Increasing the x-ray film to focus distance (FFD), has been recommended as a practical dose optimization tool for patients undergoing conventional radiological procedures. In the previous study, we demonstrated a 32% reduction in absorbed dose is achievable due to increasing the FFD from 100 to 130 cm during pediatric chest radiography. The aim of this study was to examine whether increasing the FFD from 100 to 130 cm is equally effective for other common radiological procedures and performing a literature review of published studies to address the feasibility and probable limitations against implementing this optimization tool in clinical practice.
Materials and Methods
Radiographic examination of the pelvis (AP view), abdomen (AP view), skull (AP and lateral view), and spine (AP and lateral view), were taken of pediatric patients. The radiation dose and image quality of a radiological procedure is measured in FFD of 100 cm (reference FFD) and 130 cm (increased FFD). The thermo-luminescent dosimeters (TLD) were used for radiation dose measurements and visual grading analysis (VGA) for image quality assessments.
Results: Statistically significant reduction in the ESD ranged from 21.91% for the lateral skull projection to 35.24% for the lateral spine projection was obtained, when the FFD was increased from 100 to 130 cm (P<0.05). Optimum image quality was obtained for all projections in both FFDs. VGA of the resultant images demonstrated a statistically non-significant minor increase in image quality of lateral skull and spine projections, when increasing from 100 to 130 cm FFDs (P>0.05).
Increasing the FFD from 100 to 130 cm has significantly reduced radiation exposure without affecting on image quality. Our findings are commensurate with the literatures and emphasized that radiographers should learn to use of an updated reference FFD of 130 cm in clinical practice.