Development of a radiopaque tiltmeter to improve reproducibility for Fowler's position on chest radiography

INTRODUCTION

We have developed a novel radiopaque tiltmeter (ROT) that can indicate patient tilt during a radiography examination and display it on X-ray images. This study evaluated the effect of variation of patient tilt on the reproducibility of Fowler's position for chest radiography and the accuracy of the ROT.

METHODS

We evaluated the reproducibility of Fowler's position based on changes from the first day in the central venous catheter (CVC) tip position and the cardiothoracic ratio (CTR) with and without a digital tiltmeter to verify its efficacy in patients who underwent mobile chest radiography. The ROT contains radiopaque liquid consisting of white barium sulfate solution and oil and has a scale bar of 15°-75° with increments of 15° to indicate ROT tilt. The ROT tilt was increased from 10° to 80° in increments of 10°. We then evaluated (1) the difference between the ROT tilt and the tilt measured with a digital tiltmeter, and (2) the ROT tilt displayed on the X-ray image.

RESULTS

With regard to reproducibility in Fowler's position, changes in the CVC tip position were 2.8 ± 3.9 mm and 10.7 ± 10.6 mm with and without the tiltmeter, respectively (p < 0.05) and the respective rates of change in the CTR were 0.7% ± 0.6% and 4.0% ± 2.1% (p < 0.05). Differences between the ROT tilt and the tilt measured by the digital tiltmeter were within ±2.5°. All ROT tilts displayed on the X-ray images were recognized exactly as each tilt.

CONCLUSION

Our novel ROT had the potential to accurately indicate patient tilt during chest radiography, which could be helpful in terms of reproducibility and precise follow-up.

IMPLICATIONS FOR PRACTICE

Use of the ROT for determination of patient tilt can improve reproducibility in Fowler's position, allowing more accurate serial X-ray imaging.