Assessing the Role of Light Absorption in Laser Lithotripsy by Isotopic Substitution of Kidney Stone Materials.

Understanding the chemical characteristics of kidney stones and how the stone composition affects their fragmentation is key to improving clinical laser lithotripsy. During laser lithotripsy, two mechanisms may be responsible for stone fragmentation: a photothermal mechanism and/or microexplosion mechanism. Herein, we carry out an isotopic substitution of crystal H2O with D2O in calcium oxalate monohydrate and struvite stones to alter their optical properties to study the relationship between the absorption of the stones, at the wavelength of the Ho:YAG (2.12 μm) laser, and the fragmentation behavior. Changing the absorption of the stones at 2.12 μm changes the extent of fragmentation, whereas changing the absorption of the bulk medium has a negligible effect on fragmentation, leading to the conclusion that kidney stone ablation is dominated by a photothermal mechanism.