Operator-controlled Imaging Significantly Reduces Radiation Exposure during
G. Peach*, S. Sinha, S.A. Black, R.A. Morgan, I.M. Loftus, M.M. Thompson, R.J. Hinchliffe
St George’s Vascular Institute, 4th Floor, St James Wing, St George’s Healthcare NHS Trust, Blackshaw Road, London SW17 0QT, UK
WHAT THIS PAPER ADDS
? This study presents data from a contemporary series of patients undergoing EVAR and demonstrates that changing to operator-
controlled imaging is a useful and achievable method of improving safety and efficiency during EVAR.
a r t i c l e i n f o
Received 22 May 2012
Accepted 1 August 2012
Available online 22 August 2012
a b s t r a c t
Introduction: Adoption of endovascular aneurysm repair (EVAR) has led to significant reductions in the
short-term morbidity and mortality associated with abdominal aortic aneurysm (AAA) repair. However,
EVAR may expose both patient and interventionalist to potentially harmful levels of radiation, particu-
larly as more complex procedures are undertaken. The aim of this study was to assess whether changing
from radiographer-controlled imaging to a system of operator-controlled imaging (OCI) would influence
radiation exposure, screening time or contrast dose during EVAR.
Method: Retrospective analysis identified patients that had undergone elective EVAR for infra-renal AAA
before or after the change to operator-controlled imaging. Data were collected for radiation dose
(measured as dose area product; DAP), screening time, total delivered contrast volume and operative
duration. Data were also collected for maximum aneurysm diameter, patient age, gender and body mass
Results: 122 patients underwent EVAR for infra-renal AAA at a single centre between January 2011 and
December 2011. 57 of these were prior to installation of OCI and 65 after installation. Median DAP was
significantly lower after installation of OCI (4.9 mGy m2; range 1.25e13.3) than it had been before
installation (6.9 mGy m2; range 1.91e95.0) (p ¼ 0.005). Median screening times before and after
installation of OCI were 20.0 min and 16.2 min respectively (p ¼ 0.027) and median contrast volumes
before and after the change to OCI were 100 ml and 90 ml respectively (p ¼ 0.21).
Conclusion: Introduction of operator-controlled imaging can significantly reduce radiation exposure
during EVAR, with particular reduction in the number of ‘higher-dose’ cases.
? 2012 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
Over the past two decades, endovascular repair (EVAR) has
become widely accepted as a safe and effective alternative to open
repair (OR) for the treatment of abdominal aortic aneurysms (AAA).
Whilst this technique has brought with it significant reductions in
short-term morbidity and mortality, it has also led to concerns
about the degree to which both patient and interventionalist (i.e.
surgeon or interventional radiologist) are exposed to radiation
during treatment and follow-up. Efforts toreduce the postoperative
radiation burden have seen a progressive shift towards duplex
ultrasound for graft surveillance rather than repeated computed
tomography (CT).1As a result, concerns about the amount of radi-
ation delivered to patients are increasingly focused on intra-
operative exposure. This is particularly relevant as operators
become more skilled and are undertaking increasingly complex
procedures that necessitate prolonged fluoroscopic imaging.
The potential significance of radiation exposure is well recog-
nized in other radiographic procedures2and effects can be classi-
fied as either deterministic (causing direct tissue damage) or
* Corresponding author. Tel.: þ44 (0) 2087253214; fax: þ44 (0) 2087253495.
E-mail address: email@example.com (G. Peach).
Contents lists available at SciVerse ScienceDirect
European Journal of Vascular and Endovascular Surgery
journal homepage: www.ejves.com
1078-5884/$ e see front matter ? 2012 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
European Journal of Vascular and Endovascular Surgery 44 (2012) 395e398
stochastic (inducing gene mutation). It has previously been sug-
gested that radiation exposure may reach a level that is theoreti-
cally sufficient to cause deterministic effects in up to 30% of EVAR
cases.3,4However, whilst deterministic effects have often been re-
ported during coronary angiography,5reports of direct radiation
damage during EVAR are scarce.6,7This may be due to a paucity of
radiation data relating to EVAR, the result of the frequent change in
focal point during this procedure, or more likely, the non-reporting
of patient radiation injuries.
While a number of authors have assessed the level of radiation
exposure during EVAR,3,8,9few have explicitly examined ways in
which this exposure might be reduced. This study used a planned
change in theatre configuration to assess whether changing to
a system of operator-controlled imaging (OCI) would influence
radiation exposure, operative duration, screening time, or contrast
dose during EVAR.
Datawere collected retrospectively for consecutive patients that
underwent elective EVAR for infra-renal AAA at a single centre
between January 2011 and December 2011. This time period was
chosen to provide data from patients both before and after
conversion to OCI, which occurred on 29th June 2011. Patients who
underwent more complex forms of endografting, such as thoracic,
fenestrated, or iliac-branch grafts were excluded, as were patients
who underwent insertion of aortouniiliac endografts (AUI), in order
tominimize morphological heterogeneity. Patients who underwent
EVAR solely for the treatment of iliac artery aneurysm were also
excluded, whilst those with both AAA and iliac aneurysm were
included, since variations in iliac size are common and were not
considered likely to significantly confound the data.
The variables of primary interest were: Intraoperative radiation
dose expressed as dose area product (DAP in mGy m2); delivered
contrast medium volume (ml); overall screening time and opera-
tive duration. Data were also collected for the individual operators,
maximum aneurysm diameter and patient age, gender and body
mass index (BMI). All data were gathered from theatre logbooks,
Picture Archiving and Communication System (PACS), patient case-
notes and Electronic Patient Records (EPR).
All procedures were performed in a single operating theatre by
a consultant vascular interventionalist experienced in EVAR or
a final-year trainee under consultant supervision. Prior to June 29th
2011, proceduralimaging was performed using an OEC 9800 Mobile
C-arm (GE Medical Systems, Utah, USA), with a standard, static,
radiolucent theatre table. For procedures after 29th June 2011,
imaging was carried out using an OEC 9900 MD Elite (Vascular)
Mobile C-arm (GE Medical Systems, Utah, USA), with a Stille ImagiQ
cardiovascular table (Stille-Sonesta Inc., Texas, USA) and multiple
video output screens on a NuBoom articulating support (GE
Medical Systems, Utah, USA). The new imaging system is operated
via a sterile, tableside control panel that gives the interventionalist
precise, fully motorized control of the C-arm, patient position and
imaging mode. Though image acquisition is the same resolution on
old and new systems, high definition video output screens also
offer improved anatomical visualization.
Low-dose fluoroscopy and high-dose ‘digital acquisition’ were
performed using pulse-beam fluoroscopy at 12 frames per second.
throughout the study period and was via a Medrad Mark V Plus
angiographic injector (Medrad UK Ltd., Ely, UK).
DAP was recorded by transmission ionization chambers integral
to both old and new C-arms. These were calibrated according to
manufacturers instructions. Screening time was also recorded
automatically by the software in both old and new C-arms. The
time recorded was a combined total for low-dose fluoroscopy and
high-dose digital-acquisition. Contrast medium volume was docu-
mented as the total volume delivered throughout the procedure.
All patients underwent preoperative CT-scanning to assess
aneurysm morphology and cases were planned using 3mensio
Vascular? software (3mensio Medical Imaging BV, Bilthoven,
Netherlands). Other than the change to OCI, there was no change in
operative protocol during the study period, nor any additional
training with regard to radiation safety (that might have influenced
the dose delivered by the operator).
122 patients underwent elective EVAR for infra-renal AAA
between 4th January 2011 and 17th December 2011. Of these, 57
patients had their intervention prior to installation of OCI and 65
patients underwent EVAR after installation of OCI. Mean values for
age, BMI, and maximum aneurysm diameter were not significantly
different before and after the change in theatre configuration. The
male/female ratio was also unchanged (Table 1).
Median DAP values before and after change in theatre configu-
ration were 6.9 mGy m2and 4.9 mGy m2respectively, representing
a 29% reduction in median emitted radiation dose (p ¼ 0.005).
Notably, the range of values was far greater prior to the introduc-
tion of OCI, with DAP values exceeding 23.5 mGy cm2in 9 of 57
cases. After introduction of the new system, the highest recorded
DAP was 13.3 mGy m2(Table 2).
Median total screening time was also significantly lower after
installation of OCI (16.2 min) than before installation (20.0 min)
(p ¼ 0.027), though there was no significant correlation between
total screening time and DAP (r ¼ 0.13). Operative durationwas also
reduced following the change to OCI (130 min before; 120 min
after), as was contrast dose (100 ml before; 90 ml after), but both of
these were non-significant (p ¼ 0.28 and p ¼ 0.21 respectively)
Consultant interventionalists performed the majority of cases
both before (65%) and after (62%) installation of OCI.
Zenith?endografts (Cook Medical Inc., Bloomington, USA) were
the most frequently used device both before (n ¼ 40) and after
(n ¼ 49) the change to OCI. All remaining cases were performed
using Endurant? devices (Medtronic, Minneapolis, USA).
Exposure to radiation is an undesirable yet inevitable conse-
quence of all fluoroscopic procedures, particularly those that
authors have attempted to quantify the level of radiation exposure
during EVAR3,8,9little work has been done to assess whether more
of OCI (SD) n ¼ 57
of OCI (SD) n ¼ 65
Mean age (yrs)
Gender (n ¼ male/n
Mean Body Mass Indexa
an ¼ 48(before)/45(after).
cp-value based on Fisher’s exact test.
G. Peach et al. / European Journal of Vascular and Endovascular Surgery 44 (2012) 395e398
modest changes in operative protocol and theatre configuration
could reduce radiation exposure for both patient and surgeon.
Radiation levels recorded during this study were in keeping
with those reported elsewhere, with median DAP values after
installation of OCI being comparable to the optimum series in the
literature.8,10,11Whilst DAP does not provide a direct measure of
absolute radiation dose received by the patient or interventionalist,
it has been shown to have a strong correlation with peak skin dose
(PSD) during EVAR (r2¼ 0.923).10,11PSD is a direct measurement of
radiation dose derived from radiochromic films placed beneath the
patient throughout the procedure. This strong correlation therefore
supports the use of DAP as a surrogate measure of received radia-
tion dose. Furthermore, whilst entrance skin dose (ESD) or effective
dose (ED) are often reported for angiographic procedures, both of
these alternative measures are dependent upon the position of the
X-ray tube relative to the patient. Since this relative position varies
so significantly during EVAR, DAP was considered to be the most
useful surrogate of radiation exposure in this setting.
What is most notable from our results is that the change to OCI
not only reduced median DAP, but also dramatically reduced the
range of DAP values observed (Fig. 1). Prior to introduction of OCI,
the range of DAP values was 1.9e95.0 mGy m2(with only a single
DAP value over 78.3 mGy m2), which is broadly similar to figures
presented by Kuhelj et al. and Weerakoddy et al., who observed
ranges of 3.5e70 mGy2m2and 9e66 mGy m2respectively.3,7After
installation of OCI, however, the maximum recorded DAP during 65
consecutive cases was only 13.3 mGy m2, which is lower than the
maximum recorded DAP in any series of bifurcated endografts
published to date.8,10,12
Scrutinyof the nine cases inwhich DAP exceeded 20 mGy m2(all
prior to OCI) did not reveal any clear intraoperative difficulty, nor
any significant differences in BMI, gender, maximum aneurysm
diameter or type of endograft compared to patients who received
lower radiation doses. The mean age of these higher-dose patients
was greater than in the low-dose group (80.1 yrs versus 76.6 yrs),
but this alone does not explain the dose differences. Operator
inexperience was also excluded as a sole cause of higher radiation
exposure, since six of the nine higher-dose cases were performed
by consultant interventionalists (which is in keeping with the total
proportion of cases performed by consultants). Furthermore, the
same group of interventionalists performed the majority of
procedures both before and after the change to OCI, confirming that
reduced DAP values were not simply the result of change in
This reduction in maximum delivered dose is particularly rele-
vant in attempts to reduce the impact of radiation on patients.
Whilst mean/median DAP values give a useful guide to likely
cumulative exposure for the interventionalist, it is the cases at the
upper end of the dose range that are most likely to result in
deterministic effects for the patient. Since a significant proportion
of patients undergoing EVAR may exceed the theoretical threshold
for deterministic tissue damage,3every effort must be made to
reduce the number of these ‘high-dose’ cases.
In contrast to other authors,13e15our results showed no corre-
lation between DAP and overall screening time (i.e. low-dose
fluoroscopy and high-dose digital acquisition combined) or BMI.
Nor was there any correlation between DAP and the volume of
contrast used. Whilst median DAP was reduced by nearly 30%
following introduction of OCI, there was only a 19% fall in overall
screening time (p ¼ 0.027) and a 10% reduction in contrast dose
(p ¼ 0.28). This suggests that there was a reduction in the number
or duration of high-dose digital acquisition ‘runs’ after introduction
of OCI, since this would significantly reduce DAP whilst having
relatively little effect on overall screening time. This may be
because OCI provides improved anatomical clarity by allowing the
operator to position the patient more accurately before performing
high-dose ‘runs’, thereby limiting the number/length of runs
necessary to assess graft position during deployment. Prospective
data collection would be necessary to confirm these assertions
since this was a retrospective study and number and length of runs
were not routinely recorded.
Although high-dose cases may be responsible for possible
deterministic effects, the risk of stochastic effects e and the need to
reduce routine radiation exposure e should not be underestimated.
It has been suggested that the lifetime fatal-cancer risk may be
greater than 1% for patients undergoing EVAR,16and whilst some
patients may be veryelderly and not live long enough for stochastic
effects to manifest (typically 10e20 yrs),17,18the introduction of
AAA screening programmes has meant that increasing numbers of
patients are being treated at 65e70 yrs of age. In addition, thoracic
endografts are now being used with increasing frequency to treat
young trauma patients who will require life-long surveillance. The
risk of stochastic effects must therefore be minimized whenever
The low DAP values and reduced screening times achieved in
this study demonstrate that interventionalists working in adapted
operating theatres can enhance the safetyand efficiency of EVAR by
changing to OCI. This technique not only reduces radiation expo-
sure to both patient and interventionalist, but also implies that
fewer staff are required to perform the procedure e a factor
particularly beneficial in the emergency setting when availability of
staff is often low. Although these results were achieved with
a mobile C-arm, it is likely that future progression to full-hybrid
theatres with fixed, high-quality imaging under operator control
may offer further improvements in performance.
With increasing evidence that EVAR can be performed with
consistently low radiation doses, it may also be feasible to establish
clearer guidelines for acceptable exposure during this procedure
and ensure that it is ‘as low as reasonably practicable’ (ALARP).19
Though there will always be a balance between image quality
and radiation dose, greater awareness of the issues would allow
Figure 1. Radiation exposure in cases before/after change to OCI.
Median values before and after change to OCI.
before OCI (range)
with OCI (range)
Dose area product
Screening time (min)
Contrast dose (ml)a
Operative duration (min)
6.9 (1.91e95.0) 4.9 (1.25e13.3) 0.005
an ¼ 45(before)/51(after).
bMann-Whitney U test.
G. Peach et al. / European Journal of Vascular and Endovascular Surgery 44 (2012) 395e398
interventionalists to monitor radiation levels just as they monitor Download full-text
other operative outcomes and ensure high doses are not being
Operator-controlled imaging allows surgeons and interven-
tional radiologists to perform EVAR with greater independence
while significantly reducing the delivered radiation dose. Further
data are necessary to verify whether changing to OCI is sufficient to
completelyeliminate ‘high-dose’ cases during infra-renal EVAR and
clarify whether similar improvements can be achieved in the
treatment of more complex aneurysms.
Conflict of Interest
We would like to acknowledge the valuable contributions of Ms
S Nayak and Ms T Wieder during the preparation of this
Thompson MM, et al. Heterogeneity in surveillance after endovascular aneu-
rysm repair in the UK. Eur J Vasc Endovasc Surg 2011:585e90.
2 Marx MV. The radiation dose in interventional radiology study: knowledge
brings responsibility. J Vasc Interv Radiol 2003:947e51.
A, PageAA, Pettengell C,HinchliffeRJ,Loftus IM,
3 Weerakkody RA, Walsh SR, Cousins C, Goldstone KE, Tang TY, Gaunt ME.
4 Walsh SR, Cousins C, Tang TY, Gaunt ME, Boyle JR. Ionizing radiation in endo-
vascular interventions. J Endovasc Ther 2008:680e7.
5 Zhou W. Radiation exposure of vascular surgery patients beyond endovascular
procedures. J Vasc Surg 2011:39Se43S.
6 Rahimi SA, Coyle BW, Vogel TR, Haser PB, Graham AM. Acute radiation
syndrome after endovascular AAA repair. Vasc Endovascular Surg 2011:178e80.
7 Kuhelj D, Zdesar U, Jevtic V, Skrk D, Omahen G, Zontar D, et al. Risk of deter-
ministic effects during endovascular aortic stent graft implantation. Br J Radiol
8 Geijer H, Larzon T, Popek R, Beckman K- W. Radiation exposure in stent-grafting
of abdominal aortic aneurysms. Br J Radiol 2005:906e12.
9 Ho P, Cheng SWK, Wu PM, Ting ACW, Poon JTC, Cheng CKM, et al. Ionizing
radiation absorption of vascular surgeons during endovascular procedures.
J Vasc Surg 2007;46(3):455e9.
10 Kalef-Ezra JA, Karavasilis S, Ziogas D, Dristiliaris D, Michalis LK, Matsagas M.
Radiation burden of patients undergoing endovascular abdominal aortic
aneurysm repair. J Vasc Surg 2009:283e7 [discussion 87].
11 Maurel B, Sobocinski J, Perini P, Guillou M, Midulla M, Azzaoui R, et al. Evalu-
ation of radiation during EVAR performed on a mobile C-arm. Eur J Vasc
Endovasc Surg 2012:16e21.
12 Weiss DJ, Pipinos II, Longo GM, Lynch TG, Rutar FJ, Johanning JM. Direct and
indirect measurement of patient radiation exposure during endovascular aortic
aneurysm repair. Ann Vasc Surg 2008:723e9.
13 Blaszak MA, Majewska N, Juszkat R, Majewski W. Dose-area product to patients
during stent-graft treatment of thoracic and abdominal aortic aneurysms.
Health Phys 2009:206e11.
14 Majewska N, Stanisic MG, Blaszak MA, Juszkat R, Frankiewicz M, Krasinski Z,
et al. Clinical factors increasing radiation doses to patients undergoing long-
lasting procedures: abdominal stent-graft implantation. Med Sci Monit
15 Kim KP, Miller DL. Minimising radiation exposure to physicians performing
fluoroscopically guided cardiac catheterisation procedures: a review. Radiat
Prot Dosim 2009:227e33.
16 Ketteler ER, Brown KR. Radiation exposure in endovascular procedures. J Vasc
17 Bannazadeh M, Altinel O, Kashyap VS, Sun Z, Clair D, Sarac TP. Patterns of
procedure-specific radiation exposure in the endovascular era: impetus for
further innovation. J Vasc Surg 2009;49(6):1520e4.
18 Valentin J. Avoidance of radiation injuries from medical interventional proce-
dures. Ann ICRP 2000:7e67.
19 The Ionising Radiation (Medical Exposure) Regulations 2000: Satutory Instruments
2000 No 1059. London: HMSO, http://www.legislation.gov.uk/uksi/2000/1059/
G. Peach et al. / European Journal of Vascular and Endovascular Surgery 44 (2012) 395e398