With reference to Ultrasonography, the correct order of the materials/tissues with ascending values for the half value layer is:
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Remember: High Attenuation = Small HVL and Low Attenuation = Large HVL. Bone stops ultrasound instantly (tiny HVL), while water lets it glide through with minimal loss (huge HVL).
$\text{Bone (Smallest HVL)} \longrightarrow \text{Fat} \longrightarrow \text{Water (Largest HVL)}$