Radiation dose reduction in plain radiography of the full-length lower extremity and full spine.

OBJECTIVE: To compare the diagnostic performance of standard- and low-dose radiographs of the full-length lower extremity and spine.

METHODS: This study included 223 patients who visited our hospital and received full-length lower extremity standing radiographs and full-spine radiographs. We determined the dose area product (DAP) of each image, and effective doses (ED, mSv) were calculated based on the DAP. Subjective evaluation of the full-length radiographs was based on image quality, which was assessed by bony cortex and trabecula evaluation, and on diagnostic performance, which was assessed by leg length measurement. Subjective evaluation of the full-spine radiographs was based on image quality, which was assessed by viewing the vertebral endplate, pedicle and lateral border of vertebral body, and on diagnostic performance from measurement of Cobb's angle.

RESULTS: For the full-length view and the full-spine view both the mean DAP and ED values of the standard-dose group were significantly higher than those of the low-dose group (p < 0.05). Mean scores for subjective values did not significantly differ based on the radiation dosage (p-values, 0.15-0.99). The subjective value scores for the full-length view were 2.94-2.98 in the standard-dose group and 2.91-3.00 in the low-dose group. Of note, both groups had very high scores. Additionally, the diagnostic performance scores between the two groups were also very high (range from 2.92 to 3.00).

CONCLUSION: Reducing mAs by 50% of the standard dose does not affect the radiograph image quality or its clinical validity. Advances in knowledge: Radiation dose reduction (50% of the standard dose of mAs) in plain radiography of the full-length lower extremity and full spine do not affect the clinical validity and the image quality.