The expression P(x)=-0.0008x2+0.0193x+96.9999 could accurately describe the mathematical relationship between BPF and age in normal subject (lower limit of 95% CI y=-0.0008x2+0.0184x+95.1090).

• BPF定量与年龄之间的二次多项式函数关系P(x)=-0.；0008x2+0