The Use of EPID-based in vivo Dosimetry for Small Animal Radiation Research

OBJECTIVE To validate the feasibility of electronic portal imaging device (EPID)-based in vivo dosimetry system for the verification of small animal radiation researchMETHODS The workflow can be divided into three steps. In the first part, external body of the rat phantom was modeled based on the computed tomography (CT) dataset of a real rat previously scanned for another radiobiological experiment and the structure set was exported to 3D Slicer program to convert DICOM file to. stl file format. Tissue-equivalent rat phantom was, then, printed using Makerbot Replicator Z18 3D-printer. In the second part, treatment plans were created for different anatomical sites including whole brain and total lung irradiation using Elekta Versa HD linear accelerator. In the last part, measurements were performed with EPID-based 3D in vivo dosimetry system. During the analysis, 3D gamma analysis method was used and gamma evaluation criteria were set to 3 mm distance-to-agreement and 3% dose differences for local dose.RESULTS According to our analysis, EPID measurement for each modality and anatomical site met the protocol value except for % gamma <= 1 and gamma mean values for total lung irradiation, but both of these parameters met the proposed minor variation criteria.CONCLUSION Implementation of EPID-based 3D in vivo dosimetry for preclinical radiation research with small animals seems to be feasible.