BOSTON -- For Helen Loulache the end of treatment for breast cancer marked the beginning of a new battle.

This wife and mother endured surgery and seven weeks of radiation only to get slammed with a $43,000 dollar bill.

"I don't feel it's my fault," she said. "I had proper insurance. My coverage booklet says it includes 100 percent of radiation."

But apparently not for the type of radiation she received at the Caritas Foxboro Center. A technique called IMRT costs twice as much as standard radiation.

"We do offer this treatment to many of our patients with good results, and that's why the decision was made for this patient," said Tim Arnold, of the Caritas Cancer Care Program.

But Loulache's out-of-state insurer, Excellus BlueCross BlueShield of Rochester, New York, denied the claim calling IMRT experimental for breast cancer. On appeal three independent oncologists found IMRT was not more beneficial than standard treatment and said the denial should be upheld.

"I'm of the mind the insurance company is responsible for this," said Caritas' Arnold. "The treatment has been around for almost 10 years."

In an e-mail, Jim Redmond, a regional vice president for Excellus, said he could not comment on a specific member's case. But he added, "Our contracts exclude coverage of experimental treatments because they are not proven through clinical trials and peer-reviewed medical literature to be safe or effective."

The president of the Massachusetts Medical Society tells Team 5 Investigates this case points to a major problem.

"There isn't a bright line between what constitutes research and what constitutes advanced care. We really need that," said Dr. Dale Magee. "We don't have the same oversight with procedures and techniques that we do with drugs and devices."

Health care advocates say this is not an isolated case. Many patients get stuck in the middle between hospitals and their insurance companies

"It's grossly unfair for the consumer to be hit with this bill," said Barbara Anthony of Health Law Advocates. "The consumer is an innocent bystander here. She had no way of knowing this was not covered by her insurance policy."

Advocates say if possible, patients should call their insurance company before a major treatment.

"Talk to someone, take a name, record the date and time because the insurance company is recording and that will be important later on if insurance company says it's not covered," said Anthony.

Caritas says it's working with the patient to try to find alternative funding to cover her bill.

"I feel this is something that should go on between the hospital and the insurance company, not me," said Loulache. "I'm kind of an innocent bystander who got caught in the middle."