Radiobiology in Cardiovascular Imaging

Abstract

The introduction of ionizing radiation in medicine revolutionized the diagnosis and treatment of disease and dramatically improved, and continues to improve, the quality of health care. Cardiovascular imaging and medical imaging in general are, however, associated with a range of radiobiologic effects, including, in rare instances, moderate to severe skin damage resulting from cardiac fluoroscopy. For the dose range associated with diagnostic imaging (corresponding to effective doses of the order of 10 mSv (1 rem)), the possible effects are stochastic in nature and largely theoretical. The most notable of these effects is, of course, a possible increase in cancer risk. The current review addresses radiobiology relevant to cardiovascular imaging, with particular emphasis on radiation induction of cancer including consideration of the linear non-threshold dose-response model and of alternative models such as radiation hormesis.

Computed tomography coronary angiography – past, present and future

“…Also, several societies and scientific bodies, such as the American Association of Physicists in Medicine, stated that the "risks of medical imaging at effective doses below 50 mSv for single procedures or 100 mSv for multiple procedures over short time periods are too low to be detectable and may be non-existent". (11,12) From the late 2000s to the present, further technological advancements have brought about even faster CT scanners, ranging from 640-slice dynamic volume CT scanners to thirdgeneration DSCT scanners and spectral CT. With each successive generation of CT scanners, radiation dose, contrast dose and patient turnaround time for CTCA have plummeted, while image quality has improved. This has resulted in a plethora of publications showing the promising diagnostic and prognostic value of CTCA in patients with suspected or known CAD using a relatively low radiation dose.…”

Myocardial perfusion imaging: Lessons learned and work to be done—update

“…That there is radiation exposure from nuclear imaging has never been disputed, given the fundamental basis of using low doses of radioactive tracers to gain insight into normal and abnormal cardiovascular physiology and disease processes. The concept of applying the ALARA (as low as reasonably achievable) principle is to inject the lowest radiotracer dose possible that allows the acquisition of high quality images which can be interpreted reliably without sacrificing diagnostic accuracy (36)(37)(38).…”

“…There are many ways to lower the radiation exposure including the use of stress-only imaging when applicable, newer SPECT hard-wares and soft wares, PET imaging, and more importantly appropriate utilization. A recent paper provided a thorough analysis and modeling of the radiation risks (38). It is understood that no discussion on risk is complete without acknowledging the tremendous contributions of nuclear cardiology imaging to patient management which explains why despite all new developments it remains the most popular non-invasive stress test.…”

Low-dose radiation cancer risk hypothesis may lead to ‘radiophobia’-driven imaging avoidance?

“…1 However, the assessment of risk, associated with the performance of low-dose diagnostic cardiovascular procedures (significantly lower than 100 mSv), is based on data that refer to much higher doses, using mathematical extrapolation models. 2 Interestingly, it should be noted that a proposed model (the hormesis model) implies lower subsequent cancer risk in individuals exposed to low doses. 2 Despite the inconclusive evidence regarding the potential adverse effects in the low-dose burden of nuclear cardiology procedures, we often face strong concerns over the radiation safety during our clinical routine.…”

“…2 Interestingly, it should be noted that a proposed model (the hormesis model) implies lower subsequent cancer risk in individuals exposed to low doses. 2 Despite the inconclusive evidence regarding the potential adverse effects in the low-dose burden of nuclear cardiology procedures, we often face strong concerns over the radiation safety during our clinical routine. Commonly, patients and their relatives are troubled for the radiation-induced health consequences, and in particular the possibility of induced cancer risk.…”