No question about it – CT scans are fabulous technology and have saved lives. But there are also concerns that the radiation from a CT scan could increase your risk of getting cancer.

A new study by the Orlando Regional Medical Center set out to determine how much radiation people are being exposed to. To figure this out, they looked at a randomly selected group of emergency room patients, and determined how much radiation they’d been exposed to through CT scans and other tests. The researchers found that on average, the patients over a five-year period had accumulated 40 mSv (millieseiverts are a unit of radiation measurement). Twelve percent were estimated to have received 100 or more mSv of radiation. To put that in perspective, the average chest X-ray gives you .02 mSv of radiation.

So does this mean these patients were destined to get cancer? Absolutely not. A CT scan increases your risk of getting cancer, but by “a very small amount,” says David Brenner, professor of radiation oncology and public health at Columbia University Medical Center. His bottom line: If you need a CT scan, by all means get one. But when your doctor recommends a CT scan, ask questions to make sure you really need it. Brenner suggests asking these questions:

1. Is there an alternative to a CT scan?
Brenner says sometimes doctors can do other tests, such as an ultrasound, which doesn’t involve radiation. Or sometimes no test at all – just waiting to see what happens – is an alternative, says Dr. Timothy Bullard, the lead author of the Orlando study.

2. Have I had this CT scan somewhere else?
Brenner says doctors sometimes order a CT scan even when the exact same test was done by another doctor – but it would take a lot of time and effort to get that scan. Since getting scans from one doctor’s office to another can be the equivalent of moving a medical mountain, Brenner has this suggestion: Ask to have the scan put on a thumb drive or a disc to keep for yourself and share with your future doctors.

3. Is my child getting a pediatric dose of radiation?
Brenner says too often children get an adult-size dose of radiation. “It’s better than it used to be, but it still happens,” he says.

For more tips on becoming an Empowered Patient, check out my column at CNN.com/empoweredpatient

Tim Russert’s death last week from a heart attack left viewers of “Meet the Press” devastated – and full of questions. Russert was only 58 and didn’t look ill. How could he have a heart attack?

The reality is that all too often heart attacks sneak up on their victims. “Most heart attacks start slowly, with mild pain or discomfort,” according to the American Heart Association. “Often people affected aren’t sure what’s wrong and wait too long before getting help.”

The American Heart Association says to look out for these signs of a heart attack:

1. Chest discomfort - The pain usually last more than for a few minutes, and it can go away and come back. Some people describe it as uncomfortable pressure, squeezing, fullness, or pain.

2. Discomfort in other areas of the upper body – Pain in one or both arms, the back, neck, jaw, or stomach can be a sign a heart attack is happening.

3. Shortness of breath – It may occur with or without chest discomfort.

Women’s heart attack signs may be different from men’s. Women, who tend to have heart attacks 10 years later than men, are somewhat more likely to experience nausea, vomiting, back, and jaw pain, according to the National Institutes of Health.

Would you know what to do if you or someone else had a heart attack? Take this quiz from the NIH and find out. You can also click here to listen to heart attack survivors talk about their experiences.

Quiz:  http://www.nhlbi.nih.gov/actintime/taha/quiz.htm

Survivors:  http://www.nhlbi.nih.gov/actintime/haws/haws.htm