Su-Gg-J-70: Development Of An Image-Guided Conformal Small Animal Irradiation Platform

Purpose: To develop an image‐guided conformal small animal irradiation system for pre‐clinical studies. The initial dosimetric and imaging properties of the system have been characterized. Method and Materials: The system consists of a 225 kVp x‐ray tube (GE Isovolt, maximum power 3 kW, focal spot=0.4mm–3.0mm), and 20.5×20.5 cm amorphous silicon flat panel detector (512×512 pixels, 7 frames‐per‐second) mounted on a rotating gantry. The system can rotate 360°, at a maximum speed of 3 RPM. The source‐isocenter distance is 31 cm, and the source‐imager distance is 62 cm. Cone‐beam CTimages are generated from projections over half or full rotation, and reconstructed using filtered‐back projection. A motorized stage allows translational movement of specimen. Initial dosimetric characterization of the system has been done using EBT Gafchromic film in a solid water phantom at 2 cm depth. The unit is free standing and self‐shielded. Results: The maximum dose rate achievable at isocenter is 4.5 Gy/min for 220 kVp unfiltered beam, and 2 Gy/min for 220 kVp beam with 0.5mm added Cu filtration (HVL = 1.0mm Cu). The maximum dose rate for 100 kVp is 2.5 Gy/min (unfiltered) and 1.5 Gy/min with 2mm added Al filtration (HVL = 3.1 mm Al). Cone‐beam CTimages are generated with a resolution of 0.2×0.2×0.2 mm. Conclusion:Image‐guided conformal pre‐clinical irradiation systems will enable novel translational research in radiation oncology and radiobiology. The presented system has been demonstrated to provide the dose rate, mechanical stability and image‐guidance capabilities necessary to facilitate such research.