Radiation Exposure, Training, and Safety in Cardiology

Exposure to ionizing radiation is an inherent occupational health hazard in clinical cardiology. Health risks have been reported previously, including predilection to cancer. In addition, orthopedic injury due to prolonged wearing of heavy protective lead aprons, which are mandatory to reduce radiation risk, have been extensively documented. Cardiology as a specialty has grown with rising volumes of increasingly complex procedures. This includes electrophysiological, coronary, and structural intervention, advanced heart failure/transplant management, and diagnostic imaging. Both the operator as well imaging specialists are exposed to radiation, particularly in structural interventions where interventional cardiologists and structural imagers work closely. Increasingly, women interested in cardiology may deselect the field due to radiation concerns. This expert document highlights the risks of radiation exposure in cardiology, including practical tips within various subspecialty fields such as interventional/structural cardiology, electrophysiology, imaging, advanced heart failure, and pediatric cardiology.

reasons for sex disparities in invasive cardiology. 10Women who do choose an invasive cardiology subspecialty may need to factor in risks of radiation exposure alongside family planning.
[13] In this expert review, we will discuss the radiation risks inherent in interventional/ structural cardiology, electrophysiology, imaging, advanced heart failure (AHF), and pediatric cardiology and provide practical recommendations for minimizing radiation exposure.Relevant terms used throughout this paper are defined in Table 1.

CORONARY/STRUCTURAL CARDIOLOGY
Radiation exposure during these procedures is substantial, especially in complex percutaneous coronary interventions (PCI) and structural interventions. 14creased awareness and advances in protective measures have improved the response to radiation exposure.The PROTECTION VIII study, which included 3.7 million PCI procedures between 2008 and 2018 15 showed that, over this period, radiation exposure was reduced by 36%.
Several factors are important when considering radiation exposure to the operator.The most important factor is patient body mass index (BMI), which independently increases operator radiation dose by approximately 5% per unit increase in BMI. 16With respect to equipment, older generation x-ray machines may not have the necessary quantum detection efficiency and calibration to reduce exposure with higher radiation doses.Operator behavior is a modifiable factor and includes appropriate image field definition and collimation, reduction in the frame rate, limited cine loop acquisition, compliance with protective measures and monitoring requirements, and maintaining maximal distance from the image intensifier.
All cath labs should have a ceiling-mounted, movable upper-body shield and lower-body shield mounted on the side of the patient table; these reduce scatter radiation by approximately 80% to 90%. 17 There is variation in the effective use of these protection devices.9][20] Sciahbasi et al 21 noted in their phantom simulation of diagnostic coronary angiography (DCoA) that operators had lower exposure at the wrist and thorax, higher radiation at hip level, and no difference at the head level when using left radial access.Another study detected similar radiation doses for operators at the body, shoulder, or thyroid level, with advantage at the wrist when using the left radial approach. 19ah et al 20  Be aware of factors that increase x-ray exposure, such as patient's BMI.

HIGHLIGHTS
Cardiac procedures carry radiation risk.
Practical tips across all subspecialties.
Improve radiation safety with education/ advocacy.Maximize distance from the image intensifier.absorbing drapes outside the beam path or use of a radiation protective cabin to reduce exposure to the operator's head during long CIED cases may also be useful but are not routinely utilized. 29,30Although not always practical, limiting the maximum number of implants per year per physician may also be considered.

PRACTICAL TIPS.
Maximize the use of EAM and ICE.Until recently, physician radiation exposure during RHC and EMB was poorly understood.In a recent study, 31 investigators observed that head-level

Stochastic effects
Refers to certain adverse effects of radiation exposure, such as cancer.Stochastic effects occur by chance, with increasing probability at increased doses of exposure, however the severity of the outcome is independent of the dose.

Deterministic effects
Refers to other adverse effects of radiation exposure, such as cataracts and reproductive system effects.Unlike stochastic effects, deterministic effects only occur after a threshold dose is passed, and the severity of the effect increases with dose.
Fluoroscopy X-ray imaging utilized during procedures for guiding equipment within the body.Fluoroscopy utilizes lower doses and lower frame rates to minimize radiation exposure to that which is required for safe manipulation of equipment.

Cine acquisition
Higher quality x-ray images, requiring higher doses and more rapid frame rates.Usually taken in short bursts to allow high quality images to be reviewed after acquisition, eg, coronary angiography.

Fluoroscopic time (min)
The duration during a procedure that fluoroscopy is active for.This does not include cine acquisition and tends to underestimate the total radiation dose when used in isolation.
Cumulative Air Kerma (Gy) A measure of x-ray energy delivered to the air.Associated with deterministic skin effects.
Dose-area product (Gy/cm 2 ) Product of the radiation dose and beam area.This is an indicator of patient x-ray dose and is linked to the patient's risk of stochastic effects.
Tamirisa et al   inconclusive, and the trend has not caught on in many centers. 35,36One approach that may be underutilized is to perform EMB using EAM in the EP lab. 37 Radiation Exposure in Cardiology study demonstrates significantly higher radiation exposure per case to echocardiographers than interventional cardiologists; 42 this can be substantially reduced with proper cath lab modification and dedicated shields. 43,44Health care systems and professional organizations must help imagers by providing guidelines, education, and resources to minimize exposure. 45ACTICAL TIPS.
Additional shields should be utilized.
Avoid 'backless' style lead aprons, as the interventional echocardiographer will frequently be facing away from the image intensifier. 43ximize distance from the image intensifier and leave the field when imaging guidance is not required.
Be aware of the impact of x-ray projection-steep right anterior oblique imaging significantly increases radiation dose to the transesophageal echocardiographer. 43

PEDIATRIC CARDIOLOGY
To ensure safety, pediatric cardiac proceduralists must adhere to the same safety precautions as adult proceduralists.However, exposure to the patient is even more critical than in adult cardiology.
The practitioner should be aware of factors that may place the pediatric and congenital heart disease patient at higher risk of ionizing radiation.Exposure to ionizing radiation during periods of rapid cell growth and turnover places the young patient at higher risk of the detrimental effects of ionizing radiation.This is further exacerbated by the assumed longer life expectancy of the younger patient.Patients with congenital heart disease often have complex pathology, resulting in challenging structural anomalies and arrhythmias, leading to prolonged and repeated procedures.Thus, optimizing techniques to minimize radiation exposure is vital, as is monitoring the lifetime cumulative dose.
Chosen hardware and provider practices should be optimized for pediatric patients.Patient positioning, shielding, age-appropriate dosing, and reducing radiation scatter are standard practices.[48] Current technologies used in adult cardiology to minimize radiation exposure may not be feasible in this population due to the anatomic and size limitations.Therefore, using more traditional imaging such as transesophageal echocardiography should be considered to maintain safety and minimize radiation exposure.

PRACTICAL TIPS.
Consider the cumulative exposure risk to the younger patient.
Adopt low/no fluoroscopy and nonfluoroscopic imaging approaches where feasible.

ORTHOPEDIC INJURY AND STRAIN
Use of heavy lead aprons, which provide radiation protection may result in orthopedic injury.This is particularly relevant when the operator stands for several hours, depending on the case duration and complexity.[51] The 2017 Society of Interventional Radiology document provided practical advice on reducing such injury; 52 however, there are no specific cardiology society guidelines at the present time.These should be considered as a matter of importance.Using appropriately sized, low-weight lead aprons is important to minimizing orthopedic problems.
Integrating lead-free environment into the current procedural laboratories using encapsulated patient Use low-weight lead aprons where available, and call upon organizations to acquire them if they are unavailable.
Remove lead aprons and take breaks between cases.
Maximize procedural use of nonfluoroscopic guidance.
Avoid movements that cause discomfort, and be aware of one's own posture.
Advocate for and use lead-free systems.
Exercises to maintain flexibility and strength may prevent long-term spinal problems.

PREGNANCY
The difficulty of family planning and pregnancy while being exposed to radiation may cause women to veer away from cardiology as a field.Recent estimates suggest that <10% of interventional cardiologists are female, and surveys have suggested that more than 25% of women see radiation exposure as a barrier to selecting interventional cardiology as a subspecialty. 53nerally, the risks of fetal exposure to ionizing radiation are highest at the beginning of pregnancy and decrease as the fetus matures. 54 3.Although these risks are frightening for the pregnant proceduralist to consider, several studies suggest that, with proper radiation safety measures, fetal x-ray exposure is essentially negligible. 53The standard radiation safety measures described earlier in this document all remain applicable during pregnancy; however, there are some additional considerations:  Radiation Exposure in Cardiology Pregnant women may be at higher risk of orthopedic injury due to uterine gravidity combined with the weight of a lead apron.For this reason, lighterweight lead aprons should be preferred, although a minimum of 0.5 mm lead equivalency is still advised. 53Dedicated pregnancy lead aprons should be made available by organizations to maximize safety and comfort.Alternatively, some may opt to wear an additional lead apron for abdominal protection, 53,54 though this may increase the risk of orthopedic strain.Using suspended lead suits has been shown to decrease the radiation exposure and mitigate technical difficulties associated with the traditional ceiling-mounted radiation shields. 55tal dosimeter should be utilized during pregnancy.This allows real-time monitoring to ensure safety and provides reassurance.
Breastfeeding may be a concern for some when performing fluoroscopic procedures.Fortunately, there is no evidence that ionizing radiation creates any additional risk to the breastfed baby, 53  Overall, most evidence suggests that, with appropriate precautions, pregnant cardiologists can safely continue procedures. 53,54ACTICAL TIPS.
Use pregnancy-specific lead aprons.
Wear a fetal dosimeter.Ensure standard radiation safety measures are utilized.
Practical tips across all cardiac specialties are organized in a tabulated format for quick reference (Table 4).

CONCLUSIONS
randomized operators to either right or left radial access and prospectively enrolled transfemoral procedures in a registry.Median measures of radiation exposure were not significantly different between left vs right radial in a population with high risk of transradial failure; however, all measurements of radiation were lowest in the transfemoral group.There remains a wide variation in practice, with the PROTECTION VIII study demonstrating a 5.3-fold variability of median dose area product between cath labs in Germany. 15Novel image enhancement technologies have been adopted to improve coronary stent visualization while minimizing x-ray duration.Tian et al 22 evaluated the CLEARstent and CLEARstent Live (Siemens Healthineers, Germany) stent visualization modalities.They noted that enhanced imaging technology was associated with reduced contrast usage, radiation dose, and procedure time.The same results were observed in a subgroup of patients with chronic kidney disease.While all personnel in the Cath lab should have their radiation exposure monitored with a dosimeter, standard dosimeters are limited by the lack of realtime updates on cumulative exposure.Operators may not be notified about their radiation dose for months until their dosimeter is reviewed.Dosimeters, which facilitate real-time radiation monitoring encourage staff to react accordingly and use strategies to limit exposure.Finally, technical advancements like robotic PCI may lower radiation exposure with similar overall fluoroscopy time, despite longer total procedural time. 23Adoption of such technologies has been limited due to technical and financial considerations.PRACTICAL TIPS.

Adopt
fluoroless ablation.Prioritize fluoroless techniques during EP Training.Stereotaxis utilization, where available.Utilize ultrasound-guided access for CIED implant.ADVANCED HEART FAILURE/ TRANSPLANT CARDIOLOGY AHF procedures may involve right heart catheterizations (RHC) and endomyocardial biopsy (EMB).There is growing interest in the AHF community in pursuing diagnostic catheterization, placement of pulmonary artery pressure monitoring devices, trans-septal devices, intra-aortic balloon pumps, and other percutaneous hemodynamic support devices.
Radiation Exposure in Cardiology radiation doses during RHC were lower than those observed with DCoA or PCI; however, radiation doses during EMB were like DCoA.They observed that a physician performing an RHC or EMB would receive more radiation than a physician performing DCoA when normalized to dose area product.This could be explained by 2 factors.Firstly, RHC and EMB operators utilize the internal jugular vein for access, decreasing distance from the radiation source and posing an increased risk of radiation scatter.It is known that intensity of radiation is inversely proportional to the square of the distance, and proximity to radiation source increases the expected radiation dose.32Secondly, operator positioning required for manipulation of the catheter may preclude the use of ceiling-mounted shields, which have been demonstrated to decrease radiation exposure.17,33RHC and EMB performed via femoral access require fluoroscopy for navigation of the inferior vena cava through to the pulmonary artery.There is evidence to suggest that using the

FIGURE 2
FIGURE 2 Intracardiac Echocardiographic Image Showing Ablation Catheter Within the Coronary Sinus

FIGURE 1
FIGURE 1 Illustration of an Electroanatomical Reconstruction of the Heart and Pulmonary Arteries in 2 Views Using Ensite X Cardiac Mapping System This has multiple advantages, including reduced radiation exposure, improved diagnostic detail via voltage mapping, improved diagnostic yield by targeting substrate based on voltage, and potentially ablation of concurrent arrhythmia in the same procedure.Insertion of a pulmonary artery monitoring device is similar to RHC, except that cineangiography of the pulmonary artery is needed to assess anatomy, and additional fluoroscopy is needed to confirm positioning/removal of the guiding catheter after implantation of the device.PRACTICAL TIPS.Minimize fluoroscopy except where cardiac device dislodgement is a potential risk.Wedge positioning during RHC can be confirmed with obtaining a wedge saturation, which confirms position and ensures accuracy of the left-sided pressures.Limit the use of fluoroscopy with EMB by watching the bioptome using right anterior oblique projection and avoiding left anterior oblique projection.Consider the utility of EAM systems in the EP lab for EMB.CARDIAC IMAGING NUCLEAR CARDIOLOGY.Nuclear cardiology procedures utilize radioisotopes for visualization and assessment of myocardial function.Single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI) utilizes 99mTc and 201Tl; radionuclide ventriculography utilizes 99mTc; and positron emission tomography utilizes 18F-FDG, 82Rb, and ammonia 13N. 38Radiation-induced injury can occur from gamma-ray emissions during SPECT MPI and radionuclide ventriculography or from positron emissions during positron emission tomography scans.Health care personnel handling these radioisotopes are at risk of occupational exposure at multiple stages of the testing process, including the initial handling of these agents prior to patient administration and exposure to patients who become sources of radiation emission to their surrounding environment.39The effective dose of radioisotopes administered determines the magnitude of risk from radiation and differs between the varying radioisotopes.For instance, the full-dose rest and stress protocol with 201Tl confers an effective dose of 21 mSv.In contrast, the full-dose stress-only protocol with 99mTc-sestamibi confers an effective dose of 10 mSv.40 Differing half-lives of radioisotopes determine how long the patient will emit radiation.Lastly, high-energy gamma particles released during nuclear testing are not as well shielded by standard protective equipment.39Standard practices such as minimizing time and maximizing distance from the radiation source should be observed to decrease exposure.Additionally, strategies such as minimizing the effective dose administered to patients can reduce radiation emissions and overall exposure.Finally, separating patients from health care personnel and other patients immediately after receiving radioisotopes to allow for the radiotracers to undergo decay is essential for best safety practices.Table 2 summarizes the utility, half-life, and effective dose of several commonly used radioisotopes.INTERVENTIONAL ECHOCARDIOGRAPHY.Advances in imaging technology have allowed for an increase in catheter-based procedures performed percutaneously under echocardiographic guidance.The field of echocardiography, traditionally considered an attractive field for women partially due to its radiation-free nature, has evolved, and interventional echocardiography has become a popular career path.With the requirement for echocardiographers to participate in fluoroscopic procedures, it is imperative for all practitioners to be aware of ionizing radiation exposure.These procedures are often performed in the cath lab or in hybrid operating rooms, which were not designed with the imaging specialist in mind.During these procedures, echocardiographers typically stand near the fluoroscopic image intensifier, where the greatest amount of radiation exposure occurs.Current designs often lack dedicated radiation shields for imagers.A recent J A C C : A D V A N C E S , V O L . 3 , N O . 4 Doses of $100 mGy within the first 2 weeks of conception may result in abortion.Similar doses during the major periods of organogenesis (3-8 weeks) may result in growth retardation or malformation.There is a risk of impairment of intelligence quotient at doses from 120 to 200 mGy up to week 15, and at doses up to 500 mGy up to week 25.In the third trimester, the risks are lower and are considered like early childhood radiation exposure.These aspects are summarized in Table although standard radiation protection measures should continue to be applied.If a pregnant cardiologist does not feel 'safe' in the cath lab despite the above-mentioned ways of mitigating risk to the fetus, an option to stay out of the cath lab during pregnancy must be provided.Program directors and employers should be supportive of this decision and should consider altering the schedule that will allow the pregnant trainee/cardiologist to perform noninvasive duties like research, outpatient patient management, or inpatient consultation services that do not require exposure to radiation.56Other considerations may include availability of time for expressing and storing breast milk during prolonged procedures and the provision and duration of maternity leave; an in-depth discussion of these aspects is outside of the scope of our document.
While advances have been made, ionizing radiation exposure during cardiology procedures remains an area of concern for many, particularly women in cardiology.Maximizing safety requires both strict adherence to international guidelines and improvements in individual and organizational radiation safety culture. 57Following standard radiation safety measures is important (Central Illustration).importance of using lead-free systems and correct posture, mobility, flexibility, and strengthening exercises to maintain spinal health should not be overlooked.FUNDING SUPPORT AND AUTHOR DISCLOSURES Dr Zieroth has received research grant support, served on advisory boards for, or speaker engagements with AstraZeneca, Bayer, BMS, CENTRAL ILLUSTRATION Tips to Minimize Radiation Exposure Tamirisa KP, et al.JACC Adv.2024;3(4):100863.EAM ¼ electroanatomic mapping; ICE ¼ intracardiac echocardiography; LAO ¼ left anterior oblique; RAO ¼ right anterior oblique.J A C C : A D V A N C E S , V O L . 3 , N O . 4 , 2

TABLE 1
Important Nomenclature Used Throughout This Manuscript

TABLE 3
Pregnancy and Radiation

TABLE 4
Summary of Radiation Safety Practical TipsMinimize fluoroscopy except where cardiac device dislodgement is a potential risk Wedge positioning during RHC can be confirmed with obtaining a wedge saturation, which confirms position and ensures accuracy of the left sided pressures Limit use of fluoroscopy with EMB by watching the bioptome using right anterior oblique projection and avoid left anterior oblique projection Consider the utility of EAM systems in the EP lab for EMBCardiac imagingAdditional shields should be utilized Avoid 'backless' style lead aprons, as the interventional echocardiographer will frequently be facing away from the image intensifier Maximize distance from the image intensifier, and leave the field when imaging guidance is not required Be aware of the impact of x-ray projection-steep right anterior oblique imaging significantly increases radiation dose to the transesophageal echocardiographerPediatric cardiologyConsider the cumulative exposure risk to the younger patient Adopt low/no fluoroscopy and nonfluoroscopic imaging approaches where feasible Orthopedic injury and strain Use low-weight lead aprons where available, and call upon organizations to acquire these if unavailable Remove lead aprons and take breaks between cases Maximize procedural use nonfluoroscopic guidance Avoid movements which cause discomfort and be aware of one's own posture Advocate for and use lead-free systems Exercises to maintain flexibility, and strength may prevent long-term spinal problems BMI ¼ body mass index; CIED ¼ cardiac implantable electronic devices; EAM ¼ electroanatomic mapping; EMB ¼ endomyocardial biopsy; ICE ¼ intracardiac echocardiogram; RHC ¼ right heart catheterization.
Boehringer Ingelheim, Cytokinetics, Eli Lilly, GSK, Janssen, Merck, Novartis, Novo-Nordisk, Otsuka, Pfizer, Roche, Servier, and Vifor Pharma; and serves on a clinical trial committee or as a national lead for studies sponsored by AstraZeneca, Bayer, Boehringer Ingelheim, Merck, Novartis and Pfizer.Nonindustray support was received by Canadian Medical and Surgical KT Group, CCS, CHFS, Charite, EOCI, Liv, Medscape, Ology, PHRI, PACE-CME, Radcliffe, Translational Medicine Academy.Dr Dalal is a speaker for Medtronic.Dr Razminia is related to Abbott.All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.Bar O. Understanding and minimising occupational radiation in the catheterisation laboratory with PISAX and the ACIST CViâ contrast delivery system.Intervent Cardiol.2013;8(1):36-40.2. Roguin A, Goldstein J, Bar O, Goldstein JA.Brain and neck tumors among physicians performing interventional procedures.Am J Cardiol.Doody MM, Freedman DM, Alexander BH, et al.Breast cancer incidence in U.S. radiologic technologists.Cancer.2006;106(12):2707-2715. 4. Vano E, Gonzalez L, Fernández JM, Haskal ZJ.