Film retakes in digital and conventional radiography

To determine the film-retake rates and causes in digital radiography comparison to conventional X-rays method.

Comparative study.

Radiology Department, Aga Khan University Hospital, Karachi, from January 2004 to December 2006.

X-rays of different body parts, conducted during the year 2004, with conventional radiography (n=170300), and in 2006 with digital radiography (n=174550), were included in this study. Measurements were done for number of X-rays re-take due to different quality control reasons for both the conventional and digital radiography. Quality control reasons included underexposure, overexposure, positioning errors, patient movements, portable X-rays, grid cutoff, and others (i.e. equipment related) due to which X-ray quality was questionable. Results were expressed in percentages.

A total of 9423 X-rays (5.5%) were repeated in conventional radiography (n=170300) due to underexposure (38%), overexposure (28.5%), positioning errors (25%), portable procedures (4%), patient movement (2%), grid cut-off (0.5%), and others (2%). Underexposure was the most frequently responsible factor for the X-ray repetition as compared to other factors (p<0.001). In digital radiography (n=174550), 1464 X-rays (1%) needed to be repeated, which was significantly less in comparison to X-ray repetition in conventional method of radiography (5.5%) [p<0.001]. In digital radiography, the most frequent factor for X-ray re-take was positioning error (435, 30%).

Digital radiography is associated with significantly lesser number of re-take X-rays as compared to conventional radiography, hence minimizes the exposure of the patients to unnecessary radiations due to re-take X-rays. Positioning error remains a problem even in digital radiography, emphasizing training need for technologists.