@article{chasteney94a,
  author = {E. A. Chasteney and S. A. Prahl and K. W. Gregory},
  title = {A Simple Model for Spectrophotometric Determination of Thrombus Ablation Mass},
  journal = {Laser Med. Surg.},
  year = {1994 abstract only},
  volume = {S6},
  pages = {62},
  abstract = {Despite rapid advances in thrombolysis, few methods exist for measuring thrombus removal. The total volume of lysis effluent and the optical absorbance(Abs) of this effluent provide the basis for a simple method to find the mass removed providing there is no destruction of the hemoglobin chromophore. The absorbance of a known reference dilution of lysed thrombus is used for calibration. $$ \mathrm{Mass} = {\mathrm{(sample Abs)(reference concentration)(sample volume)}\over \mathrm{(reference Abs)}} $$ This method was applied to study the wavelength dependence of pulsed-dyed laser thrombolysis for photomechanical disruption of thrombus. Porcine red blood cells (RBC) in 3.5\% gelatin were used for a reproducible ablation substrate in 5\,mm tubes. Five 2\,$\mu$s laser pulses (480 or 577\,nm) were delivered through a 1mm fluid core catheter onto the submerged gelatin target. Non-laser controls were used to correct for RBC diffusion from the gelatin. The effluent was collected, weighed, and then heated to dissolve gelatin fragments. The absorbance at 410\,nm was measured and corrected for diffusion. \begin{tabular}{lccc} & & 480nm & 577nm\\ & & (N=8) & (N=9)\\ Ablation threshold & (mJ) & 29 & 21\\ Energy & (mJ) & 106 & 101\\ Ablation mass/pulse & ($\mu$g) & 480$\pm$150 & 810$\pm$320(p=0.06) \end{tabular} \vskip2mm \textbf{Conclusion}: 1)Thrombolysis mass determination by spectrophotometry provides previously unavailable quantitative data for determining the optimal parameters for pulsed-dye laser ablation. 2)There is increased ablation at 577\,nm, where the absorption coefficient ($\mu_a$) of hemoglobin is twice that of 480\,nm. 3)This method may prove useful for studying other mechanical and pharmacologic thrombolysis techniques. 4)RBC-gelatin provides a reproducible substrate for modeling thrombus ablation.},
}