Invasive fluoroscopy

Diagnostic and interventional fluoroscopy procedures represent the largest source of radiation exposure in cardiology (Figure 1).

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Figure 1. Doses of common cardiology examinations expressed in mSv (left Y-axis) and in equivalents of chest X-ray (right Y-axis). 1 mSv = 50 CXRs; 1 CXR = 0.02 mSv. AF: atrial fibrillation; CMR: cardiovascular magnetic resonance; CCTA: coronary computed tomography angiography; ETAAAR: endovascular thoracoabdominal aortic aneurysm repair; FDG-PET: fluorodeoxyglucose-positron emission tomography; PCI: percutaneous coronary intervention; SPECT: single-photon emission computed tomography.

Reference doses vary widely due to numerous factors, including patient habitus, procedure complexity, operator experience, and equipment characteristics. Diagnostic coronary angiography typically delivers approximately 7 mSv (equivalent to 350 CXRs), while percutaneous coronary interventions (PCIs) average 15 mSv (750 CXRs) [4, 5]. Complex interventions such as chronic total occlusion dilation can reach 81 mSv (4,050 CXRs), and aortic aneurysm repair procedures range from 76–119 mSv (3,800–5,950 CXRs) [6, 7]. The radiation dose is reported as median and interquartile range (Table 1).

Cardiac electrophysiology

Electrophysiology procedures contribute substantially to both patient and operator exposure. Diagnostic electrophysiology studies average 3.2 mSv (160 CXRs), while ablation procedures—particularly for atrial fibrillation—deliver approximately 16.6 mSv (830 CXRs) [6, 7]. Cardiac resynchronization therapy implantation involves about 22 mSv (1,100 CXRs), reflecting the complexity of these interventions [4, 5]. The radiation dose is reported as median and interquartile range (Table 1).

Computed tomography

Coronary computed tomography angiography (CCTA) has emerged as a significant source of medical radiation, with current protocols delivering approximately 7.4 mSv (370 CXRs) and new technology reaching < 3 mSv [4, 5]. Coronary artery calcium scoring (CACS), while lower at 1.2 mSv (60 CXRs), remains significant when considering its frequent use in asymptomatic populations. However, technological advances have enabled dramatic dose reductions, with modern scanners achieving up to 95% reduction compared to reference doses [8]. The radiation dose is reported as median and interquartile range (Table 1).

Nuclear cardiology

Nuclear cardiology procedures demonstrate considerable dose variability depending on tracer selection and protocol. Traditional thallium-201 stress-rest single‑photon emission computed tomography (SPECT) studies deliver 40.7 mSv (2,035 CXRs), while contemporary technetium-99m-based protocols range from 3.9 to 8.6 mSv (195–430 CXRs) [4, 5]. Positron emission tomography (PET) offers lower doses, with ammonia-13 stress-rest protocols averaging 2.0 mSv (100 CXRs) [8]. The American Society of Nuclear Cardiology has prioritized dose reduction, establishing as a primary goal that 50% of examinations should achieve < 10 mSv exposure [4, 5]. The radiation dose is reported as median and interquartile range (Table 1).

Pediatric considerations

Children show greater radiosensitivity than adults, making pediatric radiation exposure particularly consequential [6]. The radiation dose is reported as median (Table 2) and has been dramatically reduced in the last 10 years [6]. The updated estimates for common invasive pediatric cardiology examinations show a constant downward trend in all examinations in all institutions, due to technological advances in imaging systems, growing awareness of the long-term effects of radiation exposure in pediatric populations, and adoption of radiation-sparing technology by operators, for instance, with decreasing use of image quantification and reduction of frame rate during fluorography acquisition [6].

The 2020 American College of Cardiology/American Heart Association guidelines explicitly acknowledge that radiation exposure remains a critical consideration for congenital heart disease patients requiring serial imaging over a lifetime [7].

Individual risk

The relationship between radiation dose and cancer risk follows a stochastic model: increasing dose increases the probability, not severity, of malignancy. Cumulative exposure in cardiology patients can be substantial, with one in five adults and children with congenital heart disease exceeding 100 mSv lifetime exposure—equivalent to 5,000 CXRs and corresponding to approximately one excess cancer per 100 exposed individuals [9–12]. Recent data have reaffirmed the linear no-threshold model even below the 50 mSv threshold, and the cancer risk tends to be higher than previously assumed, exactly in the low-dose, low-dose rate range, where DNA damage is more frequently sublethal and therefore more often transmissible to subsequent generations of cells [13].

Risk varies significantly by age, sex, and genetic factors. Children face a fourfold higher risk than adults for equivalent doses. Women demonstrate 38% greater vulnerability than men, particularly due to highly radiosensitive organs such as the breast [13]. A 35-year-old woman undergoing a thallium scan faces cancer risk as high as 1 in 300, compared to approximately 1 in 1,000 for a middle-aged man undergoing myocardial perfusion imaging.

Specific malignancies reflect organ-specific dosing. Invasive cardiology procedures predominantly expose bone marrow, lungs, stomach, and thyroid, while nuclear cardiology delivers the highest doses to colon, bone, and bladder [2, 4, 5, 12, 13]. Chromosomal aberrations—reliable intermediate biomarkers for cancer—increase acutely after fluoroscopy procedures and persist decades after exposure in both patients and interventional cardiologists [11, 14].

Population risk

The population burden of medical radiation-induced cancer is substantial. Approximately 9 million myocardial perfusion imaging scans performed in 2006 in the United States translate into roughly 8,000 additional lifetime cancers [15]. Computed tomography utilization in 2023 was estimated to contribute 5% of all US cancers [16]. Global estimates suggest medical radiation may account for 5–10% of all cancers when using updated exposure assessments [17–19].

The ISCHEMIA trial [20] showed that the risk of malignancy deaths increased linearly with the number of exposures to ionizing testing, such as coronary CT, myocardial perfusion scintigraphy, invasive coronary angiography, and PCI. Compared to patients with 1 radiation exposure, the risk increased 2-fold in patients with 2 radiation exposures and 4-fold in patients with 3 radiation exposures, with a median follow-up time of 3.2 years in a population of patients with chronic coronary syndromes.

Research involving patients with congenital heart disease indicates a greater risk of cancer in children who undergo more than six radiation-based procedures at a young age. The highest radiation exposure to specific organs—along with the associated predicted cancer risk—has been observed in the thyroid gland and female breast tissue [21].

Non-cancer radiation risks

Emerging evidence implicates radiation exposure and cardiovascular disease, with risk magnitude potentially comparable to cancer [22]. This association extends beyond the high-dose radiotherapy setting to include cumulative diagnostic exposures in the low-dose range, below 100 mSv [23]. Shared biological mechanisms include DNA instability, chronic low-grade inflammation, and increased oxidative stress [23].

Occupational studies demonstrate increased subclinical carotid atherosclerosis and premature vascular aging in interventional cardiologists with long-term radiation exposure [3]. These findings align with observations from atomic bomb survivors and radiation workers, suggesting that vascular effects represent a genuine stochastic risk of low-dose exposure rather than a threshold phenomenon [19].

Cardiologist risk

Interventional cardiologists face professional exposures 4–5 times higher than diagnostic radiologists, approaching levels observed in early radiation workers and contemporary astronauts [24]. Documented health effects include increased chromosomal aberrations in circulating lymphocytes, elevated rates of left-sided brain tumors (ipsilateral to higher dose received from typical X-ray tube positioning), and multiple cutaneous malignancies in unprotected skin areas. Population-based studies demonstrate increased cancer risk among cardiologists who frequently perform PCI [24].

Sonographer exposure

Cardiac sonographers face two distinct radiation exposure sources: patient-emitted radiation following nuclear imaging and scatter radiation in interventional laboratories. Patients injected with radiotracers become “hot” sources; at 90 minutes post-technetium-99m administration, chest wall dose equivalents measure 0.37–0.58 mSv. A 24-minute echocardiogram can deliver up to 0.16 mSv to sonographers, with higher exposure during left-handed scanning. Transport workers face approximately 0.02 mSv during 10-minute patient transfers [25].

Protective apparel offers limited benefit against high-energy photons emitted by radioisotopes. Lead aprons block 90% of X-rays but prove ineffective against positron-emitting tracers (fluorine-18, nitrogen-13), modestly effective against technetium-99m, and effective only against low-energy thallium-201 photons. Optimal protection involves temporal separation: 24 hours for PET or technetium studies, one week for Thallium examinations [5, 25–27].

Evolution of radiation awareness

The 2005 American College of Cardiology/American Heart Association clinical competence statement established that “the responsibility of all physicians is to minimize the radiation injury hazard to their patients, to their professional staff, and themselves” [27]. The 2009 American Heart Association position paper identified “Top-10 things to know about ionizing radiation in cardiac imaging,” emphasizing that studies using radiation should be ordered only after thoughtful consideration of potential benefits and consistent with appropriateness criteria [28].

Achieving radiologic sustainability

Conclusion

No doubt ionizing radiation gives an immense benefit to diagnosis and therapy in modern cardiology. Although cardiologists cannot be scared of ionizing radiation, they must be scared of radiation negligence and always consider radiation in the risk side of the risk-benefit assessment of every diagnostic or therapeutic procedure, especially when discretionary or repeated imaging is performed, where alternatives exist.

Radiation exposure in cardiac imaging represents a clinically significant and often modifiable risk factor for cancer and accelerated atherosclerosis. The cumulative burden in cardiology patients frequently reaches levels associated with measurable population harm, while occupational exposures place healthcare workers at increased risk. Guideline recommendations have evolved to emphasize justification, optimization, and education as essential components of quality cardiovascular care. Technological advances enable substantial dose reduction, and non-ionizing alternatives offer effective diagnostic options without carcinogenic risk. A radiation-aware practice protects patients, staff, and practitioners while enhancing the overall sustainability of cardiovascular medicine. Action needs to be taken to reinforce the culture of radiation through appropriate changes in medical school and cardiology fellowship curricula, prepare transparent informed consent forms before the incorporation of dose in the written report, and adopt conservative approaches for human research and scientific publication to always justify the applications of radiation doses.

The basic idea is straightforward: if you can avoid taking a dose entirely, that’s the best option, both for patients and for intensively exposed doctors, like invasive cardiologists and electrophysiologists. No dose is the best dose.