Air bubble artefact: A new type of artifact on CT heads

Abstract

Introduction An artefact was observed on CT head scans which was inconsistent in occurrence and mimicked pathologies. It was not initially identified on quality control checks and phantom studies. It was confirmed by the manufacturer to be due to the presence of air bubbles in the tube oil cooling system. Purpose A review of the sequence of events was undertaken to assess the clinical impact of the artefact and identify action to be taken locally and by the manufacturer to prevent a recurrence. Materials and methods Routine quality control tests were performed and reviewed by the Lead Radiographer and Medical Physics Expert. The artefact was investigated further with the CTDI Perspex head phantom scanned using the clinical acquisition protocol. The artefact was not originally identified on these images. The site contacted the manufacturer who were able to remotely identify the cause of the artefact. Results Images relating to the investigation were reviewed following information from the manufacturer. The artefact was found to be present on routine quality control images and on CTDI Perspex head phantom images when viewed at a narrow window width of 40. All images passed the quantitative tests based. Clinical scans were reviewed by the radiologists to assess the clinical impact and identify inappropriate clinical events. Conclusion The air bubble artefact mimicked pathologies and could result in inappropriate clinical events. Routine quality control tests were not adequate to detect the artefact. These have been modified to address this in future.