September 2004 - Radiology Malaysia Editor, Dr Evelyn Ho, conducts an electronic interview with Prof Dr John R. Cameron, a medical physicist who has devoted his life to the application of physics in the medical world. He invented bone densitometry (a method and equipment to measure bone density) in the 1960s. Since treatment has been found for treating osteoporosis, bone densitometers have become popular world wide.
 

John is a pioneer and world leader in medical physics. His work has covered such diverse topics as radiation dosimetry (TLD), photon absorptiometry method of measuring bone mineral, the physics of the human body and the design and manufacture of quality control instruments for x-ray machines.

In 1989 John developed the simple BERT method for explaining radiation to x-ray patients. The radiation dose to the patient is explained in terms of how long it would take to get the same dose from background radiation. (BERT = Background Equivalent Radiation Time.) For example, a chest x-ray is about equal to a week of background radiation. See “Are X-rays Safe?"

John has been honored by his scientific and medical colleagues for his scientific contributions. He received the Coolidge Award from the American Association of Medical Physics in 1980 and the International Organization for Medical Physics (IOMP) awarded him the first Marie Sklodowska Curie award for his contributions to medical physics education in developing countries in the year 2000. In 1995 the Radiological Society of North America gave him the first Roentgen Centennial Commemorative Medal - it is given every hundred years! In 2002 the American College of Radiology elected him an Honorary Fellow of the ACR. 

In 2004, in order to celebrate his outstanding achievements, the 3^rd South East Asian Congress of Medical Physics held in Malaysia has inaugurated The SEACOMP John Cameron Lecture. A distinguished medical physicist, Professor Dr Willi A. Kalender from Erlangen University, Germany, who is a foremost researcher in computed tomography delivered the first John Cameron lecture. (Willi Kalendar is responsible for introducing spiral and multislice imaging methods and developing methods for quantifying bone mineral density using CT.)

Some of the information above has been reproduced with permission from the Homepage of Prof Dr John Cameron.
 

Question: How would you define your profession?
JC: Medical physics is an applied area of physics. Most medical physicists work in the physics of radiation oncology making sure that the desired dose is given to the cancer and the dose to normal tissues are minimized. Medical physicists work in cooperation with doctors. A few medical physicists devote their time to research and teaching. A few get involved with administrative duties. Many medical physicists take responsibility for radiation safety in their hospital. 

Question: How and why did you go into Medical Physics/your profession? Why the switch from nuclear to medical physics?
JC: I found I liked practical applications of physics that are of benefit to society rather than basic research in nuclear physics. Nuclear physics is interesting but it is unlikely to help society.  I am sure that I have been much more useful to society as a medical physicist. When I entered medical physics in 1958 there were fewer than 100 in the U.S. and I could see many opportunities to apply my knowledge of nuclear physics. I started the nuclear medicine laboratory at UW Hospitals in 1959 and trained radiology residents in the field. It was 1965 before they found a trained MD (doctor) to take over my role. 

Question: In the beginning were you ever afraid of radiation? (I am aware you now believe that a moderate dose rate radiation is probably beneficial.)
JC: When I entered the field in July 1958 I believed what they told me about radiation risks. I spent much effort reducing the dose to patients in radiology. In 1970 I realized that there was negligible risk from x-rays but many radiographs had poor image quality so that the risk from a false negative was significant. 

We developed simple test tools to optimize imaging parameters. No company was interested in our idea. The radiologists said quality control tools weren't necessary as they would see any problem in the x-ray image. In 1974 I started the nonprofit Radiation Measurements Inc (RMI) to manufacture and sell these QC test tools. The profits and my salary from RMI were donated to the University to support medical physics research. 

Question: What do you find professionally satisfying about your profession? (What do you like about your career/profession?)
JC: I found collaborating with congenial doctors about problems that physicists could help solve was very satisfying. I also like educating anybody who would listen! 

Question: Your first major discovery/major project - What was it, how was it, what happened after this?
JC: In 1959 I learned from Dr Lester Paul, Chair of Radiology at UW that there was no method to detect early osteoporosis. Many women were dying each year from broken hips. I invented bone densitometry in the early 1960s. It was of little interest at first because there was no known treatment.  My invention was used to evaluate the different possible therapies. There are now over 50,000 bone densitometers in the world. I doubt if more than 50 radiologists in the world know who invented the instrument. I have received little recognition for this contribution.

I am not unhappy that my contribution was not recognized. I am sure it helped my career. Many of my graduate students received useful training doing their Ph.D. thesis on some related subject. I have the satisfaction of knowing I did something useful for society.

Question: What is your favourite discovery and why?

Question: Some memorable highlights and frustrations?
JC Highlights: I've touched several of the highlights. However, one of my ambitions in 1958 when I entered the field was to establish a department of medical physics in our medical school. I succeeded in 1981. I was the Chair of the first department of medical physics in a medical school in the U.S. 

Many large hospitals have physics departments to do hospital work but not for training or research in medical physics. In the last 25 years, staff in medical physics has invented many useful instruments. The royalties paid to the Wisconsin Alumni Research Foundation on their patents are now over $35 million. I am pleased that our department at UW has been so successful. I deserve a little of the credit but Dr.John Juhl, Chair of Radiology from 1966 to about 1978 was a huge help. He always supported my initiatives.

Moderate radiation to British radiologists (1955-1979) greatly reduced their death rates from non-cancer and improved their longevity by about three years - that is the increase in longevity that would occur if no one died from cancer! (It is a worthy candidate for a Nobel Prize but I can't even get the newspapers to mention it on a back page).
 

Please click here for more of the interview!
 

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Thursday, 05 February 2009