Dose-area-product (DAP) modelling of Siemens Max-series X-ray digital radiography (DR) systems

Abstract

PurposeTo develop a dose-area-product (DAP) model of Siemens Max-series x-ray digital radiography (DR) systems for pre-exposure DAP estimation. Methods and materialsSeries of commissioning exposures were taken with varying x-ray tube voltage (kVp), and milliampere-second (mAs) and imaging protocols (thorax PA, pelvis and knee) on a Fusion Max and Ysio Max unit respectively. Correlations of dose-area-product (DAP) values with kVp and mAs were analyzed, and a quasi-linear model were proposed as DAP(mAs, kVp) = a∙mAs∙kVp + b∙kVp, which was validated on commissioning data. Then, the DAP estimation models were verified with clinical data from four radiology centers, and relative errors between model estimates and measurements were analyzed. ResultsField size, mAs and kVp are found to be the key factors that influence DAP values, which exhibit significant linear-correlations both with kVp and mAs. The model parameters (a, b) on Fusion and Ysio units are not equal, which indicates slight difference in imaging chains. The validation results show that the proposed DAP estimation model can well depict the DAP dependence on kVp and mAs on both units. In preliminary clinical verification, relative errors between model estimates and measurements are significantly correlated to field-size deviations. ConclusionsWhile the model parameters are field-size dependent, the proposed model framework exhibits great viability on DAP estimation on both Fusion Max and Ysio Max units, and may contribute in pre-exposure imaging parameter fine-tuning on Max-series DR units.