Rofo 2017; 189(09): 844-854
DOI: 10.1055/s-0043-108996
Quality/Quality Assurance
© Georg Thieme Verlag KG Stuttgart · New York

Quality and Dose Optimized CT Trauma Protocol – Recommendation from a University Level-I Trauma Center

Qualitäts- und dosisoptimiertes CT-Polytraumaprotokoll – Empfehlung eines universitären Level-I Traumazentrums
Johannes Kahn
1   Department of Radiology, Charité School of Medicine and University Hospital, Berlin, Germany
,
David Kaul
2   Department of Radiation Oncology, Charité School of Medicine and University Hospital, Berlin, Germany
,
Georg Böning
1   Department of Radiology, Charité School of Medicine and University Hospital, Berlin, Germany
,
Roman Rotzinger
1   Department of Radiology, Charité School of Medicine and University Hospital, Berlin, Germany
,
Patrick Freyhardt
1   Department of Radiology, Charité School of Medicine and University Hospital, Berlin, Germany
,
Philipp Schwabe
3   Department of Trauma Surgery, Charité School of Medicine and University Hospital, Berlin, Germany
,
Martin H. Maurer
4   Department of Diagnostic, Interventional and Pediatric Radiology, Inselspital Bern, Switzerland
,
Diane Miriam Renz
5   Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany
,
Florian Streitparth
1   Department of Radiology, Charité School of Medicine and University Hospital, Berlin, Germany
› Author Affiliations
Further Information

Publication History

16 May 2016

27 March 2017

Publication Date:
26 June 2017 (online)

Abstract

Purpose As a supra-regional level-I trauma center, we evaluated computed tomography (CT) acquisitions of polytraumatized patients for quality and dose optimization purposes. Adapted statistical iterative reconstruction [(AS)IR] levels, tube voltage reduction as well as a split-bolus contrast agent (CA) protocol were applied.

Materials and Methods 61 patients were split into 3 different groups that differed with respect to tube voltage (120 – 140 kVp) and level of applied ASIR reconstruction (ASIR 20 – 50 %). The CT protocol included a native acquisition of the head followed by a single contrast-enhanced acquisition of the whole body (64-MSCT). CA (350 mg/ml iodine) was administered as a split bolus injection of 100 ml (2 ml/s), 20 ml NaCl (1 ml/s), 60 ml (4 ml/s), 40 ml NaCl (4 ml/s) with a scan delay of 85 s to detect injuries of both the arterial system and parenchymal organs in a single acquisition. Both the quantitative (SNR/CNR) and qualitative (5-point Likert scale) image quality was evaluated in parenchymal organs that are often injured in trauma patients. Radiation exposure was assessed.

Results The use of IR combined with a reduction of tube voltage resulted in good qualitative and quantitative image quality and a significant reduction in radiation exposure of more than 40 % (DLP 1087 vs. 647 mGyxcm). Image quality could be improved due to a dedicated protocol that included different levels of IR adapted to different slice thicknesses, kernels and the examined area for the evaluation of head, lung, body and bone injury patterns. In synopsis of our results, we recommend the implementation of a polytrauma protocol with a tube voltage of 120 kVp and the following IR levels: cCT 5mm: ASIR 20; cCT 0.625 mm: ASIR 40; lung 2.5 mm: ASIR 30, body 5 mm: ASIR 40; body 1.25 mm: ASIR 50; body 0.625 mm: ASIR 0.

Conclusion A dedicated adaptation of the CT trauma protocol (level of reduction of tube voltage and of IR) according to the examined body region (head, lung, body, bone) combined with a split bolus CA injection protocol allows for a high-quality CT examination and a relevant reduction of radiation exposure in the examination of polytraumatized patients

Key Points

  • Dedicated adaption of the CT trauma protocol allows for an optimized examination.

  • Different levels of iterative reconstruction, tube voltage and the CA injection protocol are crucial.

  • A reduction of radiation exposure of more than 40 % with good image quality is possible.

Citation Format

  • Kahn J, Kaul D, Böning G et al. Quality and Dose Optimized CT Trauma Protocol – Recommendation from a University Level-I Trauma Center. Fortschr Röntgenstr 2017; 189: 844 – 854

Zusammenfassung

Hintergrund Als überregionales Level-I Traumazentrum evaluierten wir zu Qualitäts- und Dosisoptimierungszwecken die Computertomographien (CT) polytraumatisierter Patienten. Angewandt wurden dabei iterative Rekonstruktionen sowie Röhrenspannungsreduktion verbunden mit einer Splitbolus-Kontrastmittel-Applikation.

Methoden 61 Patienten wurden in 3 verschiedenen Gruppen untersucht, die sich in der genutzten Röhrenspannung (120 – 140 kVp) und der ASIR Rekonstruktionsstufe (ASIR 20 – 50 %) unterschieden. Das Protokoll beinhaltete einen nativen kranialen und Kontrastmittel (KM) gestützten Ganzkörper-Scan (64-MSCT). Die KM-Gabe (350 mg/ml Iod) erfolgte als Splitbolus 100 ml (2 ml/s), 20 ml NaCl (1 ml/s), 60 ml (4 ml/s), 40 ml NaCl (4 ml/s), scan delay 85 s, um sowohl Verletzungen des arteriellen Gefäßsystems sowie von parenchymatösen Organen in einem Scan darstellen zu können. Die Bildqualität wurde quantitativ (SNR/CNR) und qualitativ (5-Punkte Likert Skala) in häufig von Verletzungen betroffenen Organen evaluiert. Die Strahlendosis wurde ebenfalls untersucht.

Ergebnisse Die Anwendung iterativer Rekonstruktionen zusammen mit einer Verringerung der Röhrenspannung führte zu einer gleichbleibend guten qualitativen und quantitativen Bildqualität sowie zu einer signifikanten Dosisreduktion von mehr als 40 % (DLP 1087 vs. 647 mGyxcm). Durch verschiedene Bildrekonstruktions-Stufen in Abhängigkeit der unterschiedlichen Schichtdicken, des Kernels und des Untersuchungsareals (Kopf, Lunge, Körperstamm, Knochen) konnte die Bildqualität gesteigert und alle Verletzungsmuster zuverlässig beurteilt werden. In Zusammenschau unserer Ergebnisse empfehlen wir die Durchführung eines Polytrauma-Protokolls mit einer Röhrenspannung von 120 kVp und folgenden Iterationsstufen: cCT 5mm: ASIR 20; cCT 0,625 mm: ASIR 40; Lunge 2,5 mm: ASIR 30, Körperstamm 5 mm: ASIR 40; Körperstamm 1,25 mm: ASIR 50; Körperstamm 0,625 mm: ASIR 0.

Schlussfolgerung Die dedizierte Anpassung des CT Protokolls (Grad der Spannungsreduktion und der iterativen Bildrekonstruktionsstufen) an das jeweilige Untersuchungsgebiet (Kopf, Lunge, Körperstamm, Knochen) zusammen mit einem Split-Bolus KM Injektionsprotokoll erlaubt eine gleichbleibend gute Bildqualität bei relevanter Dosisreduktion in der Untersuchung polytraumatisierter Patienten.

Kernaussagen

  • Die dedizierte Anpassung des CT Polytraumaprotokolls erlaubt eine optmierte CT Untersuchung.

  • Entscheidend sind verschiedene Level der iterativen Rekonstruktion, die Röhrenspannung sowie das KM-Protokoll.

  • Es kann eine Dosisreduktion von mehr als 40 % bei guter Bildqualität erreicht werden.

 
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