HHN: New research from Stanford University’s Cardiovascular Institute found that "exposure to small amounts of radiation from [CT] scanning is associated with cellular damage." Examining the blood of 67 people before and after having a heart CT scan, researchers discovered increased DNA damage in cells, cell death, and increased expression of genes involved in the repair or death of cells. Whereas most cells damaged by the CT scan were repaired, a small percentage died. Senior author Dr. Joseph Wu acknowledged that "these tests expose patients to a non-trivial amount of low-dose radiation," equivalent to at least 150 times the amount of radiation from a single chest X-ray. While the study didn’t find any DNA damage in healthy people of average weight who had the lowest radiation doses, study co-lead author Dr. Patricia Nguyen said "the findings should encourage physicians to use CT scan dose-reduction strategies." Given these findings, should we be concerned about the potential dangers of the Coronary Artery Calcium Scoring test you recommended to ascertain the state of our hearts?
JK: The Stanford data is not suprising. Radiation, whether from airplane travel, living at high altitude, medical imaging, or sunshine, can all damage DNA.
The importance of the Stanford data is the details: No DNA damage was seen when the dose of radiation was less than 7.5 milliSieverts (mSv). Looking at the different kinds of testing cardiologists do:
- A typical stress nuclear study (thalllium or Cardiolite injection) may expose a patient to 15 mSv.
- A typical cardiac catheterization exposes to a patient to around 8 mSv, but it can be much higher if angioplasty and stenting is performed.
- A CT angiogram of the heart arteries is routinely done for under 5 msv.
- A simple Coronary Artery Calcium Scoring without contrast is about 1 mSv.
Therefore, it is reassuring that no DNA damage can be expected when ordering Coronary Calcium CT scoring or most CT angiograms on patients. In addition, prior data suggests that having a radiation procedure following an antioxidant-rich meal or vitamin packet may further lower DNA damage.