Image quality optimization and radiation dose minimization in bone X-ray radiography

Abstract

In this study, the goal was to optimize image quality and minimize radiation dose in bone X-ray radiography procedure. Investigations were conducted to determine optimum quality images of the dedicated phantoms and samples at minimized radiation dose. In this regard, the main problem of this study was to find X-ray scanning parameters (voltage, current, exposure time, focal-sample distance (FSD) and X-ray filters) that give the high quality images with minimal radiation dose. The first investigation involved the establishment of the relationship of each X-ray scanning parameter with image quality indicators and the measure radiation dose independently. This relationship was established by varying each parameter during the acquisition of images and radiation dose measurements. Micro-focus X-ray machine and identifier ultra were used for acquisition of images and radiation dose monitoring respectively. ImageJ software was used to evaluate the data sets from the acquired images of the rat samples and phantoms. These data sets were further used to calculate different image quality indicators for investigation of each X-ray parameter. A multi-objective optimization problem was realised, in a sense that a conflict between different image quality indicators and radiation dose existed. In the second investigation of this study, the weight sum technique was applied in the analysis of the variation of X-ray scanning parameters in relation to image quality indicators and radiation dose. The purpose of this technique was to convert multi-objective optimization problem between image quality indicators and radiation dose into a single-objective optimization problem of the main objectives, namely image quality objective and radiation dose objective. For each X-ray scanning parameter, the final presentation of the results was included in the figures, in which the plot of the two main objectives versus the variation of each parameter and the plot of the objectives against each other were presented. The best compromise between the two objectives was searched and found in these figures. The most optimal image quality and minimized radiation dose occurred with 0.1 mm of copper (Cu) X-ray filter with X-ray tube voltage of 100 kV, X-ray current of 100μA, X-ray exposure time of 1 sec and FSD of 65 cm.