A Reduction in Radiographic Exposure and Image Quality in Film Screen Postero-anterior Chest Radiography

Abstract

Purpose: To develop a protocol for the optimization of diagnostic chest radiography examination, the effect of radiographic exposure reduction on image quality is investigated.
Procedure: Fourty-eight adult patients presenting for posterior-anterior (PA) chest radiography in a tertiary health care centre were categorized into 3 groups to assess the effects of exposure (tube current/time mAs) reduction on clinical image quality using in film screen (FS) chest radiography. Images were obtained at existing departmental exposure protocol (T1) while a record of the exposure factors was made. Test exposures obtained by reducing average mAs values by 20% (T2) and 50% (T3) were used to obtain radiographic images of patients following normal ethically based clinical practice. To make up for the reduction in mAs, a 4% increase in the T1 kVp was used. The quality of images obtained with each exposure protocol was studied by two Consultant Radiologists, using the image quality criteria of the Commission of European Communities (CEC). Assessors used the method of ranked scoring and worked independently.
Results: Results showed no change in image quality following the 20% exposure (mAs) reduction. However, there was a significant change in image quality at 50% reduction of mAs values (P < 0.05) with higher image quality scores suggesting improved perceptibility of all assessed criteria among the observers.
Conclusion: Improving radiation protection of the patient while maintaining diagnostic quality of the radiographic image at reduced exposures is a clinically desirable development. This study will find application in current efforts at optimization of radiography procedures in the area of study.

Keywords: Radiography, exposure reduction, image quality, chest, quality control.