Comparison of average Water Equivalent Diameter values between CTContour and vendor specific calculations in CT dosimetry.

Abstract

Introduction The use of size specific dose estimate, and thus its precursor water equivalent diameter, is becoming more common place in CT dosimetry. Consequently, there's an increasing interest in verifying the reliability and performance of different methods and software packages, including both open source and vendor-specific solutions, that promise to automate these calculations. This study was conducted to compare the average Water Equivalent Diameter (WED) values derived from CTContour, an open-source program for SSDE and WED calculation, with the vendor-specific values offered by Philips scanners. Method A random sample of 50 adult and 50 paediatric CT abdomenpelvis images from Philips scanners were analysed. We estimated WED values using CTContour and extracted Philips derived values from the DICOM headers. The agreement and reliability between the two methods were then evaluated using a Bland-Altman analysis. Results The average WED values obtained from CTContour were found to be slightly lower than those obtained from the vendorspecific calculations, with mean disagreements of -5.62% and -2.88% for the adult and paediatric datasets, respectively. Both methods provided clinically acceptable estimations of WED. There was no statistically significant correlation between body habitus and the level of disagreement between methods. Conclusion This study establishes that CTContour can offer WED measurements comparable to vendor-specific calculations. The discrepancies between the methods are likely the result of inherent differences in the automated WED estimation methods they employ. Future research should explore additional CT protocols beyond just abdomen-pelvis studies.