Potential biomarkers of chronic low-dose radiation exposure for nuclear medicine technologists

PurposeNuclear medicine is the fastest growing segment in imaging due to an increase in demand for procedures, development of advanced scanners and new radioactive tracers. Technologists are exposed to radiation throughout the workday. Key protection approaches are time, distance, and shielding; these can be difficult to achieve since patients are usually the main source of radiation and close contact is required. Technologists in general nuclear medicine receive annual effective doses of approximately 0.1 mSv. Doses in positron emission tomography (PET) imaging can be close to 6 mSv. Without appropriate radiation protection measures, finger doses from handling PET radiopharmaceuticals can exceed the annual dose limit of 500 mSv. Estimates of health risks from low dose-rate exposures are extrapolated from risk coefficients calculated from Japanese atomic bomb survivors. Effects of chronic exposure are obtained from nuclear workers and radiotherapy patients. This review aims to consolidate existing research in biomarkers of low dose radiation exposure to determine whether they may form a part in occupational health monitoring.ConclusionsThe link between chronic low-dose exposure in nuclear medicine technologists and health risks using radiation-related biomarkers as a proxy remains relatively unexplored. Further work is needed to identify and characterize biomarkers in technologists

A higher incidence of chromosomal aberrations in operators performing a large volume of endovascular procedures

British Heart Foundation (FS/17/24/32596 to B.M)

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

Funding Information: On behalf of the Public and Community Oversight Group (PCOG) of the Health Protection Research Unit in Chemical and Radiation Threats and Hazards: Ian Wright; John Phipps; Colette Kelly; Robert Goundry; Eve Smyth; Andrew Wood; Paul Dale (also of the Scottish Environment Protection Agency). On behalf of the Society and College of Radiographers Patient Advisory Group: Lynda Johnson; Philip Plant; Michelle Carmichael – Specialist Senior Staff Nurse Guy's and St Thomas’ NHS Foundation trust.Peer reviewe

Quantification of experimental venous thrombus resolution by longitudinal nanogold-enhanced micro-computed tomography

INTRODUCTION: The assessment of thrombus size following treatments directed at preventing thrombosis or enhancing its resolution has generally relied on physical or histological methods. This cross-sectional design imposes the need for increased numbers of animals for experiments. Micro-computed tomography (microCT) has been used to detect the presence of venous thrombus in experimental models but has yet to be used in a quantitative manner. In this study, we investigate the use of contrast-enhanced microCT for the longitudinal assessment of experimental venous thrombus resolution. MATERIALS AND METHODS: Thrombi induced by stenosis of the inferior vena cava in mice were imaged by contrast-enhanced microCT at 1, 7 and 14days post-induction (n=18). Thrombus volumes were determined longitudinally by segmentation and 3D volume reconstruction of microCT scans and by standard end-point histological analysis at day 14. An additional group of thrombi were analysed solely by histology at 1, 7 and 14days post-induction (n=15). RESULTS: IVC resident thrombus was readily detectable by contrast-enhanced microCT. MicroCT-derived measurements of thrombus volume correlated well with time-matched histological analyses (ICC=0.75, P<0.01). Thrombus volumes measured by microCT were significantly greater than those derived from histological analysis (P<0.001). Intra- and inter-observer analyses were highly correlated (ICC=0.99 and 0.91 respectively, P<0.0001). Further histological analysis revealed noticeable levels of contrast agent extravasation into the thrombus that was associated with the presence of neovascular channels, macrophages and intracellular iron deposits. CONCLUSION: Contrast-enhanced microCT represents a reliable and reproducible method for the longitudinal assessment of venous thrombus resolution providing powerful paired data

Leukocytes and the Natural History of Deep Vein Thrombosis Current Concepts and Future Directions

Observational studies have shown that inflammatory cells accumulate within the thrombus and surrounding vein wall during the natural history of venous thrombosis. More recent studies have begun to unravel the mechanisms that regulate this interaction and have confirmed that thrombosis and inflammation are intimately linked. This review outlines our current knowledge of the complex relationship between inflammatory cell activity and venous thrombosis and highlights new areas of research in this field. A better understanding of this relationship could lead to the development of novel therapeutic targets that inhibit thrombus formation or promote its resolution

An evaluation of the effect of an angiotensin-converting enzyme inhibitor on the growth rate of small abdominal aortic aneurysms: a randomised placebo-controlled trial (AARDVARK)

BackgroundAlthough data are inconsistent, angiotensin-converting enzyme inhibitors (ACE-Is) have been associated with a reduced incidence of abdominal aortic aneurysm (AAA) rupture in analysis of administrative databases.Objectives(1) To investigate whether or not the ACE-I perindopril (Coversyl arginine, Servier) reduces small AAA growth rate and (2) to evaluate blood pressure (BP)-independent effects of perindopril on small AAA growth and to compare the repeatability of measurement of internal and external aneurysm diameters.DesignA three-arm, multicentre, single-blind, randomised placebo-controlled trial.SettingFourteen hospitals in England.ParticipantsMen or women aged ≥ 55 years with an AAA of 3.0–5.4 cm in diameter by internal or external measurement according to ultrasonography and who met the trial eligibility criteria.InterventionsPatients were randomised to receive 10 mg of perindopril arginine daily, 5 mg of the calcium channel blocker amlodipine daily or placebo daily.Main outcome measuresThe primary outcome was AAA diameter growth using external measurements in the longitudinal plane, which in-trial studies suggested was the preferred measure. Secondary outcome measures included AAA rupture, AAA repair, modelling of the time taken for the AAA to reach the threshold for intervention (5.5 cm) or referral for surgery, tolerance of study medication (measured by compliance, adverse events and quality of life) and a comparison of the repeatability of measures of internal and external AAA diameter. Patients were followed up every 3–6 months over 2 years.ResultsIn total, 227 patients were recruited and randomised into the three groups, which were generally well matched at baseline. Multilevel modelling was used to determine the maximum likelihood estimates for AAA diameter growth. No significant differences in the estimates of annual growth were apparent [1.68 (standard error 0.02) mm, 1.77 (0.02) mm and 1.81 (0.02) mm in the placebo, perindopril and amlodipine groups, respectively]. Similarly, no significant differences in the slopes of modelled growth over time were apparent between perindopril and placebo (p = 0.78) or between perindopril and amlodipine (p = 0.89). The results were essentially unaffected by adjustment for potential confounders. Compliance, measured by pill counts, was good throughout (&gt; 80% at all visit time points). There were no significant in-trial safety concerns. Six patients withdrew because of adverse events attributed to the study medications (n = 2 perindopril,n = 4 amlodipine). No patients ruptured their AAA and 27 underwent elective surgery during the trial (n = 9 placebo,n = 10 perindopril,n = 8 amlodipine).ConclusionsWe were unable to demonstrate a significant impact of perindopril compared with placebo or amlodipine on small AAA growth over a 2-year period. Furthermore, there were no differences in the times to reach a diameter of 5.5 cm or undergo surgery among the three groups. Perindopril and amlodipine were well tolerated by this population. External AAA measurements were found to be more repeatable than internal measurements. The observed AAA growth measurement variability was greater than that expected pre trial. This, combined with slower than expected mean growth rates, resulted in our having limited power to detect small differences between growth rates and hence this adds uncertainty to the interpretation of the results. Several further analyses are planned including a multivariate analysis of determinants of AAA growth, an evaluation of the possible differential effect of perindopril on fast AAA growth and an investigation into the roles of central BP and BP variability on AAA growth.Trial registrationCurrent Controlled Trials ISRCTN51383267.FundingThis project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full inHealth Technology Assessment; Vol. 20, No. 59. See the NIHR Journals Library website for further project information. The NIHR Biomedical Research Centre based at Imperial College NHS Trust supported the trial. Servier provided perindopril at no charge.</jats:sec

Radiation Induced DNA Damage in Operators Performing Endovascular Aortic Repair

Background: Radiation exposure during fluoroscopically guided interventions such as endovascular aortic repair (EVAR) is a growing concern for operators. This study aimed to measure DNA damage/repair markers in operators perfoming EVAR. Methods: Expression of the DNA damage/repair marker, γ-H2AX and DNA damage response marker, phosphorylated ataxia telangiectasia mutated (pATM), were quantified in circulating lymphocytes in operators during the peri-operative period of endovascular (infrarenal, branched, and fenestrated) and open aortic repair using flow cytometry. These markers were separately measured in the same operators but this time wearing leg lead shielding in addition to upper body protection and compared with those operating with unprotected legs. Susceptibility to radiation damage was determined by irradiating operators' blood in vitro. Results: γ-H2AX and pATM levels increased significantly in operators immediately after branched endovascular aortic repair/fenestrated endovascular aortic repair (P&lt;0.0003 for both). Only pATM levels increased after infrarenal endovascular aortic repair (P&lt;0.04). Expression of both markers fell to baseline in operators after 24 hours (P&lt;0.003 for both). There was no change in γ-H2AX or pATM expression after open repair. Leg protection abrogated γ-H2AX and pATM response after branched endovascular aortic repair/fenestrated endovascular aortic repair. The expression of γ-H2AX varied significantly when operators' blood was exposed to the same radiation dose in vitro (P&lt;0.0001). Conclusions: This is the first study to detect an acute DNA damage response in operators performing fluoroscopically guided aortic procedures and highlights the protective effect of leg shielding. Defining the relationship between this response and cancer risk may better inform safe levels of chronic low-dose radiation exposure

Perioperative Medicine for Older People Undergoing Surgery Scale Up (POPS-SUp):study protocol

Background: Surgery provides definitive management of many age-related diseases, relieving symptoms or extending life. Age-related physiological decline, multimorbidity, and frailty predispose older people to postoperative complications and incomplete functional recovery, with resultant health and social care costs. These age-related conditions can be optimized using Comprehensive Geriatric Assessment (CGA), thus mitigating perioperative risk to improve clinical outcomes with cost-effectiveness. National organizations advocate CGA-based services for older surgical patients. However, there is variation in the provision of CGA-based perioperative medicine for older people undergoing surgery (POPS) services across the UK National Health Service, resulting in inequitable access for older surgical patients at higher risk, unnecessary deaths, complications, and financial cost. The aim of the POPS Scale Up (POPS-SUp) study is to determine whether CGA-based POPS services can be implemented at scale to cost-effectively improve clinical outcomes for older patients undergoing surgery. Methods: A mixed-methods hybrid implementation–effectiveness interrupted time series study will examine the use of a coproduced implementation strategy to embed CGA-based POPS services at scale in the UK. Co-primary implementation–effectiveness outcomes will be used, namely reach and length of hospital stay, respectively. Evaluation will include an embedded process evaluation, quantitative evaluation of clinical effectiveness and cost-effectiveness, and qualitative appraisal of patient and staff experience. The proposed analysis is to embed a process evaluation using real-time framework analysis, enabling iterative refinement and evaluation of the implementation strategy. Accepted interrupted time series analysis will be used to examine and compare outcomes per participating site. A predefined dissemination strategy has been co-designed with patients/carers, clinical community of practice, and organizational bodies. Conclusion: The anticipation is that POPS-SUp will have impact at the individual (patient and clinician), organizational, and policy levels in the perioperative setting, but with additional potential application to other clinical settings. Registration numbers: ISRCTN 45327 (https://www.isrctn.com/); NIHR 157443 (https://www.nihr.ac.uk/)