We present evidence for the factorization of the world-sheet path integrals for 2d conformal field theories on the disk into bulk and boundary contributions. This factorization is then used to reinterpret a shift in closed string backgrounds in terms of boundary deformations in background independent open string field theory. We give a proof of the factorization conjecture in the cases where the background is represented by WZW and related models.

No abstract

This paper analyzes the effect of curved closed string backgrounds on the stability of D-branes within boundary string field theory. We identify the non-local open string background that implements shifts in the closed string background and analyze the tachyonic sector off-shell. The renormalization group flow reveals some characteristic properties, which are expected for a curved background, like the absence of a stable space-filling brane.In 3-dimensions we describe tachyon condensation processes to lower-dimensional branes, including a curved 2-dimensional brane. We argue that this 2-brane is perturbatively stable. This is in agreement with the known maximally symmetric WZW-branes and provides further support to the bulk-boundary factorization approach to open-closed string correspondence.⋆

Background Main purpose was to describe procedures and identify challenges in the implementation process of adaptive and non-adaptive MR-guided radiotherapy (MRgRT), especially new risks in workflow due to the new technique. We herein report the single center experience for the implementation of (MRgRT) and present an overview on our treatment practice. Methods Descriptive statistics were used to summarize clinical and technical characteristics of treatment and patient characteristics including sites treated between April 2019 and end of March 2020 after ethical approval. A risk analysis was performed to identify risks of the online adaptive workflow. Results A summary of the processes on the MR-Linac including workflows, quality assurance and possible pitfalls is presented. 111 patients with 124 courses were treated during the first year of MR-guided radiotherapy. The most commonly treated site was the abdomen (42% of all treatment courses). 73% of the courses were daily online adapted and a high number of treatment courses (75%) were treated with stereotactic body irradiation. Only 4/382 fractions could not be treated due to a failing online adaptive quality assurance. In the risk analysis for errors, the two risks with the highest risk priority number were both in the contouring category, making it the most critical step in the workflow. Conclusion Although challenging, establishment of MRgRT as a routinely used technique at our department was successful for all sites and daily o-ART was feasible from the first day on. However, ongoing research and reports will have to inform us on the optimal indications for MRgRT because careful patient selection is necessary as it continues to be a time-consuming treatment technique with restricted availability. After risk analysis, the most critical workflow category was the contouring process, which resembles the need of experienced staff and safety check paths.

Epidemiology, history, and development of SBRT as standard of careLung cancer is among the most frequent malignancies and the leading cause of cancer-related deaths worldwide (1), with non-small cell lung cancer (NSCLC) accounting for approximately 5% of all cancer-related mortality. Around 16% of patients with NSCLC are diagnosed at early stages, which are characterized by a small primary tumor and lack of lymph node metastases (stages T1-2, N0) (2). This proportion of early stage NSCLC is expected to increase in health care systems with implementation of CT-based lung cancer screening (3,4).Early-stage (ES) NSCLC has traditionally been managed by lobectomy and systematic hilar and mediastinal lymph node dissection. An overall survival of 60-92% at 5 years (5) indicates this tumor stage as a curable disease. A significant number of patients is however medically inoperable due to their comorbidities and this proportion of inoperable or high-risk patients is growing due to an aging population (6). For this group of patients, traditional treatment options have been best supportive care, limited/extra-anatomical resection, and Review Article on Radiotherapy in Thoracic Malignancies