Water-sensitive photoacoustic temperature characterization at 960 nm in cerebral vascular phantoms with CT...

Precise temperature monitoring is important for thermal therapy, vascular physiology, and brain function research. Photoacoustic thermometry often relies on hemoglobin-related wavelengths and is easily affected by hemoglobin concentration, oxygenation, and optical fluence. Here, we propose and validate a water-sensitive photoacoustic thermometry strategy at 960 nm in cerebrovascular phantom configurations containing a straight human whole-blood channel, with and without a bone-like shell. CT-guided registration enabled structurally constrained ROI analysis. Although frame-by-frame PAI signals fluctuated, clear temperature-dependent trends were preserved and strengthened by statistical aggregation. In the phantom without the bone-like shell, 0.1°C temperature-binned median aggregation yielded an apparent calibration R² of 0.996 and a temperature inversion RMSE of 0.08°C; after 100-frame averaging, the noise-equivalent temperature difference decreased to 0.124°C. For the phantom with a bone-like shell, an R² > 0.976 and an RMSE of 0.13°C were still achieved, supporting robust 960 nm photoacoustic thermometry in hemoglobin-containing cerebrovascular phantom environments.