Standardization of Occupational Dose to Patient DAP Enables Reliable Assessment of Radiation-Protection Devices in Invasive Cardiology

Abstract

Purpose: With the aim of assessing the effectiveness of radiation-protection devices in invasive cardiology, the goal of this study was to validate relative parameters for operator occupational exposure, standardized to the patient's primary dose. Material and Methods: One of these parameters was the local dose, measured in air at the operator's position per dose area product (DAP), applied to a male anthropomorphic Alderson-Rando phantom for simulation of coronary angiography. The second parameter was personal occupational dose to the operator per DAP, measured by thermoluminescence dosimeter stripes during 121 procedures in routine clinical work. Results: The local and personal doses per unit DAP - using typical 0.5-mm lead overcouch and undercouch protection - were comparable (left eye 180 vs. 360, thyroid 260 vs. 260, left shoulder 280 vs. 150, chest 400 vs. 500, hands 400 vs. 550, waist 900 vs. 400 nSv/Gy × cm²). The results, however, were far lower than typically reported values. Our findings therefore disclose a typically inadequate use or acceptance by individual operators of available table-attached lead protection devices, and of ceiling-attached lead-glass screens. The additional use of individual 1.0-mm lead-equivalent garments reduced local doses to levels between 1 ... 10 %. Conclusions: DAP-standardized dose parameters - determined experimentally (phantom measurements), or in routine clinical work - are not appreciably influenced by the equipment age and type, or by the image-intensifier entrance dose rate of the respective catheterization system. They are consequently best suited for obtaining eloquent comparisons of various radiation-protection devices, and for reliable estimation of local scatter radiation exposure by simple documentation of intervention DAP.

Zusammenfassung

Ziel: Bestimmung der Wirksamkeit von Strahlenschutzmitteln mittels Orts- bzw. Körperdosismessungen bei invasiv tätigen Kardiologen. Material und Methoden: Experimentell wurde an einem Alderson-Phantom eine Koronarangiographie simuliert und die Ortsdosis am Aufenthaltsort des kardiologischen Untersuchers in Abhängigkeit des applizierten Dosis-Flächen-Produktes (DFP) gemessen. Verglichen wurden diese Ergebnisse mit kumulativen Untersucher-Körperdosen, normiert auf das kumulative DFP im Verlauf von 121 koronaren Prozeduren. Ergebnisse: Unter Verwendung einer 0,5-mm bleiäquivalenten Über- und Untertischstreustrahlenabschirmung entsprach der experimentelle Quotient weitgehend den entsprechenden klinischen Messwerten: linkes Auge 180 vs. 360, Schilddrüse 260 vs. 260, linke Schulter 280 vs. 150, Brusthöhe 400 vs. 500, Hände 400 vs. 550, Bauchhöhe 900 vs. 400 nSv/Gy × cm². Beide Quotienten lagen weit unterhalb publizierter Werte: Dies weist auf einen weithin inadäquaten Gebrauch fest installierter Strahlenschutzvorrichtungen in der invasiven Kardiologie hin. Die korrekte Anwendung zusätzlicher Schutzbekleidung von 1,0-mm Blei-Äquivalenz reduzierte die Untersucher-Körperdosis auf 1 … 10 %. Schlussfolgerungen: Da die DFP-normierten Körperdosiswerte des Untersuchers kaum von Alter, Typ oder Bildverstärkereingangsdosisleistung einer Herzkatheteranlage beeinflusst werden, ermöglichen sie eine verlässliche Bewertung von Strahlenschutzvorrichtungen und im Falle vergleichbarer Untersuchungsbedingungen eine Abschätzung der Untersucher-Körperdosis aus dem applizierten DFP.

Radiation exposure - interventional radiology - radiation-protection devices - dose area product

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