Internal medicine

Nuclear medicine

Cancer

Medical physics

Prostate

Medicine

Radiotherapy and Oncology

3rd ESTRO Forum 2015 S81Only few structures for some specific metrics, such as Dmean rectum and D98% parotid glands exhibited deviations larger than 3%.g-analysis (2%, 1mm) on the three planes at isocenter showed a pass-rate higher than 98% for all cases.Clinical evaluation in ten patients showed very good agreement with the dose calculation on the CT as expressed by the D2%, D98% and Dmean of the delineated structures.Several drawbacks were also found: the limited FOV of the kV-CBCT, which impairs the dose evaluation of those structures in its vicinity and the difference in beam profile of the kV-CBCT with respect to the CT, reducing the accuracy of the dose estimation at nearby the surface of the patient.Conclusions: The generation of three kV-CBCT specific HU-RED curves for the pelvis, thorax and H&N cases resulted in accurate dose calculation on kV-CBCT images.Very good agreement was found with the CT-based dose calculated plans according to DVH dose parameters and g-evaluation.Limitations of the kV-CBCT warrant some caution when evaluating dose differences for adaptive radiotherapy.

OC-0165: FSD measurements are obsolete when treating prostate IMRT and VMAT