Editor's Choice – European Society for Vascular Surgery (ESVS) 2023 Clinical Practice Guidelines on Radiation Safety

2 Dimensional 3 Dimensional Image Fusion Artificial Intelligence Artificial Intelligence Fluoroscopy As Low As Reasonably Achievable Air Kerma Automatic Brightness Control Automatic Exposure Control Anterior Posterior Active Personal Dosimeter Cumulative Air Kerma Cone Beam Computed Tomography Computed Tomography Computed Tomography Angiography Dose Area Product Digital Imaging and Communications in Medicine Deoxyribonucleic Acid Detective Quantum Efficiency Diagnostic Reference Level Digital Subtraction Angiography Effective Dose European Basic Safety Standards Directive European Journal of Vascular and Endovascular Surgery Electromagnetic Endovascular Navigation System European Society of Cardiology Entrance Skin Dose European Society for Vascular Surgery European Union European Vascular Surgeons in Training Electron Volt Endovascular Aortic Repair US Food and Drug Administration Fenestrated Endovascular Aortic Repair Field Of View Flat Panel Detector Fiber Optic RealShape Fluoroscopy Time Guideline Committee Guideline Writing Committee Gray “Personal dose equivalent” in soft tissue below body surface International Atomic Energy Agency International Commission on Radiological Protection Instructions For Use Image Intensifier In room Protective Equipment Ionising Radiation Regulations Air Kerma Area Product Kilo Voltage Peak Kilo Voltage Left Anterior Oblique Lifetime Attributable Risk Lower Extremity Peripheral Arterial Disease Lead Free Apron Linear No Threshold Milliamperage Medical Physics Expert Multiplanar Reconstructions National Council on Radiation Protection and Measurements Operator Controlled Imaging Optical Stimulated Luminescence Optically Stimulated Luminescence Dosimeters Lead Personal Protective Equipment PROficiency based StePwise Endovascular Curricular Training programme Peak Skin Dose Quality Assurance Reference Air Kerma Randomised Controlled Trial Radiation Induced Cataract RiboNucleic Acid Region Of Interest Sievert Thoraco-Abdominal Aortic Aneurysm Thoracic Endovascular Aortic Repair Thermoluminescent Dosimeter United Kingdom United Nations Scientific Committee on the Effects of Atomic Radiation Virtual Reality Absorbed dose: The mean energy imparted to matter of mass by ionising radiation. The SI unit for absorbed dose is joule per kilogram and is usually denoted in Gray (Gy). Organ absorbed doses are often quoted. Air kerma (AK): The quotient of the sum of the kinetic energies of all charged particles liberated by uncharged particles in a mass, dm, of air. The AK is measured or calculated at a reference point 15 cm from the isocentre in the direction of the focal spot cumulated from a whole Xray guided procedure. Air kerma area product (KAP, or dose area product, DAP): The KAP is the integral of the air kerma free in air (i.e., in the absence of backscatter) over the area of the Xray beam in a plane perpendicular to the beam axis (usually measured in Gy.cm2). The ICRP now recommends referring to those values as air-air-kerma area product (PKA). C-arm: A fixed or mobile Xray system used for diagnostic imaging and for fluoroscopic guidance during minimally invasive procedures. The name C-arm is derived from the C shaped arm that connects and maintains fixed in space, the Xray source and Xray detector. Collimation: The process of shaping the Xray beam to minimise the radiation field size to the required area of interest using metallic apertures within the Xray source. Computed tomography angiography (CTA): The combination of computed tomography cross sectional imaging with intravenous contrast in order to visualise arterial anatomy and pathology. Cone beam computed tomography (CBCT): A modality, available in modern endovascular operating rooms, that allows rotational acquisition and provides cross sectional imaging of the patient while still on the operating table. Deterministic effects: Deterministic effects of radiation exposure are related to a threshold dose of radiation exposure above which the severity of injury increases with increasing dose. Deterministic effects include harmful tissue reactions and organ dysfunction that result from radiation induced cell death, for example, skin lesions and lens opacities. Diagnostic reference levels (DRLs): Used for medical imaging with ionising radiation to indicate whether, in routine conditions, the patient radiation dose for a specified procedure is unusually high or low for that procedure. DRL values are usually defined as the third quartile of the distribution of the median values of the appropriate DRL quantity observed at each healthcare facility. Digital subtraction angiography (DSA): The acquisition of multiple images in succession within one field of view, with the subsequent digital subtraction of images taken prior to contrast injection, leaving a contrast enhanced image of the vessels, and removing non-vascular structures such as bone. Effective dose: The tissue weighted sum of the equivalent doses in all specified tissues and organs of the body, calculated in Sieverts (Sv). Endovascular operator: Any person carrying out an Xray guided procedure on the vasculature. Endovascular operating room: Any environment where endovascular procedures are carried out with Xray guidance using a C-arm as part of a mobile or fixed imaging system. Endovascular procedure: Any procedure on the vasculature that uses Xray guidance. Entrance skin dose (ESD): The dose absorbed by the skin at the entrance point of the Xray beam measured in Gy. This includes the back scattered radiation from the patient. Equivalent dose: Equivalent dose is the mean absorbed dose in a tissue or organ multiplied by the radiation weighting factor. This weighting factor is 1 for Xrays. Equivalent dose is measured in Sieverts (Sv). European Basic Safety Standards (EBSS) Directive: Describes the standards for protection against the risks associated with exposure to ionising radiation, including radioactive material and natural radiation sources, and also preparedness for the management of emergency exposure situations in the European Union. This is a European Council directive. Filtration: The materials of the Xray tube window and any permanent or variable or adjustable filters that predominantly attenuate the low energetic Xrays in the beam. Fluoroscopy time: The cumulative time spent using fluoroscopy during an endovascular procedure. Gray (Gy): The unit of absorbed radiation dose used to evaluate the amount of energy transferred to matter. One Gy is equivalent to 1 joule/kg. Image intensifier: This component of an imaging system relies on the fact that when Xrays are absorbed in a phosphor screen they convert into light photons. These photons impinge upon a photocathode that emits electrons in proportion to the number of incident Xrays. These photo-electrons are then accelerated across a vacuum in an image intensifier to produce an amplified light image. International Commission on Radiation Protection (ICRP): An independent, international organisation that advances for the public benefit the science of radiological protection, in particular by providing recommendations and guidance on all aspects of protection against ionising radiation. Medical physics expert (MPE): An individual or, if provided for in national legislation, a group of individuals, having the knowledge, training, and experience to act or give advice on matters relating to radiation physics applied to medical exposure, whose competence in this respect is recognised by the competent authority. Peak skin dose (PSD): The dose delivered, by both the primary beam and scatter radiation, at the most irradiated area of the skin. Pulse rate: The number of radiation pulses per second. Radiation exposed worker: Those over the age of 18 years who may be at risk of receiving radiation doses greater than the stipulated public exposure limit of 1 mSv per year of effective dose. Sievert (Sv): The unit used to measure both “effective dose” and “equivalent dose”. For Xrays, 1 Sievert equals 1 Gray (Gy). Stochastic effects: Stochastic effects of radiation exposure are those that occur by chance and, as such, the probability of them occurring, but not the severity, increases with increasing dose. A Linear No Threshold model has been adopted internationally, acknowledging that there is no threshold dose. The development of malignancy is the most common stochastic effect of radiation exposure. The past two decades have witnessed an exponential rise in the number of Xray guided minimally invasive procedures in vascular surgery.1Schanzer A. Steppacher R. Eslami M. Arous E. Messina L. Belkin M. Vascular surgery training trends from 2001–2007: a substantial increase in total procedure volume is driven by escalating endovascular procedure volume and stable open procedure volume.J Vasc Surg. 2009; 49: 1339-1344Abstract Full Text Full Text PDF PubMed Scopus (87) Google Scholar, 2Beck A.W. Sedrakyan A. Mao J. Venermo M. Faizer R. Debus S. et al.Variations in abdominal aortic aneurysm care: a report from the International Consortium of Vascular Registries.Circulation. 2016; 134: 1948-1958Crossref PubMed Scopus (169) Google Scholar, 3Suckow B.D. Goodney P.P. Columbo J.A. Kang R. Stone D.H. Sedrakyan A. et al.National trends in open surgical, endovascular, and branched-fenestrated endovascular aortic aneurysm repair in Medicare patients.J Vasc Surg. 2018; 67 (1690–7)Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar, 4Behrendt C.A. Sigvant B. Kuchenbecker J. Grima M.J. Schermerhorn M. Thomson I.A. et al.Editor's Choice - International variations and sex disparities in the treatment of peripheral arterial occlusive disease: a report from VASCUNET and the International Consortium of Vascular Registries.Eur J Vasc Endovasc Surg. 2020; 60: 873-880Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar With time, many of these endovascular procedures have been validated and have established themselves as the preferred treatment modality based on lower morbidity, mortality, and reduced length of hospital stay, compared with the open surgical alternatives. A large proportion of all vascular interventions are now performed using Xray guided endovascular techniques. Advances in technical expertise, evolving materials technology, and improved imaging capabilities have led to increasingly complex endovascular solutions which are associated with prolonged fluoroscopy times and consequently a rise in radiation exposure to both the patient and the endovascular operating team. There is growing concern regarding the increasing radiation exposure to the patient, and to the whole endovascular team.5Kirkwood M.L. Guild J.B. Arbique G.M. Anderson J.A. Valentine R.J. Timaran C. Surgeon radiation dose during complex endovascular procedures.J Vasc Surg. 2015; 62: 457-463Abstract Full Text Full Text PDF PubMed Google Scholar,6El-Sayed T. Patel A.S. Cho J.S. Kelly J.A. Ludwinski F.E. Saha P. et al.Radiation-induced DNA damage in operators performing endovascular aortic repair.Circulation. 2017; 136: 2406-2416Crossref PubMed Scopus (80) Google Scholar Endovascular operators are key personnel for promoting radiation safety and should work with other key stakeholders in a team approach to protect the patient and all healthcare staff in the endovascular operating room. The risks of radiation exposure are not universally recognised by all, however, because of a poor understanding of key concepts and paucity of educational material directly relevant to vascular surgery.7Mohapatra A. Greenberg R.K. Mastracci T.M. Eagleton M.J. Thornsberry B. Radiation exposure to operating room personnel and patients during endovascular procedures.J Vasc Surg. 2013; 58: 702-709Abstract Full Text Full Text PDF PubMed Scopus (85) Google Scholar The present guidelines on the subject of radiation safety are the first to be written under the auspices of a vascular surgical society. Their explicit aim is to inform the reader about radiation physics and radiation dosimetry, raising awareness of the risks of ionising radiation and describing the methods available to protect against radiation exposure. Key issues of relevance to radiation protection for endovascular operators and all allied personnel have been outlined, and recommendations provided for best practice. This will no doubt also result in better radiation protection for the patient but a focus on patient radiation protection has been reserved, including during diagnostic procedures that require radiation exposure, for future iterations of the guideline. The guideline was written and approved by 14 members who, as well as vascular surgeons and interventional radiologists, included a radiation protection scientist and a medical physicist. The collated work is based on the best available evidence but also relies on the expert opinion of the aforementioned individuals who, as part of the process of gathering the evidence, identified several areas where future studies would better guide opinion. The reader should note that this document offers guidance and does not aim to dictate standards of care. The grading of each recommendation in these guidelines was agreed by a virtual meeting on 18 February 2022. If there was no unanimous agreement, discussions were held to decide how to reach a consensus. If this failed, then the wording, grade, and level of evidence was secured via a majority vote of the Guidelines Writing Committee (GWC) members. The final version of the guideline was submitted in July 2022. These guidelines will be updated according to future evidence and to the decisions made by the European Society for Vascular Surgery (ESVS) Guidelines Committee (GC). The GWC performed a literature search in Medline (through PubMed), Embase, Clinical Trial databases, and the Cochrane Library up to July 2022. Reference checking and hand search by the GWC added other relevant literature. The GWC selected literature based on the following criteria: (1) Language: English; (2) Level of evidence (Table 1). (3) Sample size: Larger studies were given more weight than smaller studies. (4) Relevant articles published after the search date or in another language were included, but only if they were of paramount importance to this guideline.Table 1Levels of evidence according to European Society of CardiologyLevel of evidence AData derived from multiple randomised clinical trials or meta-analysesLevel of evidence BData derived from a single randomised clinical trial or large non-randomised studiesLevel of evidence CConsensus of opinion of the experts and or small studies, retrospective studies, registries Open table in a new tab The recommendations in the guidelines in this document are based on the European Society of Cardiology (ESC) grading system. For each recommendation, the letter A, B, or C marks the level of current evidence (Table 1). Weighing the level of evidence and expert opinion, every recommendation is subsequently marked as Class I, IIa, IIb, or III (Table 2).Table 2Classes of recommendations according to European Society of CardiologyClasses of recommendationsDefinitionClass IEvidence and or general agreement that a given treatment or procedure is beneficial, useful, effectiveClass IIConflicting evidence and or a divergence of opinion about the usefulness or efficacy of the given treatment or procedure Class IIaWeight of evidence or opinion is in favour of usefulness or efficacy Class IIbUsefulness or efficacy is less well established by evidence or opinionClass IIIEvidence or general agreement that the given treatment or procedure is not useful or effective, and in some cases may be harmful Open table in a new tab It is important to note that for the general aspects of radiation safety, international bodies such as the International Commission on Radiological Protection (ICRP), the American Association of Physicists in Medicine, the European Federation of Organisations for Medicine and the International Atomic Energy Agency (IAEA) regularly carry out a thorough synthesis of available evidence to publish guidance documents and inform legislation pertaining to safety standards. Legislation in this context refers to statutory regulations that form the main legal requirements for the use and control of ionising radiation. These overview documents, rather than individual literature citations, have been used in the present guidelines to inform recommendations where this was thought to be appropriate. The present radiation protection guidelines are unique in that several of the recommendations made are actually based on legislation that derives from physics principles and extensive, irrefutable evidence that is the basis of this legislation. There have been extensive discussions within the GWC and Guidelines Committee as we have not been confronted previously with this issue in other guidelines. The conclusion agreed between all parties involved is that we could not make recommendations for what are legal requirements but that it is important for the guidelines to highlight areas where law “must” be followed. For this reason, we have, by unanimous decision, used the wording that recommendations based on legislation “must” be followed and the level of evidence has been marked as “law”. It must be noted that in some instances these are not “global or universal laws” and that the level of evidence denoted as “law” means law under most jurisdictions. The recommendations that are based on law are automatically Class I or III. This guideline also has several recommendations, where the evidence is based on physics principles and the results of studies are absolute truths even in small series. For example, increasing distance from the source of radiation reduces the amount of exposure. This is a principle of physics. The level of evidence used to make this type of recommendation reflects this concept and each of these recommendations is marked with a footnote as a “physics principle.” The GWC was selected by the ESVS to represent both physicians and scientists with expertise in the management of radiation exposure. The members of the GWC have provided disclosure statements of all relationships that might be perceived as real or potential sources of conflict of interest. The ESVS Guidelines Committee (GC) was responsible for the review and ultimate endorsement of these guidelines. All experts involved in the GWC have approved the final document. The guideline document underwent the formal external expert review process and was reviewed and approved by the ESVS GC. This document has been reviewed in three rounds by 25 reviewers, including vascular surgeons, interventional radiologists, and medical physics experts (MPE). All reviewers approved the final version of this document. Patient and public perceptions of radiation safety pertaining to endovascular surgery were captured. This section was written in partnership with patients and members of the public, to ensure the patient perspective is adequately represented in these guidelines and that medical professionals are aware of these views. The individuals consulted included (1) volunteers from the joint Health Protection Research Unit Public and Community Oversight Committee (https://crth.hpru.nihr.ac.uk/wider-engagement/), from the Scottish Environment Protection Agency, and from the Society and College of Radiographers; and (2) patients who had undergone endovascular procedures at Guy’s and St Thomas’ NHS Foundation Trust. The group was consulted about the guidelines and asked what they understood by the risks of radiation exposure. The patients’ opinions on the information that they would have liked pertaining to radiation exposure prior to their endovascular procedures were sought. We explored whether they would have found this useful despite the many unknowns about the risks associated with low dose radiation exposures. The following was understood by the group. Firstly, endovascular surgery, involving the blood vessels, referred to as minimally invasive procedures (those which use only small incisions, resulting in the need for only a small number of stiches) is used to diagnose and treat problems affecting the blood vessels (vascular disease). Secondly, endovascular surgery requires use of ionising radiation, which is radiation of high enough energy to cause damage to cells, potentially resulting in health effects such as cancer. Diagnosis prior to surgery and surveillance commonly requires computed tomography angiography (CTA) using Xrays. It was explained that the use of ionising radiation is in most countries very tightly controlled through legislation; however, the regulations do not cover all the detailed technical aspects of the use of radiation. As such, it is important that appropriate guidance is provided to ensure that use of radiation for each specific discipline is justified and safe. We explained that these ESVS guidelines have been prepared by physicians and scientists who are members of the GWC, selected by ESVS on the basis of their expertise in relevant areas of vascular surgery and radiation protection. The aims of the Guidelines are to outline for medical professionals the key issues of relevance to protect against exposure to ionising radiation. The Guidelines are written for doctors who perform vascular procedures and all allied personnel to provide recommendations for best practice. The Guidelines cover a range of topics including how to measure radiation exposure, the evidence for radiation effects, the current legislation and how to control exposure of the medical personnel through appropriate use of the equipment in the operating room and personal protection, education, and training, and the requirements for the future. The Guidelines and recommendations are based on the state of the art in terms of scientific evidence (based on the available studies), as reviewed by the committee, and regular updates are anticipated. The group stated that medical practitioners must have a good understanding of patient perceptions and expectations. In recent years information has become easy to find; however, the benefits and risks of health effects associated with ionising radiation are not well understood by the non-specialist, and there is a lot of misinformation. The majority perceived the main risk of radiation exposure to be development of cancer. Further, the real and perceived risk varies greatly depending on the source of radiation and how it is used, as well as on the basis of individual experience. It is generally accepted by the public that imaging involving radiation is an important tool; however, practitioners must ensure that the basic concepts such as what radiation is and why it is being used, as well as the value and risks of the specific procedure are clearly explained to every patient. This can be done both face to face, as part of the consent process, and by providing written literature. Anecdotally, some patients reported that this has not happened. Some patients also do not feel it is appropriate to question their doctor and they may say that they understand information provided when this may not be the case. The group, therefore, stated that generic literature about the procedures should include specific mention of the radiation risks and that the medical practitioner should spend time explaining possible risks to the patient to ensure mutual understanding is reached as far as is practical. This should include a clear explanation to the patient who should be aware that it is acceptable to ask questions. It should also be noted that paediatric exposures are not considered here as endovascular procedures on children are very rare; however, this is something that should perhaps be further considered in future iterations of these Guidelines.Tabled 1Recommendation 1Information regarding the risks of radiation exposure must be provided in plain, easy to understand language to patients before undertaking endovascular procedures.ClassLevelReferencesILawEBSS (2013)8Council Directive 2013/59/EURATOM of 5 December 2013 laying down basic safety standards for protection against the dangers arising from exposure to ionising radiation, and repealing Directives 89/618/Euratom, 90/641/Euratom, 96/29/Euratom, 97/43/Euratom and 2003/122/Euratom. Official Journal of the European Union https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2014:013:0001:0073:EN:PDF.Google Scholar Open table in a new tab The group stated that it was important for physicians to be aware that the use of ionising radiation in general is based on three principles. Firstly, the principle of justification, which requires that use of radiation should do more good than harm. Secondly, the principle of optimisation requires that radiation doses should be kept as low as reasonably achievable. Thirdly, the principle of dose limitation requires that the dose to individuals from planned exposure situations, other than medical exposure of patients, should not exceed the appropriate limits. In contrast to non-medical uses of ionising radiation, which are solely process based, medical uses of radiation also depend on the requirements of the individual patient. When ionising radiation is used for medical purposes, exposure of the patient is carried out on the basis of the principles of justification and optimisation. Dose limitation is not considered relevant because a dose of ionising radiation that is too low is undesirable as the images produced may not be of high enough quality to perform a procedure. Justification of radiation exposure for each procedure ensures that the benefit the patient receives from exposure outweighs the radiation detriment and that associated risks are minimised. Justification is the legal responsibility of the registered healthcare professional (who may or may not be the vascular surgeon). The medical practitioner then takes responsibility to ensure that the patient understands the potential risks and that they understand and agree that the risks are worth taking, after weighing against the benefit of the procedure. If the procedure is justified, optimisation ensures that the procedure is carried out in the best possible way to deliver the best medical goal with the least radiation detriment. In medical settings such as during vascular surgery, where the operator of the imaging equipment is not a radiographer or radiologist, the primary responsibility for ensuring the radiation safety of the patient lies with the medical practitioner. In endovascular surgery, ionising radiation is used only for real time imaging purposes, to allow the surgeon to “see” what they are doing inside the body. As such, in practice, the vascular surgeons themselves have direct responsibility for how much radiation the patient receives as it is the vascular surgeon who directly controls when and how often imaging occurs (through use of a pedal or similar). The doses received by patients undergoing endovascular surgery vary depending on a number of factors including the type and complexity of the procedure. There are only a small number of studies which look explicitly at the doses patients receive, and more work is clearly needed here. In general, as discussed in Chapter 2 and Appendix 2, information about the risks associated with ionising radiation exposure come from information gathered through many years of use of ionising radiation in medical and nuclear settings, as well as from experience following atomic bomb testing and radiation accidents. For the doses experienced by patients, direct “tissue reactions” such as skin burns are rare. However, such effects do occur, and the risks and severity vary on a patient by patient basis. Further research is ongoing to better understand and guard against such effects. The patients and members of the public who have contributed to this chapter suggest that future research focuses more clearly on the patient specific dose levels involved in different procedures and how these vary on a case by case basis, which will facilitate clearer discussions on risk between patients and medical professionals prior to procedures being carried out; how cumulative doses might be recorded and used within the medical profession as a whole (something which is not generally done yet); and on the doses received by the practitioners themselves to underpin appropriate protection. Radiation exposure of the patient who receives specific limited exposure as part of treatment or diagnosis does slightly increase the average risk of late effects such as radiation induced cancer, which depends on cumulative lifetime dose, perhaps up to about 5% for a vascular surgery patient, depending on the type of procedure. However, the combined data from all studies suggest that the risk of developing cancer associated with ionising radiation is very small compared with the overall lifetime risk of all cancers, which is now about 50%. Such a risk is acceptable because it is substantially outweighed by the high risk of early death associated with not having the vascular procedure. Hence the procedure is justified. Patients thought they had very little information about radiation exposure and risks prior to their intervention and universally said they would want more despite some of the exact risks being unknown. Several felt that being empowered with information, either in the form of written information or a dedicated website, would raise their curiosity and make them want to find out more. They thought it essential that they be counselled about the risks of radiation exposure prior to their procedure but that it was unlikely the risks would impact their decision to undergo the procedure. It was