BOSTON -- Mammograms are an important way of detecting breast cancer, but they are not fail-proof.

NewsCenter 5's Liz Brunner reported that one in five mammograms is a false negative, showing no breast cancer when in fact the cancer exists.

Now a new, nuclear technology being used at the Lahey Clinic is helping to improve breast cancer diagnosis.

Last spring, Ines Fusco, 43, found a 2 ½-inch lump in her breast.

"I was in the shower and I was bathing and I said, 'Oh gee, what the heck is that?'" she said.

Both a mammogram and an ultrasound showed nothing.

"And the radiologist said, 'Everything is negative. You have nothing to worry about, Mrs. Fusco,'" she said.

But Dr. Stephen Karp at Lahey Clinic wanted to check further. He gave Fusco a new type of imaging test called scintimammography and the test came back positive.

"The imaging clearly showed a hot spot right at the sight of the palpable mass, and that helped us confirm our decision," Karp said.

Scintimammography involves a small amount of radioactive dye injected into the patient's veins, and then the breast is viewed through a high-resolution camera.

"When you're looking at a scintimammogram, the normal breast tissue doesn't pick up the radioactive material whereas abnormal tissue does," said Dr. Anna Chacko, radiology chair at the Lahey Clinic.

Lahey Clinic is the first hospital in Massachusetts to use scintimammography on patients with inconclusive mammograms.

"We're finding it immensely helpful, particularly in younger patients who have very dense breasts," said Chacko.

Fusco has undergone two surgeries and is about to have her third. Without the scintimammography, she said she might not even know the cancer existed.

"I feel very lucky. I have two children and a wonderful husband and I expect to be around for a long time," she said.

Doctors said the scintimammogram is also less painful than a traditional mammogram because it does not flatten the breast. Doctors claim the radioactive dye used in the scintimammogram is safe and is expelled by the body within 24 hours.