Measurement and Optimization of Patient Radiation Doses in Endovascular Aneurysm Repair

Patients' Radiation Exposure During Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

To investigate associations between patient characteristics, intraprocedural complexity factors, and radiation exposure to patients during endovascular abdominal aortic aneurysm repair (EVAR).

METHODS

Elective standard EVAR procedures between January 2015 and December 2020 were retrospectively analyzed. Patient characteristics and intraprocedural data (i.e., type of device, endograft configuration, additional procedures, and contralateral gate cannulation time [CGCT]) were collected. Dose area product (DAP) and fluoroscopy time were considered as measurements of radiation exposure. Furthermore, effective dose (ED) and doses to internal organs were calculated using PCXMC 2.0 software. Descriptive statistics, univariable, and multivariable linear regression were applied to investigate predictors of increased radiation exposure.

RESULTS

The 99 patients were mostly male (90.9%) with a mean age of 74 ± 7 years. EVAR indications were most frequently abdominal aortic aneurysm (93.9%), penetrating aortic ulceration (2.0%), focal dissection (2.0%), or subacute rupture of infrarenal abdominal aortic aneurysm (2.0%). Median fluoroscopy time was 19.6 minutes (interquartile range [IQR], 14.1-29.4) and median DAP was 86,311 mGy cm2 (IQR, 60,160-130,385). Median ED was 23.2 mSv (IQR, 17.0-34.8) for 93 patients (93.9%). DAP and ED were positively correlated with body mass index (BMI) and CGCT. Kidneys, small intestine, active bone marrow, colon, and stomach were the organs that received the highest equivalent doses during EVAR. Higher DAP and ED values were observed using the Excluder endograft, other bi- and tri-modular endografts, and EVAR with ≥2 additional procedures. Multivariable linear regression analysis revealed that BMI, ≥2 additional procedures during EVAR, and CGCT were independent positive predictors of DAP and ED levels after accounting for endograft type.

CONCLUSIONS

Patient-related and procedure-related factors such as BMI, ≥2 additional procedures during EVAR, and CGCT resulted predictors of radiation exposure for patients undergoing EVAR, as quantified by higher DAP and ED levels. The main intraprocedural factor that increased radiation exposure was CGCT. These data can be of importance for better managing radiation exposure during EVAR.

BMI-Based organ doses in endovascular aneurysm repair interventions utilising Monte Carlo simulation

In this study, the effect of body-mass-index (BMI) on organ doses (ODs) during infrarenal endovascular-aneurysm-repair (EVAR) procedures was evaluated. Patient- and intra-operative data from fifty-nine EVAR procedures were inserted into VirtualDose-IR software to calculate ODs. For overweight, obesity class-I and obesity class-II, ODs were up to 147%, 412% and 775% higher than those for normal weight-patients, respectively. A large variation was observed in ODs published in literature mainly due to the differences in the software and the technical parameters used for the calculations.

A novel personalized dosimetry method for endovascular aneurysm repair (EVAR) procedures

OBJECTIVE

To estimate radiation doses for the primarily irradiated organs/tissues of patients subjected to standard endovascular aneurysm repair (EVAR) procedures using a novel personalized dosimetry method.

METHODS

Dosimetric and anthropometric data were collected prospectively for eight patients who underwent standard EVAR procedures. Patient-specific Monte Carlo simulations were performed to estimate organ/tissue doses from each of the fluoroscopic and digital subtraction angiography acquisitions involved in EVAR. Individual-specific cumulative absorbed doses were estimated for the skin, spinal bone marrow, heart, kidneys, liver, colon, bladder, pancreas, stomach, and spleen and compared to corresponding values estimated through a commercially available dosimetric software package that employs standardized phantoms.

RESULTS

The highest organ/tissue radiation doses from EVAR were found for the skin, spinal bone marrow, kidneys, and spleen as 192.4 mGy, 96.7 mGy, 72.9 mGy, and 33.6 mGy respectively, while the doses to the heart, liver, colon, bladder, pancreas, and stomach were 6.3 mGy, 14.4 mGy, 18.4 mGy, 14.8 mGy, 21.6 mGy, and 11.2 mGy respectively. Corresponding dose values using standardized phantoms were found to differ up to 151%.

CONCLUSION

Considerable radiation doses may be received by primarily exposed organs/tissues during standard EVAR. The specific size/anatomy of the patient and the variation in exposure parameters/beam angulation between different projections commonly involved in EVAR procedures should be taken into account if reliable organ dose data are to be derived.

KEY POINTS

• A novel patient-specific dosimetry method was utilized to estimate radiation doses to the primarily irradiated organs/tissues of patients subjected to standard endovascular aneurysm repair procedures. • The use of standardized mathematical anthropomorphic phantoms to derive organ dose from fluoroscopically guided procedures may result in considerable inaccuracies due to differences in the assumed organ position/volume/shape compared to patients.

Factors affecting radiation exposure in endovascular repair of abdominal aortic aneurysms: a pilot study

BACKGROUND

Radiation exposure during endovascular repair (EVAR) of abdominal aortic aneurysms (AAAs) is a potential issue. Several studies have identified factors affecting radiation exposure, although they are limited. The aim of this study was to identify independent factors affecting radiation exposure in patients with AAA undergoing standard EVAR.

METHODS

Forty-eight consecutive patients underwent elective EVAR for infrarenal AAA managed between April 2019 and April 2020. Fluoroscopy time (FT) and kerma area product (KAP) were the main outcome measures.

RESULTS

Median (interquartile range) FT and KAP values were 1018 (653-1619) s and 2.68 (2.08-3.81) mGy·m², respectively. C3 Excluder graft use and main body insertion site from the right femoral were associated with significantly lower FT. Coronary artery disease, endografts with two docking limbs, AAA diameter, neck angle and length, procedure duration, contrast amount, and hospitalization were associated with significantly higher FT. Neck angle was the single independent perioperative factor related to FT higher than the median value observed in the study (P=0.004, odds ratio: 1.073, 95% confidence interval: 1.023-1.126). The use of the C3 Excluder device was associated with lower KAP. AAA diameter, neck angle, procedure duration, contrast medium amount and postoperative hospitalization were associated with higher KAP. AAA diameter was the single independent factor related to KAP higher than the median value observed in the study (P=0.013, odds ratio: 3.73, 95% confidence interval: 1.32-10.56).

CONCLUSIONS

This study has identified factors affecting radiation exposure during standard EVAR for infrarenal AAAs. These factors should be taken into account when contemplating AAA repair.

Patient radiation dose from x-ray guided endovascular aneurysm repair: a Monte Carlo approach using voxel phantoms and detailed exposure information

Endovascular aneurysm repair (EVAR) is a well-established minimally invasive technique that relies on x-ray guidance to introduce a stent through the femoral artery and manipulate it into place. The aim of this study was to estimate patient organ and effective doses from EVAR procedures using anatomically realistic computational phantoms and detailed exposure information from radiation dose structured reports (RDSR). Methods: Lookup tables of conversion factors relating kerma area product (P_KA) to organ doses for 49 different beam angles were produced using Monte Carlo simulations (MCNPX2.7) with International Commission on Radiological Protection (ICRP) adult male and female voxel phantoms for EVAR procedures of varying complexity (infra-renal, fenestrated/branched and thoracic EVAR). Beam angle specific correction factors were calculated to adjust doses according to x-ray energy. A MATLAB function was written to find the appropriate conversion factor in the lookup table for each exposure described in the RDSR, perform energy corrections and multiply by the respective exposure P_KA. Using this approach, organ doses were estimated for 183 EVAR procedures in which RDSRs were available. A number of simplified dose estimation methodologies were also investigated for situations in which RDSR data are not available. Results: Mean estimated bone marrow doses were 57 (range: 2-247), 86 (2-328) and 54 (8-250) mGy for infra-renal, fenestrated/branched and thoracic EVAR, respectively. Respective effective doses were 27 (1-208), 54 (1-180) and 37 (5-167) mSv. Dose estimates using non-individualised, average conversion factors, along with those produced using the alternative Monte Carlo code PCXMC, yielded reasonably similar results overall, though variation for individual procedures could exceed 100% for some organs. In conclusion, radiation doses from x-ray guided endovascular aneurysm repairs are potentially high, though this must be placed in the context of the life sparing nature and high success rate for this procedure.

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.

Radiation exposure in an endovascular aortic aneurysm repair program after introduction of a hybrid operating theater

BACKGROUND

A hybrid operating theater (HOT) enables optimal image quality, improved ergonomics, and excellent sterility for complex endovascular and hybrid procedures. We hypothesize that the commissioning of a new HOT involves a learning curve. It is unclear how steep the learning curve of these advanced HOTs is. The main purpose of this research was to evaluate radiation exposure parameters in a new HOT for a team of vascular surgeons experienced with infrarenal endovascular aneurysm repair (EVAR) procedures in a conventional operating room with a mobile C-arm. In addition, a comparison of the dose-area product (DAP) achieved in this study and in the literature was made.

METHODS

Before commissioning of the HOT, four vascular surgeons completed a comprehensive HOT training program. From the commissioning of the HOT, clinical and procedural data for all consecutive acute and elective patients treated with EVAR were retrospectively collected for a period of 18 months (January 2016-June 2017). A literature review was conducted of the dose-area product in EVAR procedures performed with a dedicated fixed system or mobile C-arm to analyze how this study performed compared with the literature.

RESULTS

In the 18-month study period, 77 patients were treated with EVAR (59 electively and 18 acutely), from whom the data were obtained. There was no significant change in radiation exposure parameters over time. From the commissioning of the HOT, EVAR procedures were performed with radiation exposure parameters similar to those of studies found in experienced vascular centers using fixed systems.

CONCLUSIONS

Concerning radiation exposure parameters, the commissioning of a new HOT was not accompanied by a learning curve. Radiation exposure parameters achieved in this study were similar to those of studies from experienced and dedicated vascular centers.

Challenges assessing radiation risk in image-guided treatments-implications on optimisation of radiological protection

The present work explores challenges when assessing organ dose and effective dose concerning image-guided treatments. During these treatments considerable x-ray imaging is employed using technically advanced angiographic x-ray equipment. Thus, the radiation dose to organs and the related radiation risk are relatively difficult to assess. This has implications on the optimisation process, in which assessing radiation dose is one important part. In this study, endovascular aortic repair treatments were investigated. Organ dose and effective dose were assessed using Monte Carlo calculations together with a detailed specification of the exposure situation and patient size. The resulting normalised organ dose and effective dose with respect to kerma-area product for patient sizes and radiation qualities representative for the patient group were evaluated. The variability and uncertainty were investigated and their possible impact on optimisation of radiation protection was discussed. Exposure parameters, source to detector distances etc varied between treatments and also varied between image acquisitions during one treatment. Thus the derived normalised organ dose and effective dose exhibited a large range of values depending greatly on used exposure parameters and patient configuration. The derived normalised values for effective dose varied approximately between 0.05 and 0.30 mSv per Gy·cm² when taking patient sizes and exposure parameters into consideration, the values for organ doses exhibited even larger variation. The study shows a possible systematic error for derived organ doses and effective dose up to a factor of 7 if detailed exposure or patient characteristics are not known and/or not taken into consideration. The intra-treatment variability was also substantial and the normalised dose values varied up to a factor of 2 between image acquisitions during one treatment. The study shows that the use of conversion factors that are not adapted to the clinic can cause the radiation dose to be exaggerated or underestimated considerably. A conclusion from the present study is that the systematic error could be large and should be estimated together with random errors. A large uncertainty makes it difficult to detect true differences in radiation dose between methods and technology-a prerequisite for optimising radiation protection for image-guided treatments.

Patient doses in endovascular and hybrid revascularization of the lower extremities

OBJECTIVE:

Hybrid surgical methods such as remote endarterectomy and endovascular revascularization are fluoroscopy-guided procedures successfully replacing conventional open surgery for treatment of peripheral artery disease (PAD). The aim of this study was to: (1) evaluate the dose parameters describing exposure of patients undergoing endovascular or hybrid revascularization of the lower limb (below the inguinal ligament); (2) compare the data available in the literature with the evaluations of patients' dose values and related factors for patients undergoing such procedures; (3) examine the correlation of doses with certain parameters; (4) estimate the peak skin dose and assess the potential for radiation-induced skin injuries during the procedures.

METHODS:

Data for 259 patients were extracted retrospectively and analyzed. The procedures were grouped by type of intervention, vascular approach, and level of complexity. The analyses included the correlation of dose values with the operating team.

RESULTS:

The air kerma-area product (KAP) and fluoroscopy time (FT) values greatly varied depending on the procedure type but also among patients undergoing the same procedure. The type of vascular access has the largest impact on patients' doses. The KAP and FT values for brachial artery were: 347 Gy.cm² and FT: NA; for contralateral common femoral artery (CFA) approach: 207 Gy.cm² and 153 s; e.g. significantly higher than for ipsilateral CFA: 96 Gy.cm² and 78 s; for hybrid surgery: 77 Gy.cm² and 41 s; and for ipsilateral retrograde popliteal approach: 61 Gy.cm² and 53 s. The same tendency is observed for the peak skin dose (PSD) values: the highest are for brachial artery (2053 mGy) and contralateral CFA (1325 mGy) approach, followed by the ipsilateral CFA (748 mGy), hybrid surgery (649 mGy), and ipsilateral retrograde popliteal approach (566 mGy).

CONCLUSION:

Registered dose values and FT for the different procedures do not exceed the International Atomic Energy Agency (IAEA) proposed trigger values for patients' follow-up for radiation-induced skin injuries. The type of vascular access has the highest negative impact on radiation dose levels and resultant KAP, PSD, and FT values. There is a significant increase of the dose values with increase of the number of inserted stents and the level of complexity. This should be considered in planning, especially for patients who undergo multiple diagnostic and therapeutic procedures.

ADVANCES IN KNOWLEDGE:

This study gives a systematic understanding for patient radiation exposure in endovascular and hybrid revascularization of the lower extremities, thus far absent in the literature.

Incidental extravascular findings in computed tomographic angiography for planning or monitoring endovascular aortic aneurysm repair: Smoker patients, increased lung cancer prevalence?

AIM

To validate the feasibility of high resolution computed tomography (HRCT) of the lung prior to computed tomography angiography (CTA) in assessing incidental thoracic findings during endovascular aortic aneurysm repair (EVAR) planning or follow-up.

METHODS

We conducted a retrospective study among 181 patients (143 men, mean age 71 years, range 50-94) referred to our centre for CTA EVAR planning or follow-up. HRCT and CTA were performed before or after 1 or 12 mo respectively to EVAR in all patients. All HRCT examinations were reviewed by two radiologists with 15 and 8 years’ experience in thoracic imaging. The results were compared with histology, bronchoscopy or follow-up HRCT in 12, 8 and 82 nodules respectively.

RESULTS

There were a total of 102 suspected nodules in 92 HRCT examinations, with a mean of 1.79 nodules per patient and an average diameter of 9.2 mm (range 4-56 mm). Eighty-nine out of 181 HRCTs resulted negative for the presence of suspected nodules with a mean smoking history of 10 pack-years (p-y, range 5-18 p-y). Eighty-two out of 102 (76.4%) of the nodules met criteria for computed tomography follow-up, to exclude the malignant evolution. Of the remaining 20 nodules, 10 out of 20 (50%) nodules, suspected for malignancy, underwent biopsy and then surgical intervention that confirmed the neoplastic nature: 4 (20%) adenocarcinomas, 4 (20%) squamous cell carcinomas, 1 (5%) small cell lung cancer and 1 (5%) breast cancer metastasis); 8 out of 20 (40%) underwent bronchoscopy (8 pneumonia) and 2 out of 20 (10%) underwent biopsy with the diagnosis of sarcoidosis.

CONCLUSION

HRCT in EVAR planning and follow-up allows to correctly identify patients requiring additional treatments, especially in case of lung cancer.

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.

Radiation exposure in patients treated with endovascular aneurysm repair: what is the risk of cancer, and can we justify treating younger patients?

Background Endovascular aneurysm repair (EVAR) is becoming the mainstay treatment of abdominal aortic aneurisms (AAA). The postoperative follow-up regime includes a lifelong series of CT angiograms (CTAs) at different intervals in addition to EVAR, which will confer significant cumulative radiation exposure over time. Purpose To examine the impact of age and follow-up regime over time on cumulative radiation exposure and attributable cancer risk after EVAR. Material and Methods We calculated a mean effective dose (ED) for the EVAR procedure, CTA, and plain abdominal X-rays (PAX). Cumulative ED was calculated for standard, complex, and simplified surveillance over 5, 10, and 15 years for different age groups. Results For EVAR, the mean ED was 34 mSv (range, 12-75 mSv) per procedure. For PAX, the ED was 1.1 mSv (range, 0.3-4.4 mSv), and for CTA it was 8.0 mSv (range, 2-20 mSv). For a 55-year-old man, an attributable cancer risk (ACR) in standard surveillance at 5 and 15 years of follow-up was 0.35% and 0.65%, respectively. The corresponding values were 0.22% and 0.37% for a 75-year-old man. When using a simplified follow-up, the ACRs for a 55-year-old at 5 and 15 years were 0.30% and 0.37%, respectively. These values were 0.18% and 0.21% for a 75-year-old man. A complex follow-up with half-yearly CTA over similar age and time span doubled the ACR. Conclusion Treating younger patients with EVAR poses a low ACR of 0.65% (15-year standard surveillance) compared to a lifetime cancer risk of 44%. A simplified surveillance should be used if treating younger patients, which will halve the ACR over 15 years.

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.

Radiation delivered to patients during endourological surgery – are they overexposed?

Introduction:

Ionising radiation is commonly used in urological practice in the form of fluoroscopy. To date there is a remarkable scarcity of information concerning patient exposure to ionising radiation during urological procedures and the potential risk of developing of a lethal malignancy due to excessive radiation exposure.

Objectives:

We aimed to determine the radiation exposure for a patient during the most commonly performed urological procedures, and to assess the potential risk of developing a fatal cancer as a result of endourological fluoroscopy.

Methods:

Data was collected prospectively in two institutions on endoscopic urological operations. Procedures were classified as retrographic, semi-rigid ureteroscopic and flexible ureterorenoscopic (FURS). Data collected included procedure type and difficulty, Dose Area Product [DAP (Gy*Cm2)]. The effective dose (ED) measured in millisievert (mSv) was determined from the DAP by using the Monte Carlo calculation.

Results:

In total 395 consecutive operations from two institutions were assessed. The mean ED for all procedures in this study was 0.394 mSv, IQR (0.1184–0.7583). The maximum ED was 5.93 mSv. The radiation exposure for all procedures was relatively small; for diagnostic retrographic procedures the median ED was 0.112 mSv. For retrograde procedures that involved stent insertion, the median ED was 0.438 mSv. The median ED for all ureteroscopic surgeries was 0.295 mSv, and the median ED for all FURS procedures was 0.491.

Conclusion:

The findings of this study are reassuring. Endoscopic urological procedures appear to expose patients to relatively small radiation compared with other procedures requiring fluoroscopy, thus conferring a very low lifetime risk of malignancy.

Typical exposure parameters, organ doses and effective doses for endovascular aortic aneurysm repair: Comparison of Monte Carlo simulations and direct measurements with an anthropomorphic phantom

OBJECTIVES

Radiation exposure of patients during endovascular aneurysm repair (EVAR) procedures ranks in the upper sector of medical exposure. Thus, estimation of radiation doses achieved during EVAR is of great importance.

MATERIAL AND METHODS

Organ doses (OD) and effective doses (ED) administered to 17 patients receiving EVAR were determined (1) from the exposure parameters by performing Monte Carlo simulations in mathematical phantoms and (2) by measurements with thermoluminescent dosimeters in a physical anthropomorphic phantom.

RESULTS

The mean fluoroscopy time was 26 min, the mean dose area product was 24995 cGy cm2. The mean ED was 34.8 mSv, ODs up to 626 mSv were found. Whereas digital subtraction angiographies (DSA) and fluoroscopies each contributed about 50% to the cumulative ED, the ED rates of DSAs were found to be ten times higher than those of fluoroscopies. Doubling of the field size caused an ED rate enhancement up to a factor of 3.

CONCLUSION

EVAR procedures cause high radiation exposure levels that exceed the values published thus far. As a consequence, (1) DSAs should be only performed when necessary and with a low image rate, (2) fluoroscopies should be kept as short as possible, and (3) field sizes should be minimized.

KEY POINTS

• During endovascular aneurysm repair (EVAR) considerable patient doses are achieved. • For each EVAR procedure organ (OD) and effective (ED) doses were determined. • The mean ED was 34.8 mSv, the highest OD was 626 mSv. • Number of DSAs, fluoroscopy durations and field sizes should be minimized.

A comparison study of radiation exposure to patients during EVAR and Dyna CT in an angiosuite vs. an operating theatre

The aim of this study was to assess the patient dosimetric impact of endovascular abdominal aortic aneurysm repair (EVAR), both in an operating theatre (OR) and in an angiosuite (AS), with the facility of Dynamic CT (Dyna CT, Siemens AG, Berlin, Germany). One hundred and forty-six consecutive EVAR procedures dating from May 2011 to March 2013 were analysed. These were performed either in an OR (n = 97) using a mobile C-arm or in an AS (n = 49) equipped with a ceiling-mounted angiography system. Air kerma area product (P(KA)) and total air kerma at reference point (K(a,r)) values were reported for all procedures and Dyna CT. Radiation exposure during EVAR was quite low in the majority of patients but nearly 50 % higher if performed in AS vs. OR. Median Dyna CT K(a,r) was the same as an entire EVAR procedure in OR. The higher patient's radiation exposure recorded in the AS should be balanced with the technical advantages given to the EVAR procedure.

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.

Review of the Use of Ionizing Radiation in Endovascular Aneurysm Repair

Endovascular repair for aortic aneurysm (EVAR) is rapidly increasing in popularity. The nature of this intervention requires significant exposure to ionizing radiation both during the procedure and for postoperative surveillance, generally in the form of computed tomography. Here the authors review the literature for radiation exposure during EVAR, both for the patient and the physician.