C-arm angulation increases radiation exposure to the head during complex EVAR

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Operators should be aware of radiation exposure to the head increasing with angulation of the C-arm and limit this manoeuvre, according to a study presented at the ESVS Annual Meeting (23–25 September 2014, Stockholm, Sweden).

“Reliance on endovascular techniques and increasing procedural complexity means that the vascular interventionalist is exposed to significant radiation doses, particularly to unprotected body parts,” says Mostafa A Albayati, Academic Department of Vascular Surgery, Guy’s and St Thomas’ NHS Foundation Trust/King’s College London, London, UK. “We aimed to directly measure head and body radiation exposure to the operating team during complex endovascular aortic procedures.”

Between October 2013 and July 2014, consecutive elective branched and fenestrated endovascular aortic repair (EVAR) procedures performed in a hybrid operating theatre were prospectively analysed. Body (over-lead and under-lead) and head doses were measured for the primary and assistant operator using electronic dosimeters. Fluoroscopy and digital subtraction angiography (DSA) acquisition times, C-arm angulation, dose area product (DAP) and operator height were recorded. Data were analysed using Mann-Whitney U test and linear regression modelling.

Seventeen cases were analysed (Crawford II [n=4], Crawford III [n=2], Crawford IV [n=11]) with a median operative time of 280 (IQR 200–330) minutes. Median age was 76 (71–81) years; median body mass index was 28 (25–32) kg/m2; 82% were male. Stent grafts incorporated branches only (n=4), fenestrations only (n=10) or a mixture of branches and fenestrations (n=3). A total of 21 branches and 37 fenestrations were cannulated and stented.

Head dose was significantly higher in the primary operator compared with assistant operator (median 54 [24–130] μSv versus 15 [7–43] μSv, respectively; p=0.022) as was over-lead body dose (median 80 [37–163] μSv versus 32 [6–48] μSv, respectively; p=0.003). The corresponding under-lead (“total body effective”) doses were similar between operators (p=0.222). Primary operator height (r2= -0.649; p=0.042), DSA acquisition time in left anterior oblique (LAO) position (r2=0.629; p=0.026) and degree of LAO angulation (r2=0.648; p=0.019) were independent predictors of greater primary operator head dose.

Albayati commented: “The head is an unprotected area that receives a significant radiation dose during complex EVAR. The deleterious effects of exposure to this area are not fully understood. Operators should be cognisant of head exposure increasing with angulation of the C-arm and limit this manoeuvre.”

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