Preclinical dose assessment of cyberknife with small animal intracranial irradiation using a 3D printed mouse phantom

Dose verification in preclinical CyberKnife-based stereotactic radiosurgery (CK-SRS) of intracranial tumors is complicated by the unique characteristics of the system, including its highly conformal, non-coplanar radiation delivery and small-field irradiation. This raises concerns about the reliability of dosimetric measurements in CK-SRS radiobiological studies, emphasizing the need for standardized dosimetry protocols to improve dose accuracy and reproducibility. This study aims to evaluate a fully 3D-printed mouse phantom as a tool for preclinical intracranial CK-SRS dose verification. A 3D-printed mouse phantom was fabricated using clear resin and glass-filled polyamide (PA3200 GF) for tissue-bone-equivalent structures and modified to accommodate both EBT3 film and thermoluminescent dosimeters (TLD). Two treatment configurations were employed using CyberKnife M6 system, including two simple static field plans and two complex non-planar plans. The dosimetric evaluation of the mouse phantom involved comparing the mean dose and dose discrepancies between film profile measurements, TLD-derived point-dose readings, and the corresponding doses calculated by the treatment plan system (TPS) for each configuration. Across all measurements for single-beam and non-planer stereotactic treatment configuration, dose values exhibited a deviation of no more than 4.20% from the corresponding TPS calculated data. The 2D dose distributions obtained from the film measurements and those calculated by the TPS were successfully registered. The mean dose differences for lateral profiles showed a high level of agreement, with discrepancies of only 2.23%. Similarly, the agreement was similarly excellent with a mean dose difference of 2.31% along the anteroposterior axes. TLD measurements also displayed comparable agreement with TPS-calculated results, with the maximum dose difference recorded at 2.20% for the single-beam and 4.12% for the non-planar treatment configuration. This study demonstrates the utility of 3D-printed mouse phantom for accurate dose assessment in preclinical intracranial CK-SRS. The phantom serves as an effective tool for pre-treatment dose verification, improving dosimetric precision while offering a cost-efficient solution for radiobiological research.