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HappyPoet wrote:There are a couple old threads here that discuss how one session of CT venography is equal to the exposure of approximately 100 X-rays. Sorry.

DrSclafani wrote:the dose of an angiogram of the neck and chest generates about 5 millisievert, (mSy) which is a definition of dose absorbed.

Lets put that in perspective. The dose is about the same as 170 chest xrays. A head CT scan is 2 mSy, a chest CT 8mSy. Annual allowable occupation dose limit is 50 mSy. the LD50 is 5000 Sy.

NHE wrote:

HappyPoet wrote:There are a couple old threads here that discuss how one session of CT venography is equal to the exposure of approximately 100 X-rays. Sorry.

Here's Dr. Sclafani's post...

http://www.thisisms.com/ftopicp-113211.html#113211

DrSclafani wrote:the dose of an angiogram of the neck and chest generates about 5 millisievert, (mSy) which is a definition of dose absorbed.

Lets put that in perspective. The dose is about the same as 170 chest xrays. A head CT scan is 2 mSy, a chest CT 8mSy. Annual allowable occupation dose limit is 50 mSy. the LD50 is 5000 Sy.

NHE

Heart attack survivors who undergo scans and nuclear medicine tests tend to have higher rates of cancer than those with less exposure, a new Canadian study suggests.

The researchers, from the McGill University Health Centre and the Jewish General Hospital in Montreal, note that the use of cardiac imaging tests has exploded in recent years in both Canada and the U.S.

And yet, they point out, little attention has been paid to the cumulative effect of the radiation used in those tests, or on how they might be affecting cancer rates.

So for this study, which appears in the Canadian Medical Association Journal, the researchers looked almost 83,000 patients who had a heart attack between 1996 and 2006, but who had no history of cancer.

About 77 per cent underwent at least one cardiac procedure using low-dose ionizing radiation within a year of the attack.

The tests included a heart imaging test called myocardial perfusion imaging, angiogram procedures called diagnostic cardiac catheterization and percutaneous coronary intervention, as well as a form of nuclear imaging called cardiac resting ventriculography All the tests involve exposing patients to low-dose ionizing radiation.

While most patients received only a low or moderate level of radiation, a substantial group were exposed to high levels through repeated tests -- and these patients tended to be younger, healthy men.

The study's lead author, Dr. Louise Pilote, a researcher in epidemiology, says her team found a distinct link between the cumulative exposure to low-dose ionizing radiation from cardiac imaging and the risk of cancer.

Over the course of the study, the researchers found 12,000 incidents of cancers, with two-thirds of the cancers affecting the abdomen/pelvis and chest areas.

They calculated that for every 10 "milliSieverts" of ionizing radiation, there was a 3.0 per cent increase in the risk of cancer, the study found. (A milliSievert is commonly used to measure the radiation dose in diagnostic medical procedures.)

Since the risk for cancer grows with age, the researchers accounted for that in their calculations.

"These results call into question whether our current enthusiasm for imaging and therapeutic procedures after acute myocardial infarction should be tempered," she and her co-authors conclude.

sou wrote:So does immune suppression.