3rd ESTRO Forum 2015 S441 Energy plans were normalized such that 95% of the PTV received the prescription dose. Once prescription was achieved, the doses to OARs, such as spinal cord, heart, esophagus, and healthy lungs were iteratively lowered until standard deviation of the dose across the PTV in each plan became less than 4%. Dose indices (DIs), such as D PTV 95% (dose to 95% of the PTV), D Cord 1% , D esophagus 50% , D heart 33% , D lungs 20% , D lungs 30% , and volume indices (VIs) such as

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... V lungs 2000 cGy , and V lungs 3000 cGy were compared. The dosimetric differences among the DIs and the VIs were subjected to a two-tailed paired ttest to determine the statistically significant dose differences (p < 0.05). Results: The table below summarizes statistically significant differences over all indices. Negative differences indicate lower doses/masses/integral doses with Energy optimization. On average the DIs and the VIs resulting from the Energy optimization are lower than the indices obtained with Dvh optimization. With very few exceptions this is true for each individual DI and VI. Notably, the total energy deposited in the entire volume outside of the target was on average lower for Energy optimization with statistically significant difference of 14.4%. The same was true for each patient, i.e. the integral dose outside of the PTV was always lower with energy optimization. Conclusions: It was found that in inverse planning Energy based optimization results in lower doses to nearby OARs. For identical target coverage Energy based plans resulted in statistically significant OAR sparing ranging from 18% to more than 80%. Purpose/Objective: The aim of VoxTox is to establish delivered dose over a course of radiotherapy and its relationship with toxicity, in 1920 participants treated with Intensity Modulated IGRT for head and neck cancer, prostate cancer, or a central nervous system tumour. As part of the VoxTox project, we required a system for automatic recalculation of dose cubes, using the MV CT images acquired for IGRT on a TomoTherapy machine. Materials and Methods: We have developed a system that can be integrated within the GANGA computational-task management system originally developed for use on the