Accelerated large volume irradiation with dynamic Jaw/Dynamic Couch Helical Tomotherapy

BACKGROUND: Helical Tomotherapy (HT) has unique capacities for the radiotherapy of large and complicated target volumes. Next generation Dynamic Jaw/Dynamic Couch HT delivery promises faster treatments and reduced exposure of organs at risk due to a reduced dose penumbra. METHODS: Three challenging clinical situations were chosen for comparison between Regular HT delivery with a field width of 2.5 cm (Reg 2.5) and 5.0 cm (Reg 5.0) and DJDC delivery with a maximum field width of 5.0 cm (DJDC 5.0): Hemithoracic Irradiation, Whole Abdominal Irradiation (WAI) and Total Marrow Irradiation (TMI). For each setting, five CT data sets were chosen, and target coverage, conformity, integral dose, dose exposure of organs at risk (OAR) and treatment time were calculated. RESULTS: Both Reg 5.0 and DJDC 5.0 achieved a substantial reduction in treatment time while maintaining similar dose coverage. Treatment time could be reduced from 10:57 min to 3:42 min / 5:10 min (Reg 5.0 / DJDC 5.0) for Hemithoracic Irradiation, from 18:03 min to 8:02 min / 8:03 min for WAI and to 18:25 min / 18:03 min for TMI. In Hemithoracic Irradiation, OAR exposure was identical in all modalities. For WAI, Reg 2.5 resulted in lower exposure of liver and bone. DJDC plans showed a small but significant increase of ∼ 1 Gy to the kidneys, the parotid glans and the thyroid gland. While Reg 5.0 and DJDC were identical in terms of OAR exposure, integral dose was substantially lower with DJDC, caused by a smaller dose penumbra. CONCLUSIONS: Although not clinically available yet, next generation DJDC HT technique is efficient in improving the treatment time while maintaining comparable plan quality

Constraints-driven automatic geospatial service composition: workflows for the analysis of sea-level rise impacts

Building applications based on the reuse of existing components or services has noticeably increased in the geospatial application domain, but researchers still face a variety of technical challenges designing workflows for their specific objectives and preferences. Hence, means for automatic service composition that provide semantics-based assistance in the workflow design process have become a frequent demand especially of end users who are not IT experts. This paper presents a method for automatic composition of workflows for analyzing the impacts of sea-level rise based on semantic domain modeling. The domain modeling comprises the design of adequate services, the definition of ontologies to provide domain-specific vocabulary for referring to types and services, and the input/output annotation of the services using the terms defined in the ontologies. We use the PROPHETS plugin of the jABC workflow framework to show how users can benefit from such a domain model when they apply its constraintsdriven synthesis methods to obtain the workflows that match their intentions