Laser Beam Shaping for Surgery and Microbiopsy
Abstract
Lasers are increasingly being used for surgery in a wide range of medical specialties due to their advantages over alternative
surgical tools. Advantages include precise material removal, limited bleeding, and delivery through optical fibers enabling use
in body cavities and for minimally invasive surgeries. Advancements in laser technology including new laser wavelengths and
higher power continue to improve the performance and implementation of surgical lasers. Temporal beam shaping, or pulse
modulation, has been implemented into clinical laser systems to increase efficiency of urological surgeries, leading to faster,
safer procedures. However, the precise mechanisms of temporally shaped laser ablation are not fully understood. The effects
of spatial beam shaping on laser tissue ablation have not previously been explored.
We aim to understand the impact of temporal and spatial laser beam on laser ablation to improve the performance and
increase the applications of laser surgery. Working towards this aim, a Ho:YAG laser was temporally and spatially altered and
the effects on tissue ablation were explored. We explored the mechanisms of pulse modulated ablation through experiments
on phantoms and native kidney stones. We discovered that increased ablation efficiency by pulse modulation is composition
dependent. Next, increased ablation efficiency by altering laser spatial shape was explored. We discovered that shaping the
laser beam into an annular shape led to an increase in ablation efficiency in both hard and soft tissues. Finally, we explored
the application of spatially shaped laser ablation for laser microbiopsy to harvest sub-microliter (<1 mm3) tissue samples.
Laser beam shaping, pulse energy, and application of cryogen spray cooling were optimized to successfully harvest tissue
sections with observable histological features. Harvested tissues were imaged with confocal microscopy and “virtual H&E”
methods were used to digitally color the images to mimic H&E stained tissue sections. Laser microbiopsy with virtual H&E is
minimally invasive, precise, and provides images in a fraction of the time of the traditional pathology workflow.
Biography
Dr. Jason King recently graduated with his PhD in biomedical engineering from the University of Texas at Austin. His work
focuses on optimization of laser ablation for surgery and biopsy through temporal and spatial laser beam shaping. This work
includes computational modeling and ablation experiments aimed at understanding light tissue interactions involved in laser
ablation. His other research interests include confocal microscopy and Raman spectroscopy for cancer diagnosis and
monitoring.
