Room: Karl Dean Ballroom B1
Purpose: Laser interstitial thermal therapy, or LITT, is a minimally invasive stereotactic tumor ablative technique. One application is treating intracranial targets. LITT systems use a laser energy probe that can be inserted into the patient, emitting near infrared laser radiation that induces necrosis in clinical targets while providing thermal damage updates via MR thermometry. The rigid laser probes range two and three mm in diameter, through which the thermal energy efficiently emits along straight-line pathways. The systems allow for varying dwell times and rates of energy deposition to assist in the ability to maximize the thermal damage to the target tissues while minimizing the damage to normal tissues. For targets that cannot be treated along a linear trajectory, multiple trajectories are necessary. However, planning systems, like those available in ionizing radiation delivery, are all but absent from the clinical setting. The goals of this project aim to provide a planning system to allow the optimization of the laser trajectory.
Methods: Twelve patients who underwent LITT therapy using traditional approaches, where the surgeon decided on laser trajectory by inspection of orthogonal radiology images were post procedure planned using a rudimentary system of LITT planning. Starting with a stereotactic planning system, a thermal dose kernel was developed. This effort has provided a rudimentary tool that yields first estimates for optimized LITT.
Results: A conformal index was developed and evaluated for each planning technique. The average index for the simple inspection of orthogonal images based on thermal dose threshold lines was 88.4% while the conformal index of the planning system were 46.2%.
Conclusion: As with ionizing radiation, it is anticipated that this increase in thermal optimization will translate into better tumor control and lower complications. A system, with a more precise thermal predictive algorithm and automated trajectory planning is being pursued.
Funding Support, Disclosures, and Conflict of Interest: I am under Non-Disclosure Agreement with Monteris Medical, Inc. We are provided technical support without funding by Monteris Medical, Inc.
Treatment Planning, MRI, Lasers
TH- Non-ionizing radiation therapies : thermal therapy- planning, dosimetry, monitoring