Fig. 4.

a: The reduced Chi-square ( ${\chi }_{\nu }^2$) versus 1st reduced velocity at 1.8, 2.4, and 3 J cm⁻² and (b) 2nd reduced velocity at 5.4, 6, and 6.6 J cm⁻² for the case of a lesion treated at 60 mW cm⁻². For the 1st blood velocity reduction (a), the goodness-of-fit is sensitive to fluence, but for the 2nd decrease (b), the goodness-of-fit is more sensitive to the choice of the value of the reduced velocity. The width E (μm second⁻¹) is a measure of the uncertainty in the best fit reduced blood flow velocity and is defined as half the distance in velocity between the minimum in ${\chi }_{\nu }^2$ and the nearest, symmetrically positioned sampled velocities.