Now, some local hospitals have an enhanced mammography that really improves the accuracy.
Marian Forman's family is no stranger to breast cancer.
"My mother's had it twice, one sister had it once, and her other sister had it 3 times," Forman recalls
Because of that, she's always been vigilant about getting annual mammograms.
She wasn't surprised when last year's test showed she had cancer, too.
What surprised her was the technology that found it.
Hers was one of the first tumors detected at the University of Pennsylvania using 3D mammography, also called tomosynthesis.
Dr. Emily Conant says the machine is similar to the CT scans used to find a host of internal problems.
"The machine moves in a small arc over the woman's head, taking multiple low-dose images," she says.
Then a computer assembles those individual images into a 3-dimensional one that Dr. Conant can scroll through -
Or rotate, allowing her to see breast tissue from several perspectives.
In Marian's case, the 3D mammogram, also called tomosynthesis, enabled Dr. Conant to see a very small tumor hidden behind scar tissue.
Marian notes, "This could easily have passed, easily have passed with the normal mammogram."
It also picks up suspicious tissue abnormalities which can be missed. Dr. Conant showed us one.
"This is a 6 centimeter image that is only seen on the tomosynthesis image," she says.
3D mammography boosts cancer detection, while dramatically cutting false positives.
Dr. Conant says, "We've found a reduction in our callbacks here of about a quarter - 25%."
"It's the biggest advancement in my career," she continues.
Dr. Conant says it's a very good technology for younger women with denser breasts; it's also good for a baseline mammogram, and for women wih prior surgery.
She says she is such a believer in it, "I personally waited till this was available to have my mammogram."
It's an especially touching advance for Marian.
Her father, Dr. Sylvan Eisman, established Penn's chemotherapy program 40 years ago, before oncology was even a certified medical specialty.
"He'd be ecstatic, absolutely ecstatic," she notes.
Half a dozen radiology centers in the area have 3D mammography, with more coming on line each year. Hospitals, like Penn, which have tomosynthesis, have it at their main hospital only, not satellite centers.
At Penn, there's no extra charge for tomosynthesis, if it is done as screening, however, most other hospitals or radiology centers may charge an extra fee.
Dr. Conant says a bequest from a long-time cancer patient made the purchase of the tomosynthesis machine possible. For more information on the Penn Medicine tomosynthesis program, click here.