Purpose: The aim of this study was to evaluate the mouse doses irradiated with our irradiation system as a function of the collimator design, including the dimensions of the collimator.
Methods: A MC mouse phantom from a tumour-bearing mouse micro-CT image set was generated. A BEAMnrc Monte-Carlo model was built of our irradiation system to model MC mouse phantom irradiation. Dose delivered to the mouse phantom was calculated, and dose volume histograms (DVHs) were generated for the tumour and organs at risk (OARs). To investigate the effect of the collimators' dimensions on the MC mouse phantom, the thickness, radius, and height of the collimator were modified in MC modeling of the collimator, and the DVHs were reanalyzed.
Results: DVHs analysis results indicate that the dose was effectively delivered to the tumour while the dose to other critical organs was minimized. Variation of the collimator height did not exhibit any significant effect on tumour’s DVHs. However, as the thickness and the radius of the collimator increased out of the collimated field dose decreased and DVHs of the OARs improved.
Conclusion: This method provides a quantitative method for characterizing the irradiation systems with no imaging capability for small animal radiotherapy.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by Queensland University of Technology grant (Institute of Health and Biomedical Innovation (IHBI) John Williams Cancer Research Scholar).