Höhe und Röhrenangulation als die Determinanten der möglichen Untersucher-Ortsdosisleistung in der invasiven Kardiologie

Zusammenfassung

Ziel: Experimentelle Bestimmung der Ortsdosisleistung des Untersuchers in der invasiven Kardiologie in Abhängigkeit von Bodenhöhe und Röhrenangulation. Material und Methoden: An einem Alderson-Rando-Phantom zur Simulation des Patienten bestimmten wir die Durchleuchtungs-Körperdosis (µSv/h) in Untersucherposition in 20-cm-Schritten von 20 - 200 cm Körperhöhe für alle Röhrenangulationen in 30°-Schritten von rechts anterior oblique (RAO) 90° bis links anterior oblique (LAO) 90° und, sofern seitens der Gerätegeometrie realisierbar, in 10°-Schritten in den kraniokaudalen Ebenen bis 40°. Ergebnisse: Die Untersucher-Körperdosis steigt von einem Minimum zwischen postero-anteriorem (PA) 0°-Strahlengang und RAO 30° kontinuierlich auf das doppelte bzw. 5- bis 10fache Niveau in weit lateral angulierter RAO- bzw. LAO-Projektion an. Kraniokaudale 30°-Angulationen verursachen 2- bis 3fach höhere Untersucher-Körperdosisleistungen. Maximalwerte in weit angulierten kranialen (+) Projektionen wandern von 160 cm Bodenhöhe in LAO 90°/30°+ (3500) über 50 cm Bodenhöhe in PA 0°/30° + (400 µSv/h) und bei ≥ 170 (600 µSv/h) und ≤ 40 cm (300 µSv/h) Bodenhöhe in RAO 90°/30° + Projektion. Kaudale (-) Angulationen verursachen etwas geringere Körperdosen mit Maximalwerten bei 120 cm Bodenhöhe in LAO 90°/30°- (3000 µSv/h), bei 50 cm Bodenhöhe in PA 0°/30°- Projektion (300 µSv/h) und bei ≥ 170 (900 µSv/h) und ≤ 40 cm (500 µSv/h) Bodenhöhe in RAO 90°/30°- Projektion. Schlussfolgerungen: Vorliegende aussagefähige Datensammlung zur Untersucher-Streustrahlenexposition in Abhängigkeit von Röhrenangulation und Bodenhöhe ermöglicht kardiologischen Interventionalisten, ihre bevorzugten Projektionen strahlenhygienisch zu überprüfen und gegebenenfalls zu verändern.

Abstract

Purpose: To map in an experimental setting of the local personal operator dose for 55 selected tube angulations as a function of body height above ground. Materials and Methods: On an Alderson-Rando phantom representing the patient, we performed measurements of fluoroscopy scatter radiation (µSv/h) at the operator’s position, for the range of 20 - 200 cm body height, for all tube angulations in 30° steps from right anterior oblique (RAO) 90° to left anterior oblique (LAO) 90° position, and for planes angulated cranially (+) and caudally (-) by 10°, 20°, 30°, and 40°, unless rendered unfeasible by geometric circumstances. Results: Radiation exposure to the operator is lowest between postero-anterior (PA) 0° and RAO 30° angulation, and continuously increases by a factor of approx. 2 towards steep RAO, and to factors of 5 - 10 towards steep LAO views. Craniocaudal angulation at 30° likewise generates personal dose levels 2 - 3 times as high. For all body heights and all LAO tube angulations, the corridor between 0° - 10° caudal angulation generates the least personal scatter dose, likewise irrespective of body height and craniocaudal tube angulations, the corridor between 0° PA - 30° RAO angulation. RAO angulations, however, being inverse to the respective 90° LAO angulations, are generally 4 to 5 times less radiation extensive. Peak levels of the local personal dose vary from 160 cm body height for steep cranial LAO 90°/30°+ views (3,500 µSv/h), to 50 cm for cranial PA 0°/30°+ (400 µSv/h), and to ≥ 170 cm (600 µSv/h) and ≤ 40 cm (300 µSv/h) for steep cranial RAO 90°/30°+ views. Caudal angulations generate slightly lower doses, with peak levels at 120 cm for LAO 90°/30°- views (3,000 µSv/h), at 50 cm for PA 0°/30°- views (300 µSv/h), and above 170 cm (900 µSv/h) and below 40 cm (500 µSv/h) for steep caudal RAO 90°/30°- views. Conclusion: The present experimental study on scatter radiation to the operator, as a function of body height and tube angulation, offers a representative data tool for all interventionists for use in invasive cardiology, to confirm the radiation safety of their favored coronary views, or to encourage less radiation-intensive angulations. Moreover, it provides new knowledge about special risks for crucial body regions and enables effectve radiation protection strategies.

Key words

Dosimetry - radiation safety - operator’s personal dose - coronary angiography - education

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