Precision is the professional credo of medical dosimetrists, a little-known but growing group of healthcare workers who calculate radiation doses and develop complex treatment plans to destroy patients' cancerous tumors.
"We really have to limit our mistakes to none," says Mark Reid, senior dosimetrist at Fletcher Allen Health Care in Burlington, Vermont, and president of the American Association of Medical Dosimetrists (AAMD). "The consequences of what we do can have a huge impact on the patient in the long run."
Medical dosimetry is still in its infancy, Reid says, and there are only a few thousand dosimetrists in the US. However, more, earlier cancer diagnoses mean demand is growing for all professionals involved in providing radiation therapy, including dosimetrists.
Delicate Balancing Act
Reid spends his days generating radiation treatment plans via computer and reviewing patient cases with radiation oncologists, oncology nurses, medical physicists and radiation therapists. Once or twice a week, he accompanies patients to CT diagnostic scans, which serve as the basis for his calculations and dose distributions. Because he makes frequent patient contact, Reid says he "can't be just a physics nerd. You need some sensibilities about what is going on with patients. You use a lot of different skills to do your job."
Dosimetrists craft their treatment plans using sophisticated 3-D computers that enable them to give higher doses of radiation to a tumor and lower doses to sensitive structures nearby. One of the job's trickiest aspects is maintaining the delicate balance between delivering the radiation dose prescribed by the oncologist while ensuring healthy organs aren't affected, says Juan Peña, senior medical dosimetrist at the University of Texas Medical Branch in Galveston.
Another challenge of the job is accepting that there is no "magic bullet" for curing cancer patients, Peña says. "We sometimes have to acknowledge the limits of the profession," he explains. "Despite our advanced medical technologies, we are limited in what we have available and what we can do."
Body of Knowledge
Like most medical dosimetrists, Peña started his career as a radiation therapist, aka radiation therapy technologist. He was recruited and trained for the dosimetry job by a medical physicist at his facility. Medical dosimetrists who do not start out as radiation therapists may be graduates of one of the handful of one- to two-year dosimetry programs across the country. Another way to enter the profession is by earning a bachelor's degree in physics and completing extensive on-the-job training.
Dosimetrists must be critical thinkers capable of working with mathematical formulas, according to Peña. They must also be willing to learn new technologies. "This field is constantly evolving," he says. "We are always getting new types of treatment modalities."
Dosimetrists must also have knowledge of anatomy, physiology and oncology, Reid says. "You need to know the natural history of tumors -- where and how they spread -- and how that will influence the treatment plan," he explains.
Although the field requires a considerable amount of specialized knowledge, medical dosimetrists do not have to be licensed or certified. However, Congress is currently considering an AAMD-supported bill that would set minimum educational requirements for those in the radiation-therapy professions, including medical dosimetry. In the meantime, many medical dosimetrists voluntarily become certified through the Medical Dosimetrist Certification Board.
The demand for medical dosimetrists grows every time a new cancer center opens, Reid says, making dosimetry a stable, well-compensated career. Medical dosimetrists earn average annual salaries of $79,500, according to a 2004 AAMD salary survey.
However, the few medical-dosimetry education programs in the US graduate only 12 to 15 students a year, while 78 to 80 new dosimetry positions become available in the country annually, Reid notes. The AAMD is encouraging more universities to offer dosimetry degrees, he explains, but it's a hard sell, because the number of students who enroll is often too small to justify the resources necessary to run a program. "It's a real daunting task to try to increase the number of trained dosimetrists," he says.