Comparison of indirect radiation dose estimates with directly measured radiation dose for patients and operators during complex endovascular procedures

Safety, Effectiveness and Pitfalls of Carbon Dioxide Routine Use as a Contrast Agent for Endovascular Abdominal Aortic Repair

BACKGROUND

Despite the evidence of good performance, carbon dioxide (CO2) routine employment as a contrast agent for endovascular procedures is far from being adopted with its use currently limited to patients with renal impairment and known allergy to iodinated contrast medium (ICM). The purpose of our study is to evaluate the safety and effectiveness of CO2 guided endovascular abdominal aortic aneurysm repair (EVAR) in a standard population and to assess the rationale for a future widespread use.

METHODS

We retrospectively collected data of every patient who underwent CO2 guided standard EVAR from September 2020 to May 2021 and compared them with the data of every patient who underwent EVAR using ICM from December 2019 to August 2020 in our unit. The selection of the contrast medium was not based on any preoperative factor as the contrast medium was routinely used in every patient in both periods. The primary end point of the study was the technical success rate. Secondary end points were the early and late complication rates, radiation exposure and renal function impairment.

RESULTS

49 patients underwent ICM guided EVAR and 52 patients underwent CO2 guided EVAR in our unit in the time frames specified above. The technical success rate was 100% in both groups with no accidental coverage of any target vessel. Intraoperative endoleaks were observed in 14% of ICM patients and 25% of CO2 patients. The radiation exposure was higher in the CO2 group if compared to the ICM group (311.48 vs. 159.86 median mGy/cm2 - P < 0.001). The incidence of postoperative acute kidney injury was low and similar in the 2 groups. No significant worsening over time of the renal function has been reported in both groups.

CONCLUSIONS

EVAR can be safely performed under CO2 guidance without the integration of any quantity of ICM but with an increase in radiation exposure. The nephroprotective role of CO2 guided EVAR in a standard population is unclear and the same role in renal impaired patients should be validated with further studies on selected populations.

Intravascular Ultrasound in the Detection of Bridging Stent Graft Instability During Fenestrated and Branched Endovascular Aneurysm Repair Procedures: A Multicentre Study on 274 Target Vessels

OBJECTIVE

The use of intravascular ultrasound (IVUS) reduces contrast medium use and radiation exposure during conventional endovascular aneurysm repair (EVAR). The aim of this study was to evaluate the safety and efficacy of IVUS in detecting bridging stent graft (bSG) instability during fenestrated and branched EVAR (F/B-EVAR).

METHODS

This was a prospective observational multicentre study. The following outcomes were evaluated: (1) technical success of the IVUS in each bSG, (2) IVUS findings compared with intra-operative angiography, (3) incidence of post-operative computed tomography angiography (CTA) findings not detected with IVUS, and (4) absence of IVUS related adverse events. Target visceral vessel (TVV) instability was defined as any branch or fenestration issues requiring an additional manoeuvre or re-intervention. Any IVUS assessment that detected stenosis, kinking, or any geometric TVV issue was considered to be branch instability. All procedures were performed in ad hoc hybrid rooms.

RESULTS

Eighty patients (69% males; median age 72 years; interquartile range 59, 77 years) from four aortic centres treated with F/B-EVAR between January 2019 and September 2021 were included: 70 BEVAR (21 off the shelf; 49 custom made), eight FEVAR (custom made), and two F/B-EVAR (custom made), for a total of 300 potential TVVs. Two TVVs (0.7%) were left unstented and excluded from the analysis. The TVVs could not be accessed with the IVUS catheter in seven cases (2.3%). Furthermore, 17 (5.7%) TVVs could not be examined due to a malfunction of the IVUS catheter. The technical success of the IVUS assessment was 91.9% (274/298), with no IVUS related adverse events. Seven TVVs (2.5%) showed signs of bSG instability by means of IVUS, leading to immediate revisions. The first post-operative CTA at least 30 days after the index procedure was available in 268 of the 274 TVVs originally assessed by IVUS. In seven of the 268 TVVs (2.6%) a re-intervention became necessary due to bSG instability.

CONCLUSION

This study suggests that IVUS is a safe and potentially valuable adjunctive imaging technology for intra-operative detection of TVV instability. Further long term investigations on larger cohorts are required to validate these promising results and to compare IVUS with alternative technologies in terms of efficiency, radiation exposure, procedure time, and costs.

Protected and Unprotected Radiation Exposure to the Eye Lens During Endovascular Procedures in Hybrid Operating Rooms

OBJECTIVE

Radiation cataract has been observed at lower doses than previously thought, therefore the annual limit for equivalent dose to the eye lens has been reduced from 150 to 20 mSv. This study evaluated radiation exposure to the eye lens of operators working in a hybrid operating room before and after implementation of a dose reduction program.

METHODS

From April to October 2019, radiation exposure to the first operator was measured during all consecutive endovascular procedures performed in the hybrid operating room using BeOSL H_p(3) eye lens dosimeters placed both outside and behind the lead glasses (0.75 mm lead equivalent). Measured values were compared with data from a historic control group from the same hospital before implementation of the dose reduction program.

RESULTS

A total of 181 consecutive patients underwent an endovascular procedure in the hybrid operating room. The median unprotected eye lens dose (outside lead glasses) of the main operator was 0.049 mSv for endovascular aortic repair (EVAR) (n = 30), 0.042 mSv for thoracic endovascular aortic repair (TEVAR) (n = 23), 0.175 mSv for complex aortic fenestrated or branched endovascular procedures (F/BEVAR; n = 15), and 0.042 mSv for peripheral interventions (n = 80). Compared with the control period, EVAR had 75% lower, TEVAR 79% lower, and F/BEVAR 55% lower radiation exposure to the unprotected eye lens of the first operator. The lead glasses led to a median reduction in the exposure to the eye lens by a factor of 3.4.

CONCLUSION

The implementation of a dose reduction program led to a relevant reduction in radiation exposure to the head and eye lens of the first operator in endovascular procedures. With optimum radiation protection measures, including a ceiling mounted shield and lead glasses, more than 440 EVARs, 280 TEVARs, or 128 FEVARs could be performed per year before the dose limit for the eye lens of 20 mSv was reached.

Comparison of Shielding Material Dispersion Characteristics and Shielding Efficiency for Manufacturing Medical X-ray Shielding Barriers

During medical diagnoses, X-ray shielding barriers are used to protect against direct and indirect X-rays. Currently, lead is used as the primary material for shielding barriers; however, the demand for eco-friendly shielding barriers has been increasing. Conventionally, shielding barriers are manufactured using a mechanically bonded combination of lead and aluminum; however, in this study, a plastic-based injection-molded product was developed using tungsten as an eco-friendly alternative to lead. A new process technology was required for mixing tungsten-which can be difficult to process-with a polymer. Consequently, the mixing conditions within the injection molding machine and the related compounding technology factors were analyzed. The process technology considered the pre-mixing method using powdery polymer, particle dispersion method, number of screw rotations, and amount of filler input. The product's shielding performance was then analyzed. The tungsten content of the 2-mm thick barrier manufactured using the proposed method was 90 wt%, and the lead equivalent was 0.321 mmPb. To increase the effectiveness of injection molding in the manufacturing process, specific hourly compounding conditions were proposed. Consequently, the process technology method developed in this study can be considered suitable for manufacturing various shielding barriers.

Influence of safety glasses, body height and magnification on the occupational eye lens dose during pelvic vascular interventions: a phantom study

Objective

By simulating a fluoroscopic-guided vascular intervention, two differently designed radiation safety glasses were compared. The impacts of changing viewing directions and body heights on the eye lens dose were evaluated. Additionally, the effect of variable magnification levels on the arising scattered radiation was determined.

Methods

A phantom head, replacing the operator’s head, was positioned at different heights and rotated in steps of 20° in the horizontal plane. Thermoluminescent dosimeters (TLD), placed in the left orbit of the phantom, detected eye lens doses under protected and completely exposed conditions. In a second step, radiation dose values with increasing magnification levels were detected by RaySafe i3 dosimeters.

Results

Changing eye levels and head rotations resulted in a wide range of dose reduction factors (DRF) from 1.1 to 8.5. Increasing the vertical distance between the scattering body and the protective eyewear, DRFs markedly decreased for both glasses. Significant differences between protection glasses were observed. Increasing magnification with consecutively decreasing FOV size variably reduced the dose exposure to the eye lens between 47 and 83%, respectively.

Conclusion

The safety glasses in the study effectively reduced the dose exposure to the eye lens. However, the extent of the protective effect was significant depending on eye levels and head rotations. This may lead to a false sense of safety for the medical staff. In addition, the application of magnification reduced the quantity of scattering dose significantly. To ensure safe working in the Cath-lab, additional use of protective equipment and the differences in design of protective eyewear should be considered.

Key Points

• Eye lens dose changes with physical size of the interventionist and viewing direction.

• The use of magnification during fluoroscopic-guided interventions reduces scattered radiation.

A critical appraisal of the quality of guidelines for radiation protection in interventional radiology using the AGREE II tool: A EuroAIM initiative

PURPOSE

To systematically review and assess the methodological quality of guidelines for radiation protection in interventional radiology.

MATERIALS AND METHODS

On April 15^th, 2021, a systematic search for guidelines on radiation protection in interventional radiology was performed using MEDLINE, EMBASE, National Guideline Clearinghouse, and National Institute for Health and Clinical Excellence databases. Among retrieved guidelines, we then excluded those not primarily focused on radiation protection or on interventional radiology. Authors' professional role and year of publication were recorded for each included guideline. Guideline quality evaluation was performed independently by three authors using the six-domain tool "AGREE II", with an overall guideline quality score divided into three classes: low (<60%), acceptable (60-80%), and good quality (>80%).

RESULTS

Our literature search identified 106 citations: after applying exclusion criteria, 11 guidelines published between 2009 and 2018 were included, most of their authors being interventional radiologists (168/224, 75%). Overall quality of included guidelines was acceptable (median 72%, interquartile range 64-83%), with only one guideline (9%) with overall low quality and four guidelines (36%) with overall good quality. Among AGREE II domains, "Scope and Purpose", "Clarity of Presentations", and "Editorial Independence" had the best results (87%, 76%, and 75% respectively), while "Applicability", "Rigor of Development", and "Stakeholder Involvement" the worst (46%, 49%, and 52% respectively).

CONCLUSION

Considering all guidelines, the overall methodological quality was acceptable with one third of them reaching the highest score class. The "Applicability" domain had the lowest median score, highlighting a practical implementation gap to be addressed by future guidelines.

Intravascular Ultrasound in Branched and Fenestrated Endovascular Aneurysm Repair: Initial Experience in a Single-Center Cohort Study

PURPOSE

To evaluate intravascular ultrasound (IVUS) safety and efficacy to detect visceral stenting issues during complex endovascular aneurysm repair through branched and fenestrated repair (B-FEVAR).

MATERIALS AND METHODS

A single-center retrospective analysis of 33 bridging stents assessed intraoperatively using IVUS between January and September 2020 was performed. Ten aortic aneurysm patients [7 thoracoabdominal / 1 pararenal / 2 juxtarenal; 3 females; mean age 73 years [range 70-77 years]) were included. Eight BEVAR (5 standard; 2 custom-made) and 2 FEVAR (custom-made) were performed. The study assessed the safety and efficacy of IVUS utilization to detect immediate branch instability after visceral stenting in the case of B-FEVAR. The primary safety endpoint was defined as the absence of IVUS-related adverse events. The primary efficacy endpoint was defined as the composite of technical success of the IVUS-assessment in each target visceral vessels (TVVs), the rate of IVUS-findings divided as prompting additional maneuvers or not, and the incidence of postoperative computed tomography angiography findings compared with intraoperative assessment.

RESULTS

There were no IVUS-related adverse events. The technical success of the IVUS-assessment was achieved in all TVVs. No technical issues compromised the evaluation of the intended vessel. Among the 7 findings identified by IVUS, 3 were suspected at the angiography. In all, 57% (4/7) had normal final angiography. IVUS was able to detect a 12% (4/33) intraoperative branch instability not identified/suspected at the completion angiography. The IVUS assessment led to an immediate revision in 5 (15%) vessels. A total of 57% (4/7) of the issues were detected in patients undergoing primary BEVAR. The remaining 43% (3/7) was detected in patients undergoing secondary intervention for branch instability.

CONCLUSION

IVUS was safe as an adjunctive imaging technique to assess completion after B-FEVAR. It demonstrated efficacy in the detection of intraoperative issues missed by angiography. Further investigations are required to validate these promising results.

Automated Image Fusion Guidance during Endovascular Aorto-Iliac Procedures: A Randomized Controlled Pilot Study

BACKGROUND

The benefits of imaging guidance using a new fully automated fusion process (CYDAR) have been demonstrated during endovascular aortic aneurysm repair, but little is known about its use during aorto-iliac occlusive disease endovascular revascularization. The aim of this study was to evaluate the influence of CYDAR image fusion guidance during endovascular treatment of symptomatic aorto-iliac occlusive lesions, compared with control patients treated using standard 2D fluoroscopy alone.

METHODS

This is a single-center randomized controlled pilot study that recruited patients undergoing aorto-iliac endovascular revascularization.

RESULTS

Between January 2019 and February 2020, 37 patients with symptomatic aorto-iliac lesions were enrolled: 18 were assigned to the fusion group and 19 to the control group. Patients and lesions characteristics were well balanced between both study groups. The technical success of the procedure was 100% in the Fusion group and 94% in the control group. All radiation-related parameters were lower in the fusion compared to the control group, including: median DAP 18.5 Gy.cm2 vs. 21.8 Gy.cm2; Air Kerma 0.10 Gy vs. 0.12 Gy; fluoroscopy dose 4.2 Gy.cm² vs. 5.1 Gy.cm²; and number of DSA 7.5 vs. 8. The volume of iodinated contrast used was higher in the fusion group: 41 mL vs. 30 mL. The total procedure time was the same in both groups:60 min vs. 60 min.

CONCLUSIONS

The results of this pilot study suggest the use of fusion imaging in endovascular treatment of aorto-iliac disease results in reduction in radiation-related measured parameters with no change in procedure time and higher doses of iodinated contrast used. These results need to be further investigated in a larger, adequately powered study.

How to Measure/Calculate Radiation Dose in Patients?

Patients in fluoroscopically guided interventions (FGI) may be exposed to substantial radiation dose levels (SRDL). The most commonly reported adverse reactions are skin injuries with erythema or necrosis. It is therefore important for the interventional radiologist to know deterministic effects with their threshold doses. If possible all relevant modality parameters should be displayed on the interventionalists screen. Dosimetric parameters should be displayed in digital imaging and communications in medicine (DICOM) units and stored as DICOM Radiation Dose Structured Report (RDSR). The peak skin dose (PSD) is the most relevant risk parameter for skin injuries. Dose management systems (DMS) help optimising radiation exposure of patients. However, their calculation of skin dose maps is only available after a FGI. Therefore, dose maps and PSD should preferably be calculated and displayed in real time by the modality.

The impact of x-ray incident angle on indirect fluoroscopy skin dose estimation

Indirect dosimetry to calculate peak skin dose (PSD) is generally based on reference air kerma or kerma-area-product, with effects of table attenuation, inverse square law and backscatter factor applied. When the incident x-ray beam angle changes, these factors would change as well. The purpose of this study is to identify the impact of incident x-ray beam angle on the accuracy of indirect PSD calculation and develop a correction method. Monte Carlo simulation was conducted to assist analytical equation derivation and to validate the developed analytical method. Direct PSD measurements were performed a Siemens Artis Zee biplane fluoroscopy and a GE OEC C-Arm at different angles to validate the proposed correction method and its independence of fluoroscopy systems. Compared with MC simulated PSD, the derived analytical equation successfully predicts these PSD changes for incident angles of 0, 15, 30 and 40 degrees, with the residual error magnitude of 0.3%–3.1% corresponding to different SSDs. The agreement between calculated PSD also agrees well with direct measurement.

Hybrid Operating Room System for the Treatment of Thoracic and Abdominal Aortic Aneurysms: Evaluation of the Radiation Dose Received by Patients

In recent years, endovascular treatment of aortic aneurysms has attracted considerable attention as a promising alternative to traditional surgery. Hybrid operating room systems (HORSs) are increasingly being used to perform endovascular procedures. The clinical benefits of endovascular treatments using HORSs are very clear, and these procedures are increasing in number. In procedures such as thoracic endovascular aortic repair (TEVAR) and endovascular aortic repair (EVAR), wires and catheters are used to deliver and deploy the stent graft in the thoracic/abdominal aorta under fluoroscopic control, including DSA. Thus, the radiation dose to the patient is an important issue. We determined radiation dose indicators (the dose–area product (DAP) and air karma (AK) parameters) associated with endovascular treatments (EVAR and TEVAR) using a HORS. As a result, the mean ± standard deviation (SD) DAPs of TEVAR and EVAR were 323.7 ± 161.0 and 371.3 ± 186.0 Gy × cm², respectively. The mean ± SD AKs of TEVAR and EVAR were 0.92 ± 0.44 and 1.11 ± 0.54 Gy, respectively. The mean ± SD fluoroscopy times of TEVAR and EVAR were 13.4 ± 7.1 and 23.2 ± 11.7 min, respectively. Patient radiation dose results in this study of endovascular treatments using HORSs showed no deterministic radiation effects, such as skin injuries. However, radiation exposure during TEVAR and EVAR cannot be ignored. The radiation dose should be evaluated in HORSs during endovascular treatments. Reducing/optimizing the radiation dose to the patient in HORSs is important.

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.

Analysis of Radiation Exposure during Endovascular Aneurysm Repair

Endovascular aneurysm repair (EVAR) is now the preferred procedure for abdominal aortic aneurysm repair. As a result of the need for fluoroscopy during EVAR, radiation exposure is a potential hazard. We studied the quantity of radiation delivered during EVAR to identify risks for excessive exposure. Fluoroscopy time, contrast volume used, and procedural details were recorded prospectively during EVARs. Using data collected from similar EVARs, an equation was derived to calculate approximate dose-area product (DAP) from fluoroscopy time. DAP values were then compared between procedures in which a relevant postdeployment procedure (PDP) was necessary intraoperatively with those without. Clinical data on 17 patients were collected. The mean age of patients was 68 (±9) years. Fluoroscopy times and approximate DAP values were found to be significantly higher in the seven patients with a PDP compared with the 10 patients without an intraoperative PDP (31.2 [±9.6] vs 22.7 [±6.0] minutes, P = 0.033 and 537 [±165] vs 390 [±103] Gy-cm2, P = 0.033, respectively). The average amount of contrast volume used was not significantly different between groups. Radiation emitted during EVARs with PDPs was significantly greater relative to those without PDPs. Device design and operators should thus aim to decrease PDPs and to minimize fluoroscopy time.

Dual fluoroscopy with live-image digital zooming significantly reduces patient and operating staff radiation during fenestrated-branched endovascular aortic aneurysm repair

OBJECTIVE

Fenestrated-branched endovascular aneurysm repair (F/B-EVAR) is a complex procedure that generates high radiation doses. Magnification aids in vessel cannulation but increases radiation. The aim of the study was to compare radiation doses to patients and operating room staff from two fluoroscopy techniques, standard magnification vs dual fluoroscopy with live-image digital zooming during F/B-EVAR.

METHODS

An observational, prospective, single-center study of F/B-EVAR procedures using Philips Allura XperFD20 equipment (Philips Healthcare, Amsterdam, The Netherlands) was performed during a 42-month period. Intravascular ultrasound, three-dimensional fusion, and extreme collimation were used in all procedures. Intraoperative live-image processing was performed with two imaging systems: standard magnification in 123 patients (81%) and dual fluoroscopy with live-image digital zooming in 28 patients (18%). In the latter, the live "processed" zoomed images are displayed on examination displays and live images are displayed on reference displays. The reference air kerma was collected for each case and represents patient dose. Operating staff personal dosimetry was collected using the DoseAware system (Philips Healthcare). Patient and staff radiation doses were compared using nonparametric tests.

RESULTS

Mean age was 71.6 ± 11.4 years. The median body mass index was 27 kg/m² (interquartile range [IQR], 24.4-30.6 kg/m²) and was the same for both groups. Procedures performed with dual fluoroscopy with digital zooming demonstrated significantly lower median patient (1382 mGy [IQR, 999-2045 mGy] vs 2458 mGy [IQR, 1706-3767 mGy]; P < .01) and primary operator radiation doses (101 μSv [IQR, 34-235 μSv] vs 266 μSv [IQR, 104-583 μSv]; P < .01) compared with standard magnification. Similar significantly reduced radiation doses were recorded for first assistant, scrub nurse, and anesthesia staff in procedures performed with dual fluoroscopy. According to device design, procedures performed with four-fenestration/branch devices generated higher operator radiation doses (262 μSv [IQR, 116.5-572 μSv] vs 171 μSv [IQR, 44-325 μSv]; P < .01) compared with procedures with three or fewer fenestration/branches. Among the most complex design (four-vessel), operator radiation dose was significantly lower with digital zooming compared with standard magnification (128.5 μSv [IQR, 70.5-296 μSv] vs 309 μSv [IQR, 150-611 μSv]; P = .01).

CONCLUSIONS

Current radiation doses to patients and operating personnel are within acceptable limits; however, dual fluoroscopy with live-image digital zooming results in dramatically lower radiation doses compared with the standard image processing with dose-dependent magnification. Operator radiation doses were reduced in half during procedures performed with more complex device designs when digital zooming was used.

Percutaneous AXillary Artery (PAXA) Access at the First Segment During Fenestrated and Branched Endovascular Aortic Procedures

OBJECTIVE

The aim of this study was to assess the feasibility and safety of percutaneous axillary access with vessel closure device closure after puncturing the first segment during endovascular treatment of complex aneurysms with fenestrated and branched endografts (F/BEVAR).

METHODS

The PAXA (Percutaneous AXillary Access) study is a physician initiated, single centre, ambispective, non-randomised study (clinicaltrials.gov: NCT03223311). The primary endpoint was the closure success rate defined as the absence of any vascular injury to achieve haemostasis at the puncture site, requiring any treatment other than manual compression or adjunctive endovascular ballooning. The secondary endpoints were minor access complications, cerebrovascular complication rate, short term access vessel patency, and study cohort anatomical evaluation of the axillary artery.

RESULTS

Sixty-four patients required an upper extremity access during F/BEVAR procedure during study period (November 2016 to July 2019) and were screened for the PAXA study: 59 patients (47 males; median age: 75 years, IQR 69-78) met the study inclusion criteria and were enrolled (one patient had bilateral access). Closure success was obtained in 54 cases (90%) with no open conversion required: five patients received a bare or covered stenting to the AXA and in one patient mechanical failure of the delivery system was recorded. No 30 day permanent peripheral nerve injuries and two non-ipsilateral ischaemic strokes (3.4%) were recorded. Seven patients (12%) had access haematomas managed conservatively associated with closure failure (p = .002), oral anticoagulants therapy (p = .005) and procedure length (p = .028). At short term follow up (6 months), no late complications were observed, and all access vessels were patent.

CONCLUSION

PAXA on the first segment using a large sheath (10-16F) is technically feasible, relatively safe with no need for open conversion but it may require access related secondary endovascular procedures. Further prospective studies are needed to modify the device instruction for use and to put the procedure on label.

Long-term radiation exposure in patients undergoing EVAR: Reflecting clinical day-to-day practice to assess realistic radiation burden

Endovascular repair of aortic aneurysms (EVAR) has become an established treatment option currently applied in an increasing numbers of patients with aortic aneurysms. Advantages include reduced surgical trauma, procedural time, intensive care unit and hospital lengths of stay, blood loss as well as morbidity and mortality.The optimal imaging modalities in EVAR follow-up as well as the appropriate intervals between these follow-ups remain subject of controversial discussion. Objective of this study was the evaluation of the realistic radiation exposure and risk estimate postop EVAR treatment.Of the follow-ups required according to the surveillance schedule during the first year post-EVAR, only 68.3% were actually implemented. Of those required from the second year onwards, an average of 70% was actually performed. During the observation period, each patient underwent a mean of 4.3 CTAs. The median ED calculated from all CTAs was 24. 5 mSv. The minimum and maximum cumulative EDs for the entire observation period were 55 mSv and 310 mSv, respectively.

SURVEY OF KEY RADIATION SAFETY PRACTICES IN INTERVENTIONAL RADIOLOGY: AN IRISH AND ENGLISH STUDY

Interventional radiology is a rapidly evolving speciality with potential to deliver high patient radiation doses, as a result high standards of radiation safety practice are imperative. IR radiation safety practice must be considered before during and after procedures through appropriate patient consent, dose monitoring and patient follow-up. This questionnaire-based study surveyed fixed IR departments across Ireland and England to establish clinical practice in relation to radiation safety. Pre-procedure IR patient consent includes all radiation effects in 11% of cases. The patient skin dose surrogate parameter of Kerma to air at a reference point (Kar) is under-reported. Only 39% of respondents use a substantial radiation dose level and inform patients after these have been reached. Poor compliance with unambiguous, readily available best practice guidance was observed throughout highlighting patient communication, patient dose quantification and subsequent patient dose management concerns.

Radiation exposure during non-thrombotic iliac vein stenting

Objective

Fluoroscopic-guided interventions have become a major part of the modern vascular surgeon’s practice. Imaging is typically required to safely and effectively perform both simple and complex endovascular interventions. With an ever-increasing volume of fluoroscopic-guided interventions being performed each year, the minimization of harmful radiation exposure has become of paramount concern for both patients and providers. The purpose of this study was to identify the extent of radiation exposure associated with venography and iliac vein stenting, an intervention utilized in the management of chronic venous insufficiency.

Methods

This was a single-center, retrospective analysis of 40 venograms performed on 29 unique patients over a three-month period. Patients with signs and symptoms of chronic venous insufficiency who failed conservative therapy underwent evaluation of the vena cava and iliofemoral veins with venography and intravascular ultrasound. Stent placement was performed if a >50% cross-sectional area or diameter reduction was identified via intravascular ultrasound. All patients were found to have non-thrombotic iliac vein lesions. All patients wore two individual film badge dosimeters – one on their chest and the other on the abdomen. The same mobile C-arm system was used for all interventions.

Results

There were 15 males and 14 females, with an average age of 70.6 years old (SD ± 9.5; range 53–89) and a mean body mass index of 33.9 kg/m2. Sixteen limbs had C6 disease, 10 had C4 disease, and 14 had C3 disease. Thirty-eight of the 40 procedures resulted in stent placement, with an average of 1.13 stents placed per intervention. The average fluoroscopy time was 76.5 s (SD ± 36.9; range 7.8–209.5), and the mean cumulative air kerma was 1.08 mGy (SD ± 0.55; range 0.362–2.24). Average cumulative air kerma was higher in procedures resulting >1 stent placement compared to those with placement of ≤1 stent (1.44 vs. 1.02 mGy; p = 0.04). Fluoroscopy time was also higher in procedures with >1 stent placed (120.1 vs. 68.8 s; p = 0.0004). The mean deep dose equivalent per procedure from the patient-worn abdominal badge was 0.221 mSv.

Conclusion

With the adjunctive use of intravascular ultrasound, iliac vein stenting can be safely and effectively performed with very low utilization of fluoroscopy, and therefore radiation exposure can be minimized for both patients and surgeons. Placement of >1 iliac vein stent resulted in higher cumulative air kerma and fluoroscopy time.

Patient and operating room staff radiation dose during fenestrated/branched endovascular aneurysm repair using premanufactured devices

INTRODUCTION

Fenestrated endovascular aneurysm repair (FEVAR) is the highest radiation dose procedure performed by vascular surgeons. We sought to characterize the radiation dose to patients and staff during FEVAR procedures with different premanufactured devices.

METHODS

A single-center prospective study of FEVARs was performed over 24 months. Three FEVAR devices were included: off-the-shelf (OTS; t-Branch, p-Branch), Zenith Fenestrated (ZFen), and investigational custom-made devices (CMDs). Radiation doses to the surgeon, trainee, anesthesiologist, and scrub/circulating nurses were measured using a personal dosimetry system (DoseAware, Philips Healthcare, Amsterdam, The Netherlands). Procedure type, patient body mass index (BMI), reference air kerma (RAK), and kerma area product (KAP) were recorded. RAK and KAP were corrected for BMI based on an exponential fit of fluoroscopy dose rate and the dose per radiographic frame. Operator dose was corrected for BMI by the ratio of corrected to actual KAP. A one-sided Wilcox rank-sum test was used to compare personnel radiation doses, RAKs, and KAPs between procedure types. Statistical significance was set at P ≤ .05.

RESULTS

There were 80 FEVARs performed by a single surgeon on a Philips Allura XperFD20 fluoroscopy system equipped with Clarity technology. Average BMI was 27 kg/m². Sixty CMDs (36 four-, 21 three-, and 3 two-vessel fenestrations), 11 ZFens (8 three- and 3 two-vessel fenestrations), and 9 OTS devices (4 p-Branch, 5 t-Branch) were included. ZFens had significantly lower patient (1800 mGy vs 2950 mGy; P = .004), operator (120 μSv vs 370 μSv; P = .004), assistant (60 μSv vs 210 μSv; P = .003), circulator (10 μSv vs 30 μSv; P = .049), and scrub nurse dose (10 μSv vs 40 μSv; P = .02) compared with CMDs. OTS devices had significantly lower operator (220 μSv vs 370 μSv; P = .04), assistant (110 μSv vs 210 μSv; P = .02), and circulator doses (4 μSv vs 30 μSv; P = .001) compared with CMDs. Four-vessel fenestrated devices had significantly higher patient dose (3020 mGy) compared with three-vessel FEVARs (2670 mGy; P = .03) and two-vessel FEVARs (1600 mGy; P = .0007), and significantly higher operator dose (440 μSv) compared with three-vessel FEVARs (170 μSv; P = .0005). Patient dose was lowest with ZFens. Operating room personnel dose was lower with ZFens and OTS devices compared with CMDs. Four-vessel fenestrations required significantly more radiation compared with those involving three-vessel fenestrations; however, the dose increase was only 12% and should not preclude operators from extending coverage, if anatomically required.

CONCLUSIONS

Overall, patient and personnel radiation doses during FEVAR with all devices were within acceptable limits and lower in our series than previously reported.

Radiation Exposure in Endovascular Infra-Renal Aortic Aneurysm Repair and Factors that Influence It

Objective

The endovascular repair of aortic abdominal aneurysms exposes the patients and surgical team to ionizing radiation with risk of direct tissue damage and induction of gene mutation. This study aims to describe our standard of radiation exposure in endovascular aortic aneurysm repair and the factors that influence it.

Methods

Retrospective analysis of a prospective database of patients with abdominal infra-renal aortic aneurysms submitted to endovascular repair. This study evaluated the radiation doses (dose area product (DAP)), fluoroscopy durations and their relationships to the patients, aneurysms, and stent-graft characteristics.

Results

This study included 127 patients with a mean age of 73 years. The mean DAP was 4.8 mGy.m², and the fluoroscopy time was 21.8 minutes. Aortic bilateral iliac aneurysms, higher body mass index, aneurysms with diameters larger than 60 mm, necks with diameters larger than 28 mm, common iliac arteries with diameters larger than 20 mm, and neck angulations superior to 50 degrees were associated with an increased radiation dose. The number of anatomic risk factors present was associated with increased radiation exposure and fluoroscopy time, regardless of the anatomical risk factors.

Conclusion

The radiation exposure during endovascular aortic aneurysm repair is significant (mean DAP 4.8 mGy.m²) with potential hazards to the surgical team and the patients. The anatomical characteristics of the aneurysm, patient characteristics, and the procedure's technical difficulty were all related to increased radiation exposure during endovascular aortic aneurysm repair procedures. Approximately 40% of radiation exposure can be explained by body mass index, neck angulation, aneurysm diameter, neck diameter, and aneurysm type.

Radiation-Induced DNA Damage in Operators Performing Endovascular Aortic Repair

Supplemental Digital Content is available in the text.

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<0.0003 for both). Only pATM levels increased after infrarenal endovascular aortic repair (P<0.04). Expression of both markers fell to baseline in operators after 24 hours (P<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<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.

Investigation of reference levels and radiation dose associated with abdominal EVAR (endovascular aneurysm repair) procedures across several European Centres

OBJECTIVES

Endovascular aneurysm repair (EVAR) is considered the treatment of choice for abdominal aortic aneurysms with suitable anatomy. In order to improve radiation safety, European Directive (2013/59) requires member states to implement diagnostic reference levels (DRLs) in radio-diagnostic and interventional procedures. This study aimed to determine local DRLs for EVAR across five European centres and identify an interim European DRL, which currently remains unestablished.

METHODS

Retrospective data was collected for 180 standard EVARs performed between January 2014 and July 2015 from five specialist centres in Ireland (n=2) and Italy (n=3). Data capture included: air kerma-area product (P_KA), total air kerma at the reference point (K_a,r), fluoroscopic time (FT), number of acquisitions, frame rate of acquisition, type of acquisition, patient height, weight, and gender.

RESULTS

The mean values for each site A, B, C, D, and E were: P_KAs of 4343 ± 994 μGym², 18,200 ± 2141 μGym², 11,423 ± 1390 μGym², 7796 ± 704 μGym², 31,897 ± 5798 μGym²; FTs of 816 ± 92 s, 950 ± 150 s, 708 ± 70 s, 972 ± 61 s, 827 ± 118 s; and number of acquisitions of 6.72 ± 0.56, 10.38 ± 1.54, 4.74 ± 0.19, 5.64 ± 0.36, 7.28 ± 0.65, respectively. The overall pooled 75th percentile P_KA was 15,849 μGym².

CONCLUSION

Local reference levels were identified. The pooled data has been used to establish an interim European DRL for EVAR procedures.

KEY POINTS

• Abdominal endovascular aneurysm repair (EVAR) requires the use of ionising radiation. • EVAR is a minimally invasive procedure for the treatment of abdominal aortic aneurysms. • Diagnostic reference levels (DRLs) are used to monitor patient radiation exposure. • Radiation dose data was collected from five European centres for EVAR procedures. • Local DRLs have been determined and an interim European DRL is proposed.

Physician and Patient Radiation Exposure During Endovascular Procedures

OPINION STATEMENT

Endovascular procedures expose both patients and physicians to fluoroscopic ionizing radiation that carries a dose-dependent risk of acute toxicity and a small, but demonstrable, long-term risk of malignancy due to resultant genetic mutations. Exposure doses vary widely based upon patient-related factors including body size and anatomic complexity, operator technique, procedure type (diagnostic vs. therapeutic), vascular bed imaged, and imaging equipment employed. Effective dosage may vary as much as 200-fold for physicians and 20-fold for patients depending upon the procedure: for example, complex aortic interventions with branched graft devices may convey mean effective doses of more than 0.4 mSv for physicians and 100 mSv for patients, whereas distal, small-vessel angiography may entail mean effective doses of less than 0.002 mSv for physicians and 5 mSv for patients. Particular attention is given to physicians' ocular exposure, which may cause cataract development, and to hand exposure, which is significantly higher than total body exposure when operators work near the x-ray beam. Given the risks of radiation exposure, numerous strategies have been developed to reduce both physician and patient doses. These measures include physician education about dose-reducing imaging techniques, development of low-dose imaging equipment, introduction of new radiation shielding drapes and caps, and real-time dose monitoring. Here, we review physician and patient effective doses of radiation by procedure type as reported in the literature and present recent data regarding dose-reduction strategies.

Meta-analysis of Cumulative Radiation Duration and Dose During EVAR Using Mobile, Fixed, or Fixed/3D Fusion C-Arms

Purpose: To investigate the total fluoroscopy time and radiation exposure dose during endovascular aortic repairs using mobile, fixed, or fixed C-arms with 3-dimensional image fusion (3D-IF). Methods: A systematic search was performed to identify original articles reporting fluoroscopy time (FT) and the kerma area product (KAP) during endovascular aortic repairs. Data were grouped by noncomplex or complex (fenestrated, branched, or chimney) repairs and stratified by type of C-arm. The search identified 27 articles containing 51 study groups (35 noncomplex and 16 complex) that included 3444 patients. Random-effects meta-analysis and meta-regression models were used to calculate the pooled mean estimates of KAP and FT, as well as any effect of equipment or type of intervention. Results are presented with the 95% confidence interval and the statistical heterogeneity ( I2). Results: Within the noncomplex procedure studies, a significant (p<0.001) increase was found in the pooled mean KAP estimate in the fixed C-arm group (181 Gy·cm2, 95% CI 129 to 233; I2=99.7) compared with the mobile C-arm (78 Gy·cm2, 95% CI 59.6 to 97.3; I2=99.6). For complex cases, use of 3D-IF showed a significantly (p<0.001) lower mean KAP (139 Gy·cm2, 95% CI 85 to 191; I2=94%) compared to using fixed C-arms without 3D-IF (487 Gy·cm2, 95% CI 331 to 643; I2=94%). Conclusion: For equivalent fluoroscopy times, the use of a fixed C-arm in noncomplex procedures leads to higher patient radiation doses compared to a mobile C-arm. Complex procedures, which are predominantly performed using fixed C-arms, are associated with the highest radiation dose per intervention. Using fixed C-arms combined with 3D-IF techniques during complex cases might seem an adequate method to compensate for the higher radiation doses measured when a fixed C-arm is used.

AlluraClarity Radiation Dose–Reduction Technology in the Hybrid Operating Room During Endovascular Aneurysm Repair

Purpose: To evaluate the effect of radiation dose reduction with the Allura ClarityIQ image processing technology for fixed C-arms in comparison with a mobile C-arm and an Allura fixed C-arm without ClarityIQ technology during endovascular aneurysm repair (EVAR) procedures. Methods: Radiation dose data from 85 patients (mean age 74.2±7.8 years; 68 men) undergoing EVAR with mobile and fixed C-arm fluoroscopy were retrospectively analyzed. The radiation dose parameters included the kerma area product (KAP), fluoroscopic time (FT), and number of digital subtraction angiography (DSA) frames (FrDSA). KAPtotal consisted of KAPfluoro (KAP for fluoroscopic imaging) and KAPDSA (KAP for DSA and single shots). Linear regression analysis was used to explore differences in the association of KAP with the FT, FrDSA, and body mass index (BMI) among the 3 C-arms. Results: The mean KAPtotal values for mobile, Allura C-arm, and AlluraClarity C-arm for noncomplex EVARs were 56±39, 245±142, and 157±120 Gy·cm2 (p<0.001); for complex EVARs, the values were 110±43, 874±653, and 598±319 Gy·cm2 (p<0.001), respectively. On average, KAPfluoro tripled when the mobile C-arm was replaced by the fixed C-arm. There were no significant differences in the KAPfluoro adjusted for the FT between Allura and AlluraClarity (p=0.69). However, there was a major 61% reduction in KAPDSA from 1.36 Gy·cm2 per DSA frame for Allura to 0.54 Gy·cm2 per DSA frame with AlluraClarity (p=0.03). For the mobile C-arm, BMI was not associated with KAP (p=0.13). The associations of BMI with KAPfluoro and KAPDSA were significant for both fixed C-arms but were more robust for Allura compared to AlluraClarity (p=0.02 for KAPfluoro and p<0.001 for KAPDSA). Conclusion: Changing a mobile C-arm for a fixed C-arm in a hybrid operating suite increased the average intraoperative dose during EVAR. Upgrading the Allura fixed C-arm with ClarityIQ technology resulted in a 61% reduction in the radiation per DSA frame.

[Evaluation of Radiation Dose during Stent-graft Treatment Using a Hybrid Operating Room System]

In recent years, aortic aneurysm treatment with stent graft grafting in the X-ray fluoroscopy is increasing. This is an endovascular therapy, because it is a treatment which includes the risk of radiation damage, having to deal with radiation damage, to know in advance is important. In this study, in order to grasp the trend of exposure stent graft implantation in a hybrid operating room (OR) system, focusing on clinical data (entrance skin dose and fluoroscopy time), was to count the total. In TEVAR and EVAR, fluoroscopy time became 13.40 ± 7.27 minutes, 23.67 ± 11.76 minutes, ESD became 0.87 ± 0.41 mGy, 1.11 ± 0.57 mGy. (fluoroscopy time of EVAR was 2.0 times than TEVAR. DAP of EVAR was 1.2 times than TEVAR.) When using the device, adapted lesions and usage are different. This means that care changes in exposure-related factors. In this study, exposure trends of the stent graft implantation was able to grasp. It can be a helpful way to reduce/optimize the radiation dose in a hybrid OR system.

Radiation exposure to eye lens and operator hands during endovascular procedures in hybrid operating rooms

OBJECTIVE

The purpose of this study was to evaluate the radiation exposure of vascular surgeons' eye lens and fingers during complex endovascular procedures in modern hybrid operating rooms.

METHODS

Prospective, nonrandomized multicenter study design. One hundred seventy-one consecutive patients (138 male; median age, 72.5 years [interquartile range, 65-77 years]) underwent an endovascular procedure in a hybrid operating room between March 2012 and July 2013 in two vascular centers. The dose-area product (DAP), fluoroscopy time, operating time, and amount of contrast dye were registered prospectively. For radiation dose recordings, single-use dosimeters were attached at eye level and to the ring finger of the hand next to the radiation field of the operator for each endovascular procedure. Dose recordings were evaluated by an independent institution. Before the study, precursory investigations were obtained to simulate the radiation dose to eye lens and fingers with an Alderson phantome (RSD, Long Beach, Calif).

RESULTS

Interventions were classified into six treatment categories: endovascular repair of infrarenal abdominal aneurysm (n = 65), thoracic endovascular aortic repair (n = 32), branched endovascular aortic repair for thoracoabdominal aneurysms (n = 17), fenestrated endovascular aortic repair for complex abdominal aortic aneurysm, (n = 25), iliac branched device (n = 8), and peripheral interventions (n = 24). There was a significant correlation in DAP between both lens (P < .01; r = 0.55) and finger (P < .01; r = 0.56) doses. The estimated fluoroscopy time to reach a radiation threshold of 20 mSv/y was 1404.10 minutes (90% confidence limit, 1160, 1650 minutes). According to correlation of the lens dose with the DAP an estimated cumulative DAP of 932,000 mGy/m(2) (90% confidence limit, 822,000, 1,039,000) would be critical for a threshold of 20 mSv/y for the eyes.

CONCLUSIONS

Radiation protection is a serious issue for vascular surgeons because most complex endovascular procedures are delivering measurable radiation to the eyes. With the correlation of the DAP obtained in standard endovascular procedures a critical threshold of 20 mSv/y to the eyes can be predicted and thus an estimate of a potential harmful exposure to the eyes can be obtained.

The use of fenestrated and branched endovascular aneurysm repair for juxtarenal and thoracoabdominal aneurysms: a systematic review and cost-effectiveness analysis

BACKGROUND

Patients with large abdominal aortic aneurysms (AAAs) are usually offered reparative treatment given the high mortality risk. There is uncertainty about how to treat juxtarenal AAAs (JRAAAs) or thoracoabdominal aortic aneurysms (TAAAs). Endovascular repair of an abdominal aortic aneurysm (EVAR) is often seen as safer and easier than open surgical repair (OSR). However, endovascular treatment of JRAAAs or TAAAs requires specially manufactured stent grafts, with openings to allow blood to reach branches of the aorta. Commissioners are receiving increasing requests for fenestrated EVAR (fEVAR) and branched EVAR (bEVAR), but it is unclear whether or not the extra cost of fEVAR or bEVAR is justified by advantages for patients.

OBJECTIVE(S)

To assess the clinical effectiveness, safety and cost-effectiveness of fEVAR and bEVAR in comparison with conventional treatment (i.e. no surgery) or OSR for two populations: JRAAAs and TAAAs.

DATA SOURCES

Resources were searched from inception to October 2013, including MEDLINE (OvidSP), EMBASE (OvidSP) and the Cochrane Central Register of Controlled Trials (Wiley) and, additionally, for cost-effectiveness, NHS Economic Evaluation Database (NHS EED; Wiley) and EconLit (EBSCOhost). Conference abstracts were also searched.

REVIEW METHODS

Studies were included based on an intervention of either fEVAR or bEVAR and a comparator of either OSR or no surgery. For clinical effectiveness, observational studies were excluded only if they were not comparative, i.e. explicitly selected on the basis of prognosis.

RESULTS

For clinical effectiveness, searches retrieved 5253 records before deduplication. Owing to overlap between the databases, 1985 duplicate records were removed. Of the remaining 3268 records, based on titles and abstracts, 3244 records were excluded, leaving 24 publications to be ordered. All 24 studies were excluded as none of them satisfied the inclusion criteria. Sixteen studies were excluded on study design, six on intervention and two on comparator. Five out of 16 studies excluded on study design reported a comparison. However, all of the studies acknowledged that they had groups that were not comparable at baseline given that they had selectively assigned younger, fitter patients to OSR. Therefore, these studies were considered 'non-comparative'. For cost-effectiveness, searches identified 104 references before deduplication. Owing to overlap between the databases, 34 duplicate records were removed. Of the remaining 70 records, seven were included for the full assessment based on initial screening. After a full-text review, no studies were included. Because of the lack of clinical effectiveness evidence and difficulty in estimating costs given the rapidly changing and variable technology, a cost-effectiveness analysis (CEA) was not performed. Instead a detailed description of modelling methods was provided.

CONCLUSIONS

Despite a thorough search, no studies could be found that met the inclusion criteria. All studies that compared either fEVAR or bEVAR with either OSR or no surgery explicitly selected patients based on prognosis, i.e. essentially the populations for each comparator were not the same. Despite not being able to conduct a CEA, we have provided detailed methods for the conduct if data becomes available.

FUTURE WORK

We recommend at least one clinical trial to provide an unbiased estimate of effect for fEVAR/bEVAR compared with OSR or no surgery. This trial should also collect data for a CEA.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013006051.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Radiation-related injuries and their management: an update

Ionizing radiation (in the form of X-rays) is used for the majority of procedures in interventional radiology. This review article aimed at promoting safer use of this tool through a better understanding of radiation dose and radiation effects, and by providing guidance for setting up a quality assurance program. To this end, the authors describe different radiation descriptive quantities and their individual strengths and challenges, as well as the biologic effects of ionizing radiation, including patient-related effects such as tissue reactions (previously known as deterministic effects) and stochastic effects. In this article, the clinical presentation, immediate management, and clinical follow-up of these injuries are also discussed. Tissue reactions are important primarily from the patients' perspective, whereas stochastic effects are most relevant for pediatric patients and from an occupational viewpoint. The factors affecting the likelihood of skin reaction (the most common tissue reaction) are described, and how this condition should be managed is discussed. Setting up a robust quality assurance program around radiation dose is imperative for effective monitoring and reduction of radiation exposure to patients and operators. Recommendations for the pre-, peri-, and postprocedure periods are given, including recommendations for follow-up of high-dose cases. Special conditions such as pregnancy and radiation recall are also discussed.

How accurately can the peak skin dose in fluoroscopy be determined using indirect dose metrics?

PURPOSE

Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that result in skin reactions can be reached during these procedures. There is no consensus as to whether or not indirect skin dosimetry is sufficiently accurate for fluoroscopically-guided interventions. However, measuring PSD with film is difficult and the decision to do so must be madea priori. The purpose of this study was to assess the accuracy of different types of indirect dose estimates and to determine if PSD can be calculated within ± 50% using indirect dose metrics for embolization procedures.

METHODS

PSD were measured directly using radiochromic film for 41 consecutive embolization procedures at two sites. Indirect dose metrics from the procedures were collected, including reference air kerma. Four different estimates of PSD were calculated from the indirect dose metrics and compared along with reference air kerma to the measured PSD for each case. The four indirect estimates included a standard calculation method, the use of detailed information from the radiation dose structured report, and two simplified calculation methods based on the standard method. Indirect dosimetry results were compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the different indirect estimates were examined.

RESULTS

When using the standard calculation method, calculated PSD were within ± 35% for all 41 procedures studied. Calculated PSD were within ± 50% for a simplified method using a single source-to-patient distance for all calculations. Reference air kerma was within ± 50% for all but one procedure. Cases for which reference air kerma or calculated PSD exhibited large (± 35%) differences from the measured PSD were analyzed, and two main causative factors were identified: unusually small or large source-to-patient distances and large contributions to reference air kerma from cone beam computed tomography or acquisition runs acquired at large primary gantry angles. When calculated uncertainty limits [-12.8%, 10%] were applied to directly measured PSD, most indirect PSD estimates remained within ± 50% of the measured PSD.

CONCLUSIONS

Using indirect dose metrics, PSD can be determined within ± 35% for embolization procedures. Reference air kerma can be used without modification to set notification limits and substantial radiation dose levels, provided the displayed reference air kerma is accurate. These results can reasonably be extended to similar procedures, including vascular and interventional oncology. Considering these results, film dosimetry is likely an unnecessary effort for these types of procedures when indirect dose metrics are available.

Anatomic and procedural determinants of fluoroscopy time during elective endovascular aortic aneurysm repair

Objective

To identify both the procedural and anatomic factors which determine duration of fluoroscopy during elective endovascular aortic aneurysm repair (EVAR).

Methods

We retrospectively analyzed our prospectively maintained EVAR database for the relationship between fluoroscopy time and both procedural (type of graft, configuration, number of components, surgeon) and anatomic factors reflective of aneurysm complexity (15 variables).

Results

A total of 128 patients underwent elective EVAR with a mean fluoroscopy time of 5.7 ± 3.4 min. The type of grafts used consisted of 41 (32%) Zenith, 85 (66.4%) Endurant and 2 (1.6%) Anaconda, with 105 (82%) being bifurcated and 23 (18%) being aorto-uni-iliac (AUI) in configuration. Both the surgeon performing the procedure ( p = 0.001) and graft configuration (bifurcated vs. AUI, p = 0.03) were found to be predictive of fluoroscopy time; while procedural and anatomic variables were not.

Conclusions

The surgeon’s efficiency in the use of fluoroscopy during EVAR is the most important determinant of total fluoroscopy time. Anatomic complexity, make of device, and number of components inserted have minimal impact on duration of fluoroscopy. An endovascular surgeon’s ability to curtail fluoroscopy duration is the key component in minimizing radiation exposure to both the surgical team and the patient.

Editor's choice--Angulation of the C-arm during complex endovascular aortic procedures increases radiation exposure to the head

OBJECTIVES/BACKGROUND

The increased complexity of endovascular aortic repair necessitates longer procedural time and higher radiation exposure to the operator, particularly to exposed body parts. The aims were to measure directly exposure to radiation of the bodies and heads of the operating team during endovascular repair of thoracoabdominal aortic aneurysms (TAAA), and to identify factors that may increase exposure.

METHODS

This was a single-centre prospective study. Between October 2013 and July 2014, consecutive elective branched and fenestrated TAAA repairs performed in a hybrid operating room were studied. Electronic dosimeters were used to measure directly radiation exposure to the primary (PO) and assistant (AO) operator in three different areas (under-lead, over-lead, and head). Fluoroscopy and digital subtraction angiography (DSA) acquisition times, C-arm angulation, and PO/AO height were recorded.

RESULTS

Seventeen cases were analysed (Crawford II-IV), with a median operating time of 280 minutes (interquartile range 200-330 minutes). Median age was 76 years (range 71-81 years); median body mass index was 28 kg/m(2) (25-32 kg/m(2)). Stent-grafts incorporated branches only, fenestrations only, or a mixture of branches and fenestrations. A total of 21 branches and 38 fenestrations were cannulated and stented. Head dose was significantly higher in the PO compared with the AO (median 54 μSv [range 24-130 μSv] vs. 15 μSv [range 7-43 μSv], respectively; p = .022), as was over-lead body dose (median 80 μSv [range 37-163 μSv] vs. 32 μSv [range 6-48 μSv], respectively; p = .003). Corresponding under-lead doses were similar between operators (median 4 μSv [range 1-17 μSv] vs. 1 μSv [range 1-3 μSv], respectively; p = .222). Primary operator height, DSA acquisition time in left anterior oblique (LAO) position, and degrees of LAO angulation were independent predictors of PO head dose (p < .05).

CONCLUSIONS

The head is an unprotected area receiving a significant radiation dose during complex endovascular aortic repair. The deleterious effects of exposure to this area are not fully understood. Vascular interventionalists should be cognisant of head exposure increasing with C-arm angulation, and limit this manoeuvre.