the empirical formulae for calculating mass stopping powers		Substances
$y = A_{1} e^{x / t_{1}} + y_{\circ}$
PSTAR	This work
A₁ = 5.60379 × 10⁸ t₁ = −0.03805, yₒ = 1.2486 R² = 0.99998	A₁ = 7.13118 × 10⁸ t₁ = −0.03752, yₒ = 0.31402 R² = 0.99998	Water
A₁ = 5.2736 × 10⁸, t₁ = −0.03784, yₒ = 1.08913 R² = 0.99998	A₁ = 6.760 × 10⁸ t₁ = −0.03729, yₒ = 0.17554 R² = 0.99999	Muscle, Skeletal
A₁ = 2.99461 × 10⁸, t₁ = −0.03638, yₒ = 0.71424 R² = 1	A₁ = 3.12078 × 10⁸ t₁ = −0.03626, yₒ = −0.34842 R² = 1	Bone, Cortical