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Report from the AAPM 48th Annual Meeting
|SPS Reporter Michael Kuss (right) with Dr. Ervin Podgorsak (left), the 2006 recipient of the Coolidge Award, the highest honor awarded by the AAPM.
Do you know somebody who has been treated with radiotherapy for cancer? Have you ever had an MRI? An X-ray? If so, then you already have an idea of what a medical physicist does.
Medical physics is a specialty of physics that investigates, develops, and monitors the use of ionizing radiation for diagnosis and treatment of disease. Most notably, medical physics is largely responsible for the invention and continuing progress of radiology, nuclear medicine, and radiation therapy for cancer patients. For students with a love for physics and compassion for others, the technical challenges and opportunity for patient interaction offers a highly rewarding career.
The 2006 American Association for Physics in Medicine (AAPM) annual meeting in Orlando exhibited the most recent work of medical physicists from across North America.
As far as technical topics go, "4D" scanning and treatment was a popular topic. More traditional radiotherapy meant imaging the tumor only once (or only a few times, in some cases). The radiation treatments were then planned based on a "static" tumor, but in reality, the tumor is slowly shrinking and changing shape. The organs surrounding it are
|Exhibit Hall at the AAPM 48th Annual Meeting.
in constant motion, such as the lungs due to respiration. The problem with the "averaging" method is that much of the healthy tissue surrounding the tumor would be irradiated. Thanks to better detection equipment, tumors can be monitored using low doses of radiation in real-time. Because of the live image, radiation can be directed more precisely, and the dosage may be increased. This increase in resolution and intensity kills the tumor faster, while sparing more normal tissue.
But how does one become a medical physicist? Throughout the meeting, I had the privilege of asking several AAPM members just what being a physicist in medicine is all about.
AAPM Member Interview
Michael Kuss (MK): What can somebody do as a medical physicist?
Dr. George Sandison (George): Physicists working in the field of medicine usually concentrate on one of three things: imaging, radiation safety, and therapy. Imaging includes the support and research associated with the medical imaging modalities that include PET/CT (positron emission/computed tomography) scanners, MRIs (magnetic resonance imaging), and ultrasound. Radiation safety just means that we ensure that radioactive material is stored and handled properly, or radiation producing machines are housed, operated, and surveyed safely. Radiation therapy is almost exclusively used to kill tumors in cancer patients.
Dr. Marilyn Stovall (Marilyn): Today, radiation is used largely for the treatment of cancer. Many years ago, radiation was used to treat ulcers and other benign conditions, such as acne. Radiation therapy has fallen out of use for most benign conditions because the risk just isn’t worth the benefit for those kinds of conditions.
MK: Do medical physicists have to work in a hospital, or can they conduct more standard research in a laboratory?
George: There a few different career paths available in medical physics, one might become a full-time researcher in radiology or radiation oncology within a University setting or strictly a clinical medical physicist directly supporting the treatment of patients, for example. At a large treatment center a medical physicist may have the opportunity to become highly specialized in a particular treatment modality such as stereotactic radiosurgery or brachytherapy. Whatever path one takes it is wise to initially be broadly experienced and board certified hospital This requires that significant experience be gained in a clinical setting. Imaging knowledge and training received in medicine is readily translated to industry creating career opportunities to move in an out of medicine.
Marilyn: Typically, physicists that take the clinical route spend all of their time in the hospital working with radiologists and radiation oncologists. They regularly perform calibration and maintenance on the diagnostic and treatment devices. This may involve reviewing images that the radiologist takes of each patient, not to diagnose the patient’s condition but to verify the correct operation of the equipment. They have to ask questions like, "Is the image technically correct? Will the doctor be able to delineate a tumor?" Medical physicists are also the individuals who usually calculate radiation dosages for therapy.
MK: So, in a way, clinical medical physicists are like pharmacists, except they fill a prescription for radiation rather than medicine?
Marilyn: Yes, that is a good description of their duties.
MK: You mentioned another career path besides clinical. What else is there?
Marilyn: For students aspiring to earn their PhD and have a more traditional physics career doing research in a lab, research medical physics offers an opportunity. This would involve developing new techniques in a field where technical advances continue to improve patient care.
Dr. Ervin Podgorsak (Ervin): That is one thing unique to medical physics; to some extent, you are going to have to deal with patients, even if you are a researcher. Cancer patients are often among the most severely ill patients in the hospital, and coming from a technical field, this sort of human contact makes many new students feel ill at ease at the beginning of their medical physics career. However, like their medical colleagues, medical physicists soon get over this concern and begin to understand that they are an important part of the healing process, and that keeps many of us doing our research in hospitals.
MK: So medical physicists interact directly with patients?
Marilyn: In most cases, yes. But most of the time they work with physicians and equipment.
MK: What kinds of projects are being done in medical physics today?
George: New imaging technology is being introduced that allows us to view tumor movement in real-time and plan, optimize, and adapt therapy for dynamic conditions. We’re on the threshold of being able to treat moving lung tumors without gating the treatment to the breathing cycle or setting a static field that encompasses the movement and irradiates a lot of normal tissue surrounding the tumor. We may soon be able to correct and modify treatment on the fly to account for tumor motion under free breathing conditions. New imaging technology and agents that help us visualize and monitor tumors will also help us to target them better for eradication. We will also move beyond geometric targeting of tumors to defining their physiologic state such as proliferate activity, level of hypoxia, capability for angiogenesis, glucose use, etc. as strategies for target definition.
MK: What is your current research?
George: I have a broad research interest that I could sum up as imaging guidance and treatment of cancer using physical agents. I research in both the use of radiation and freezing of tissue to ablate tumors. However my long held interest has been in the use of charged particle radiation for cancer therapy. Most of my current effort is investigating problems associated with proton therapy. To use the previous example, in the treatment of lung tumors proton therapy has an additional level of sensitivity because the slowing of protons by different body tissues is highly variable depending upon the tissue densities encountered along their path. Organs such as the lung change density as the lungs expand and contract, so it becomes a challenging problem to treat with proton therapy under free breathing conditions.
MK: So what do you see in the future of physics in medicine?
George: Well, it’s certainly not going out of fashion anytime soon. Diagnostics and precision therapy are getting better at killing tumors and sparing healthy tissue every day. If radiation were a drug, it might arguably be labeled a "wonder drug," because it cures such a wide variety of cancers and the treatment has few side effects when applied correctly. Another advantage is that treatment is highly specific and localized rather than systemic, so there’s less effect on the rest of the normal body compared to that presently achievable with chemotherapy.
MK: So are the all-in-one, diagnosis-treatment machines from science fiction novels going to be reality in the near future?
George: In a way, they are already here. We now have integrated PET/CT machines, and can image and treat tumors almost simultaneously with Tomotherapy. That’s always been the interesting part for me personally--there’s always some new and interesting technology to invent or implement in the clinic. When I started working in this field 25 years ago, it was a dream to imagine the technology we now have at our disposal to guide therapy. I’m sure our current dreams will become a reality in another 25 years, so keep dreaming of that science fiction diagnostic-treatment machine.
MK: Is the job outlook good then?
Ervin: Most definitely. In fact, we are only training roughly half of the medical physicists that the community needs. But even though there is a shortage, the field is still highly competitive.
George: It is good but the competition is increasingly fierce. As an example, the last 63 students that applied to the AAPM Summer Undergraduate Fellowship Program had an average GPA of 3.61/4.00, and the 12 that were offered AAPM Summer Fellowships had an average GPA of 3.85/4.00. The competition is being driven by the high salaries available. An entry-level medical physicist with a master’s degree currently makes around $85,000 a year, and according to AAPM’s professional salary survey this will rise to $145,000 after about five years experience and professional certification. So the career compensation indicates there is a very good pay off to investing in your graduate education in the medical physics field.
Ervin: One reason medical physics is so competitive is because it is not like some other physics disciplines where, if an experiment fails, and you say, "Ok, let’s set this up again and get it right." Experiments and clinical treatments must be setup with extreme care and precision because you are dealing with living, breathing people. There is no flexibility. On the other hand, there is an advantage that if you choose to go the clinical route, there is not the pressure of academia where you constantly have to publish, either. There is a trade-off; it is just a different kind of pressure.
MK: So what advice would you give to an undergraduate student interested in medical physics?
Ervin: Get the best all-around physics background you can and make sure you have a solid base in modern physics as well. If you want to become a medical physicist, you need at least a master’s degree in medical physics, preferably from an accredited program. You can find information on individual programs at university websites. You can also go online to AAPM.org to find more information on medical physics as a profession. It is also recommended that you complete a 2-year residency program in medical physics, much like a medical doctor specialist must do. Unfortunately, currently there are too few medical physics residency positions available to satisfy all the need and demand.
For those looking to advance their career or do research, many folks get medical board certification, which is administered by the American Board of Radiology (ABR) or the Canadian College of Physicists in Medicine (CCPM). If you are going to do research or teach, a PhD is usually required. We hope the interesting challenges and the many rewards of being a medical physicist will attract more good students to the field.
George: We try to recruit the best and the brightest because the talented students we bring into the field are the future of our profession. We think our growing community of medical physics will continue to be a successful and rewarding field for many years to come.
Dr. George Sandison is an Associate Dean for the College of Pharmacy, Nursing, and Health Science, and he is the Head of the School of Health Sciences at Purdue University in West Lafayette, Indiana. He is also the coordinator of the AAPM Summer Undergraduate Fellowship program which is described at: http://www.aapm.org/announcements/summer_undergrad_fellow/. For more information about Purdue’s medical physics programs, visit: http://www.healthsciences.purdue.edu/
Dr. Marilyn Stovall is a professor and researcher at The University of Texas’ M. D. Anderson Cancer Center in Houston, Texas. For more information on the University of Texas’ Health Science Center, visit: http://www.uth.tmc.edu/
Dr. Ervin Podgorsak is a professor of medical physics at McGill University in Montreal, Canada, as well as a director of the medical physics unit of McGill University and the director of medical physics department at the McGill University Health Centre. Congratulation go out to Dr. Podgorsak for being the 2006 recipient of the Coolidge Award, the highest honor in the AAPM, presented to a member who has exhibited a distinguished career in medical physics, and who has exerted a significant impact on the practice of medical physics. For more information about the McGill University medical physics program, visit: http://www.medphys.mcgill.ca.
Michael Kuss is a third year undergraduate at Embry-Riddle Aeronautical University in Engineering Physics. He is also a research assistant at the Space Physics lab, as well as the president of Embry-Riddle’s SPS chapter.
For further reading on the 2006 meeting proceedings, visit: http://www.aapm.org/meetings/06AM/.
For more information on accredited medical physics programs, visit: http://www.campep.org/