Quantifying the setup uncertainty of a stereotactic murine micro-image guided radiation therapy system

Area of Science:

• * Preclinical research
• * Radiation oncology
• * Neuroscience

Background:

• * Stereotactic stages are crucial for precise animal model positioning in preclinical research.
• * Image guidance systems enhance accuracy in radiation therapy.
• * Reproducibility is key for reliable experimental outcomes in animal studies.

Purpose of the Study:

• * To assess the reproducibility of murine cranial positioning using a stereotactic stage.
• * To quantify accuracy improvements offered by the X-RAD SmART irradiator's on-board image guidance.
• * To establish guidelines for stereotactic accuracy in preclinical irradiation experiments.

Main Methods:

• * Intermouse reproducibility was evaluated using athymic nude mice (N=60 measurements) fixed on a stereotactic stage and imaged with cone-beam CT (CBCT).
• * Intramouse reproducibility was assessed with C57BL/6 mice (N=24 measurements) over seven days, with daily CBCT localization.
• * Positional shifts were calculated to quantify setup accuracy based on stereotactic coordinates and CBCT alignment.

Main Results:

• * Mean vector shifts between stereotactic setup and CBCT alignment were 0.78 ± 0.27 mm for intermouse analysis.
• * Mean vector shifts were 0.82 ± 0.34 mm for intramouse analysis.
• * These results indicate millimeter-level accuracy achievable with stereotactic positioning alone.

Conclusions:

• * Cranial irradiation with millimeter uncertainties can rely on stereotactic coordinates from daily CBCT.
• * Submillimeter accuracy requirements necessitate daily image guidance for each mouse.
• * This study introduces an efficient method for high-throughput stereotactic experiments using the X-RAD SmART irradiator.