A comparative study of internationally used constancy testing protocols for medical imaging devices

Abstract

Background: One of the difficulties confronted by medical physicists is the variability in constancy testing protocols and acceptable tolerances promoted by different international standard setting and Medical Physics professional organizations around the world. Objectives: This project compared protocols and tolerances from different organizations focussing on their similarities, differences, and relative strengths and weaknesses. Methodology: The methodology that was used in this study is a comparative qualitative documentary thematic analysis of constancy testing protocols published by the IEC, EU Commission, IAEA, IPEM, AAPM and ACR. The thematic categories and labels that were analysed were: Document Metadata (Document Number, Recency, Price of Document), Equipment used in the constancy testing (Equipment required, Expense of the Equipment, Ease of Availability), Measurement protocol for constancy testing (Professional Performing the Test, Level of Complexity), Test Frequency and Tolerance Limits. Results: The results from the data collection were presented in four comparative thematic template tables, one for each modality considered in the study (Digital Radiography, Mammography, Fluoroscopy, Computed Tomography). Conclusions and Recommendations: From this study, the main conclusion that was drawn was that there isn’t one specific organization that publishes suitable constancy testing protocols for all the selected imaging modalities and that one often needs to take good practice elements from more than one organization when setting up own protocols. Recommendations for specific imaging modalities were put forward.