Radiation doses for endovascular aortic repairs performed on mobile and fixed C-arm fluoroscopes and procedure phase-specific radiation distribution

National Diagnostic Reference Levels for Standard Descending Thoracic Endovascular Aortic Repair and Optimisation Strategies

OBJECTIVE

The International Commission on Radiological Protection has highlighted the large number of medical specialties that use fluoroscopy outside diagnostic imaging departments without radiation protection programmes for patients and staff. Vascular surgery is one of these specialties. Thoracic endovascular aortic repair (TEVAR) is a complicated procedure requiring radiation protection guidance and optimisation. The recent EU Basic Safety Standards Directive requires the use and periodic updating of diagnostic reference levels (DRLs) for interventional procedures. The aim of this study was to determine doses for patients undergoing TEVAR with mobile Xray systems and hybrid rooms (fixed Xray systems) to obtain national DRLs and to suggest optimisation actions.

METHODS

This was a retrospective cross sectional study. The Spanish Chapter of Endovascular Surgery conducted a national survey in 11 autonomous communities representing around 77.6% of the Spanish population (47.33 million inhabitants). A total of 266 TEVAR procedures from 17 Spanish centres were analysed, of which 53.0% were performed in hybrid operating rooms. National DRLs were obtained and defined as the third quartile of the median values from the different participating centres.

RESULTS

The proposed national DRLs are: for kerma area product (KAP), 113.81 Gy·cm2 for mobile Xray systems and 282.59 Gy·cm2 for hybrid rooms; and for cumulative air kerma (CAK) at the patient entry reference point, 228.38 mGy for mobile systems and 910.64 mGy for hybrid rooms.

CONCLUSION

Based on the requirement to know radiation doses for standard endovascular procedures, this study of TEVARs demonstrated that there is an increased factor of 2.48 in DRLs for KAP when the procedure is performed in a hybrid room compared with mobile C-arm systems, and an increased factor of 3.98 in DRLs for CAK when the procedure is performed with hybrid equipment. These results will help to optimise strategies to reduce radiation doses during TEVAR procedures.

Radiation Exposure in Endovascular Surgery According to Complexity: Protocol for a Prospective Observational Study

In the past decades, we have witnessed tremendous developments in endovascular surgery. Nowadays, highly complex procedures are performed by minimally invasive means. A key point is equipment improvement. Modern C-arms provide advanced imaging capabilities, facilitating endovascular navigation with an adequate open surgical environment. Nevertheless, radiation exposure remains an issue of concern. This study aims to analyze radiation used during endovascular procedures according to complexity, comparing a mobile X-ray system with a hybrid room (fixed X-ray system). This is an observational and prospective study based on a cohort of non-randomized patients treated by endovascular procedures in a Vascular Surgery department using two imaging systems. The study is planned for a 3-year duration with a recruitment period of 30 months (beginning 20 July 2021) and a 1-month follow-up period for each patient. This is the first prospective study designed to describe the radiation dose according to the complexity of the procedure. Another strength of this study is that radiologic variables are obtained directly from the C-arm and no additional measurements are required for feasibility benefit. The results from this study will help us determine the level of radiation in different endovascular procedures, in view of their complexity.

Diagnostic reference levels during fluoroscopically guided interventions using mobile C-arms in operating rooms: A national multicentric survey

PURPOSE

To establish diagnostic reference levels (DRLs) and achievable levels (ALs) for the most common fluoroscopically guided interventions (FGIs) performed in operating rooms using mobile C-arm equipment.

METHODS

A national survey was performed in 57 centers in France. Anonymous data from 6817 patients undergoing FGIs were prospectively collected over a period of 7 months. DRLs (third quartile of the distribution) and ALs (median of the distribution) were determined for each type of intervention in terms of kerma area product (KAP) and fluoroscopy time (FT).

RESULTS

DRLs and ALs were proposed for 31 procedure types related to seven surgical specialties: orthopedics (n = 9), urology (n = 3), vascular (n = 6), cardiology (n = 5), neurosurgery (n = 3), gastrointestinal (n = 3), and multi-specialty (n = 2). DRLs in terms of KAP ranged from 0.1 Gy·cm² for hallux valgus to 78 Gy·cm² for abdominal aortic aneurysm endovascular repair. A factor of 155 was obtained between the FTs for a herniated lumbar disk (0.2 min) and an abdominal aortic aneurysm endovascular repair (31 min). The highest variations were obtained within orthopedic procedures in terms of KAP (ratio 122) and within gastrointestinal procedures in terms of FT (ratio 9). Overall, the FGIs associated with the highest radiation exposure (KAP > 10 Gy·cm²) were found in the cardiology, vascular, and gastrointestinal specialties.

CONCLUSIONS

DRLs and ALs are suggested for a wide range of FGIs performed in operating rooms using a mobile C-arm. We aim at providing a practical optimization tool for medical physicists and surgeons.

Editor's Choice - Comprehensive Literature Review of Radiation Levels During Endovascular Aortic Repair in Cathlabs and Operating Theatres

OBJECTIVE

Occupational exposure is a growing concern among the endovascular specialist community. Several types of imaging equipment are available, such as mobile C arms or hybrid rooms, and some have been shown to deliver higher levels of radiation. A literature review was conducted to identify studies reporting dose data during standard (EVAR) and complex abdominal aortic endovascular repair (fenestrated/branched EVAR [F/BEVAR]).

METHODS

A search of the MEDLINE and the Cochrane databases was performed by two independent investigators using the medical subject heading terms "aortic aneurysms", "radiation", and "humans" over a search period of 10 years. Studies with full text available in English and reporting radiation data independently from the imaging equipment type were included. Experimental studies were excluded.

RESULTS

The lowest dose-area product levels during EVAR and F/BEVAR were identified in hybrid rooms, while the highest were with fixed systems. When adherence to the as low as reasonably achievable principles was stipulated by the authors, dose reports tended to be among the lowest. Several studies, especially of F/BEVAR, report concerning levels of radiation for both patients and staff.

CONCLUSION

Modern imaging equipment type, team involvement with radiation management, and the support of recent imaging technologies such as fusion help to reduce the dose delivered during standard and complex EVAR. Investment in modern imaging technology should be considered in every centre providing endovascular management of aortic aneurysms.

Intraoperative contrast-enhanced ultrasound examination for endoleak detection after complex and infrarenal endovascular aortic repair

OBJECTIVE

The aim of this pilot study was to evaluate intraoperative contrast-enhanced ultrasound (iCEUS) examination for endoleak (EL) detection after complex endovascular aortic repairs (EVAR) in comparison with the standard angiographic completion control.

METHODS

Twenty-one patients (16 male; median age, 73 years [range, 54-81 years]) who underwent single-stage EVARs at our center between October 2016 and October 2018 were included prospectively. The procedures comprised fenestrated and/or branched EVAR (n = 14; 66%), infrarenal EVAR (n = 5; 24%), infrarenal EVAR with bilateral iliac side branch implantation (n = 1; 5%), and infrarenal EVAR with occluder implantation into the internal iliac artery (n = 1; 5%). The used endografts included 14 custom made devices (Cook, Australia Pty Ltd, Brisbane, Australia, n = 6; Vascutek Terumo, Glasgow, Scotland, n = 8) and seven standard infrarenal endografts (Medtronic Inc, Santa Rosa, Calif, n = 5; Vascutek Terumo, Glasgow, Scotland, n = 1; Cook, n = 1). All patients underwent an angiographic completion control for EL detection followed by iCEUS examination. The iCEUS examination was performed by the same examiner who was blinded to the angiography result. In addition to the comparison of the angiographic results to iCEUS examination, iCEUS examination was also compared with the computed tomography angiography (CTA) before discharge (median time to CTA, 5 days [range, 1-7 days]).

RESULTS

Angiography detected eight type II EL, defining the EL origin in four cases. In addition to detecting all of those eight EL, iCEUS examination revealed eight more type II EL not seen on angiography (P = .002) and allowed a definition of the EL origin in all cases. CTA before discharge showed a persistence of only 5 of the 16 type II EL detected by iCEUS examination (31%, P = .002).

CONCLUSIONS

An iCEUS examination can be used as another adjunct to decrease exposure to contrast agent and radiation during EVAR, including complex procedures. A replacement of the completion angiography by iCEUS examination is conceivable for infrarenal EVAR, but also for endovascular type IV or type V repairs. Future studies with larger patient numbers will help to further validate iCEUS examination during complex EVAR.