Effects of AEC chamber selection on patient dose and image quality during direct digital PA chest radiography.

Abstract

Introduction Postero-anterior (PA) chest x-ray (CXR) examinations are the most commonly performed Radiographic examinations. Generally, x-ray examinations of the chest include the use of automatic exposure control (AEC). When using AEC the radiographer must select the correct chamber configuration by determining which ion-chambers are the most appropriate for a particular radiographic examination. An evident variation exists among imaging departments, regarding the choice of the AEC chambers for a PA CXR examination. Purpose of the study The main purpose of this research was to perform a comparative study at a local public general hospital to identify which AEC chamber configuration contributes to the lowest radiation dose without compromising image quality for the PA CXR examination. Materials and methods A quantitative, prospective approach was selected for this experimental, comparative study. The research study was divided into two main parts: a phantom study and a clinical study. The currently used AEC chamber configuration at the local general public hospital (both lateral chambers) was set as the control. Following the phantom study, the two AEC configurations that contributed to the lowest radiation dose were: the right lateral and the left lateral chamber configurations. These two AEC chamber configurations were compared with the current configuration in a clinical study comprising of both male and female subjects (n=60), in order to evaluate the extent to which optimisation of radiation doses was achievable in the clinical setting. Finally, the effects on image quality was subjectively evaluated by radiologists and radiographers (n=S) in a visual grading analysis (VGA). Results Based on the clinical study results, there was no statistically significant difference (p<::O.OS) in the radiation dose for the PA CXR examination between the both lateral and the right or left lateral AEC chamber configurations. However, the right lateral chamber was linked with the lowest mean radiation dose in both males and females. Moreover, this research demonstrates considerable differences in the mean radiation dose (p\< 0.05) between the left and right lateral AEC chamber configurations in males. The results of this study also indicate that whichever of the three AEC configurations is used, image quality is not compromised. Conclusions On the basis of the research findings, radiographers can optimise the radiation dose during a PA CXR examination by selecting the right lateral AEC chamber configuration for a PA CXR. However, it is highly recommended that further research is conducted on a wider range of radiographic equipment/devices.