por Loren Bonner
, DOTmed News Online Editor | January 06, 2014
Nuclear cardiologists are under immense pressure these days to reduce radiation dose. In reaction to mounting evidence of inappropriate overutilization of myocardial perfusion imaging over the years, the American Society of Nuclear Cardiology has responded with guidelines, which are effective Jan. 1, 2014, to reduce dose. And they offer three specific ways it can be achieved. DOTmed News spoke with Dr. E. Gordon DePuey, director of nuclear medicine at St. Luke's-Roosevelt Hospital in New York City, about these recommendations.
DMN: Why is the field of nuclear medicine, and specifically nuclear cardiology, under pressure to reduce radiation dose?
The radiation dose that is afforded to patients with a standard myocardial perfusion SPECT scan is relatively high compared to other radiography modalities. With a standard protocol we are affording patients approximately 11 millisieverts of radiation exposure. Also, compared with other nuclear medicine procedures the dose is relatively high. Nevertheless, any harm from this degree of radiation is still very theoretical. Although there have been no hard data to suggest there's an increased risk of cancer due to this degree of radiation, from a theoretical standpoint, there might be a very, very slight increase. The medical community, the public, and the media are well aware of this small, theoretical risk. So specialists in nuclear cardiology, as well as all of nuclear medicine and radiology, are under pressure to decrease radiation dose.
DMN: Tell me about the new 2014 ASNC guidelines that are intended to reduce dose in nuclear cardiology procedures?
These guidelines have been published by ASNC [The American Society of Nuclear Cardiology]. By 2014, 50 percent of patients undergoing myocardial perfusion imaging should have a radiation dose of less than 9 millisieverts. That is somewhat lower than the 11 millisieverts associated with the most commonly used myocardial perfusion SPECT protocol. Of note, there are other protocols in nuclear cardiology that actually give higher doses than 11 millisieverts. First, the ASNC guidelines try to eliminate — or at least minimize — these other protocols that afford a higher radiation dose. Second, there is a move to perform stress-only imaging, where only the stress part of the test is performed. Generally, you need both the stress and resting parts of the test, but if you chose your patients carefully, and have rigorous technology quality control, you can perform the stress-only part of the study, thereby decreasing patient radiation dose to about half, well below the 9 millisievert guideline. However, to do stress-only imaging well, you really need attenuation correction. Unfortunately only a few nuclear cardiology labs have attenuation correction, so implementation of stress-only imaging is not so easy.