Background: Grating-based x-ray dark-field and phase-contrast imaging allow extracting information about refraction and small-angle scatter, beyond conventional attenuation. A step towards clinical translation has recently been achieved, allowing further investigation on humans.
Methods: After the ethics committee approval, we scanned the full body of a human cadaver in anterior-posterior orientation. Six measurements were stitched together to form the whole-body image. All radiographs were taken at a three-grating large-object x-ray dark-field scanner, each lasting about 40 s. Signal intensities of different anatomical regions were assessed. The magnitude of visibility reduction caused by beam hardening instead of small-angle scatter was analysed using different phantom materials. Maximal effective dose was 0.3 mSv for the abdomen.
Results: Combined attenuation and dark-field radiography are technically possible throughout a whole human body. High signal levels were found in several bony structures, foreign materials, and the lung. Signal levels were 0.25 ± 0.13 (mean ± standard deviation) for the lungs, 0.08 ± 0.06 for the bones, 0.023 ± 0.019 for soft tissue, and 0.30 ± 0.02 for an antibiotic bead chain. We found that phantom materials, which do not produce small-angle scatter, can generate a strong visibility reduction signal.
Conclusion: We acquired a whole-body x-ray dark-field radiograph of a human body in few minutes with an effective dose in a clinical acceptable range. Our findings suggest that the observed visibility reduction in the bone and metal is dominated by beam hardening and that the true dark-field signal in the lung is therefore much higher than that of the bone.
Keywords: Dark-field imaging; Human body; Radiography; Whole-body imaging; X-rays.
源光栅 (G0) 的面积为 5.0 ×2.5 cm2，周期为 68.72 μm，占空比为 0.7；
其他两个光栅（G1：周期 8.73 μm，占空比0.5，G2：周期 10 μm，占空比 0.5）由八块拼接而成，每块尺寸为 5.0 × 2.5 cm2，以实现每个光栅的总尺寸为 40 × 2.5 cm2。 G0-G1 和G1-G2 距离分别为 1.60 和 0.25 m。 全部光栅是金填充衰减光栅（金填充150–200 μm 的高度）。