Once limited to bulky equipment and rays of energy, radiology has expanded in the digital age -- and so have its specialties. From positions as cardiovascular interventional technologists to sonographers and mammographers, opportunities in radiologic technology are growing.

Indeed, the US Bureau of Labor Statistics predicts faster-than-average job growth for radiology professionals through 2016. Radiologic technologists in various specialties are working in physicians' offices, diagnostic imaging centers, outpatient care centers, and medical and diagnostic laboratories across the country.

While demand for radiographers is strong across the board, certain specialists are more desired than others. Experts say mammographers, ultrasound technologists (also known as sonographers), nuclear medicine technologists and cardiovascular interventional technologists are the most-coveted specialists in a profession with an overall vacancy rate of 4.5 percent, according to a survey conducted by the American Society of Radiologic Technologists (ASRT).

Mammography: The Forgotten Specialty

Mammographers use radiation to produce images to screen for or diagnose breast disease. They must have special certification beyond general radiology to practice.

Mammography's ranking as one of the lowest-paying radiology specialties could be a factor in its severe labor shortage. The mean annual salary for a mammographer is about $56,600, according to the ASRT's 2007 Wage and Salary Survey. By comparison, nuclear medicine technologists earn about $69,100 a year.

The Government Accountability Office reported a drop in the number of first-time examinees for mammography certificates. The agency forecasts that a predicted decrease in mammographers could lead to longer wait times for appointments at a time when women are being urged to have regular screenings.

"So many X-ray technologists today want to jump right into CT (computed tomography) and MRI (magnetic resonance imaging), because they pay more and use the latest and greatest technology," says Cathy Parsons, president-elect of the ASRT. "Mammography is often overlooked or forgotten."

The Hottest Specialties

Specialists in three other areas -- nuclear medicine, sonography and interventional -- are also in high demand.

Nuclear medicine technologists administer radioactive materials to produce images that help diagnose and treat various disorders. Parsons says the relative lack of educational programs in this area, coupled with the fact that physicians are relying more on the data these technologists provide to reach a diagnosis, are factors fueling demand.

However, the pressure-cooker nature of nuclear medicine leads fewer technologists to choose it as a specialty, explains Jim Sutton, director of radiology at the Mayo Clinic in Rochester, Minnesota.

"Nuclear medicine is in higher demand, because it is a regulated area," he says. "Besides radiation therapy, nuclear medicine is the most mentally taxing, because there are so many mathematical formulas involved.

Sonographers and interventional technologists are also in high demand, but for different reasons, says Patricia Clark, manager of performance improvement and quality assurance for Temple University Hospital's radiology department.

"Due to the workload in ultrasound and interventional technology spurred by new studies, equipment and procedures, the demand is rising in these areas," Clark says.

Radiographers are flocking to ultrasound, where mean annual salaries exceed $63,000, according to the ASRT salary study. Clark says fewer are going into interventional technology. Specialists in this area are required to be on call, a quality-of-life factor that could be keeping some radiologic technologists away.

Nuclear medicine and ultrasound both require additional certification. Interventional technologists can practice with a general radiology certification.

General Radiology: Hurting for Help

With so many appealing specialties, fewer graduates are going into general radiology, a trend Parsons says is a real concern.

"There's a big shortage in X-ray," she says. "Everyone is going into these other specialties, and that leaves us in a bad position. My advice to every new graduate is to work in X-ray for a couple of years before you decide on a specialty. It's good for you, and it's good for the industry."