radiotherapy — tend to recruit medical physicists who have spent a few years working in a clinic because these companies value the real-world skills that such experience instils.

Most older medical physicists entered the clinic through the "back door" — i.e. they were hired by a hospital while working in a basic discipline and then learned on the job. But that is getting rarer and is even being actively discouraged by the American College of Radiology. Instead, training is increasingly being provided via clinical "residencies", during which prospective medical physicists learn the necessary clinical skills under the supervision of experienced mentors. Typically these residencies are two years long and the pay is comparable to a postdoctoral fellowship. These programmes usually require you to have a PhD in physics, although some will accept candidates who have only a Masters degree.

These days, many medical physicists get into the field via an accredited medical-physics graduate programme. In the UK, for example, physics graduates can complete a taught MSc in medical physics either directly or by becoming a clinical-scientist trainee in the National Health Service. These courses — which are accredited by the Institute of Physics and Engineering in Medicine — take about two years to complete and involve lab work and practical experience in a hospital, as well as lecture-based learning. There are similar programmes in the US, which are accredited by the Committee on the Accreditation of Medical Physics Education Programs. Graduates of these courses are often hired directly into clinics as entry-level faculty members or as employees.

Lives in your hands
A major difference between medical physics and most other areas of physics is the level of regulation. Patients' lives are at stake, so the key to success is attention to detail — sloppiness in thought or action cannot be tolerated. A huge fraction of the costs incurred by medical companies stems from the need for stringent quality assurance and testing to make sure their products comply with regulations. The attitude and skills required of a medical physicist are not too different from what is demanded of a good experimental physicist, but the consequences of inaction or inattention may be much more serious.

This level of responsibility is accompanied by many benefits, however. Industrial physicists working in the medical field have many opportunities to advance to a high-level managerial and business role. Potential barriers — such as a lack of business knowledge — can be overcome by taking an MBA or one of the short courses in, say, accounting, finance or marketing that are focused on the career needs of scientists working in industry.

Another attraction of working in industry is the wide variety of people you encounter. A physicist working in a university lab often has a rather narrow range of experiences, often associating only with their group, both at work and socially. This is certainly not true in the medical field. Industrial medical physicists are required to work with doctors, medical administrators and technicians in hospitals, as well as service engineers and assembly personnel within their company.

The financial and personal rewards for physicists in the medical-device business are also high and the quality of the work environment is generally better than in a university. Ultimately, though, nothing can beat the job satisfaction of knowing that your work has an immediate human benefit.

About the author
Thomas Rockwell Mackie is a professor of medical physics at the University of Wisconsin in the US and chairman of the board of TomoTherapy.


This article originally appeared in the December 2007 issue of Physics World

last edited: July 31, 2014



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