Picano et al. BMC Cancer 2012, 12:157 http://www.biomedcentral.com/1471-2407/12/157 Page 10 of 13 Figure 6 Scatter dose rate values during fluoroscopy in interventional cardiologists without protection (as is was standard practice in many laboratories until some years ago). The use of lead cap protection or total body protection with radioprotection cabin or ceiling suspended screen reduces the scatter dose to less than 1%. From the International Atomic Energy Agency collection of slides (Radiation Protection of Patients, on the dedicated and continuously updated website: http://rpop.iaea.org.website), ref 96 (Kuon 2003) and ref. 18 (Dragusin, 2007). 500 unexposed controls (clinical cardiologists and nurses). With this limited sample size, the detection of potentially increased health risks remains difficult using the epi- demiological approach. Therefore, as an alternative to the epidemiological approach, the Healthy Cath Lab study will assess brain effects though “early warning signs”, which evaluate initial damage through surrogate endpoints that are easy to measure, non-invasive, and able to identify long-term risk for subsequent clinically overt disease. Other effects evaluated in the study are endocrine, repro- ductive, and atherosclerotic functions. Examples of surro- gate end-points adopted in the study are carotid-intima media thickness for cerebrovascular atherosclerotic disease [99], olfactory dysfunction for neurodegenerative disorders [100], and circulating plasma brain-derived neurotrophin, which is directly linked to hippocampal neurogenesis and is reduced in pre-depressive and neurodegenerative condi- tions [101]. Both the North American and Italian studies will bring the safety issue center stage and are destined to increase awareness of ionizing radiation in the catheterization laboratory and generate relevant data for better understanding of the most serious health effects of professional chronic low-dose radiation exposure, eventu- ally bridging the experimental and epidemiological divide between high-dose (radiotherapy) and chronic low- to moderate doses (professional exposure) [102]. Taken to- gether, these studies should remind the interventional car- diology community that “the responsibility of all physicians is to minimize the radiation injury hazard to their patients, to their professional staff and to themselves” [103]. Conclusions The brain is among the most critical dose-limiting organs in radio-therapy, mainly due to the development of cognitive dysfunction following white matter disrup- tion. The neuro-vascular unit is also vulnerable to radi- ation effects, and cerebro-vascular atherosclerotic Table 3 Ongoing studies on interventional cardiologists Main funding NIH and NCI Scientific Societies endorsement Multispecialty Occupational Health Group Enrolled population Endpoint 44,000 fluoroscopists (interventional cardiologists, radiologists, neuroradiologists) 42,000 non-interventional radiologists 101,000 non-exposed physicians Epidemiological clinical endpoints (cancer, cataract, vascular events) Surrogate biomarkers of genetic, vascular, reproductive, cognitive effect Italian CNR National Research Council-IFC, Institute of Clinical Physiology Italian Society of Invasive Cardiology (GISE) 500 exposed interventional cardiologists (nurses, technicians) 500 non exposed clinical cardiologists (nurses, technicians)