Noise-robust breathing-phase estimation on marker-free, ultra low dose X-ray projections for real-time tumor localization via surrogate structures.

Purpose: This paper presents a novel strategy for feature-based breathing-phase estimation on ultra low-dose X-ray projections for tumor motion control in radiation therapy.

Methods: Coarse-scaled Curvelet coefficients are identified as motion sensitive but noise-robust features for this purpose. For feature-based breathing-phase estimation, an ensemble strategy with two classifiers is used.

Conditional random fields for phase-based lung feature tracking with ultra-low-dose x-rays.

Purpose: During radiation therapy, a continuous internal tumor monitoring without additional imaging dose is desirable. In this study, a sequential feature-based position estimation with ultra-low-dose (ULD) kV x rays using linear-chain conditional random fields (CRFs) is performed.

Methods: Four-dimensional computed tomography (4D-CTs) of eight patients serve as a-priori information from which ULD projections are simulated using a Monte Carlo method.

Feasibility of using single photon counting X-ray for lung tumor position estimation based on 4D-CT.

Purpose: In stereotactic body radiation therapy of lung tumors, reliable position estimation of the tumor is necessary in order to minimize normal tissue complication rate. While kV X-ray imaging is frequently used, continuous application during radiotherapy sessions is often not possible due to concerns about the additional dose. Thus, ultra low-dose (ULD) kV X-ray imaging based on a single photon counting detector is suggested.

Selection of Foxp3+ regulatory T cells specific for self antigen expressed and presented by Aire+ medullary thymic epithelial cells.

The parameters specifying whether autoreactive CD4(+) thymocytes are deleted (recessive tolerance) or differentiate into regulatory T cells (dominant tolerance) remain unresolved. Dendritic cells directly delete thymocytes, partly through cross-presentation of peripheral antigens 'promiscuously' expressed in medullary thymic epithelial cells (mTECs) positive for the autoimmune regulator Aire. It is unclear if and how mTECs themselves act as antigen-presenting cells during tolerance induction.

Gene repression by Pax5 in B cells is essential for blood cell homeostasis and is reversed in plasma cells.

The transcription factor Pax5 represses lineage-inappropriate genes and activates B cell-specific genes in B lymphocytes. By identifying 110 Pax5-repressed genes, we now demonstrate that Pax5 downregulates diverse biological activities including receptor signaling, cell adhesion, migration, transcriptional control, and cellular metabolism at B cell commitment. The T lymphoid or myeloid expression of these genes demonstrates that Pax5(-/-) pro-B cells and common lymphoid progenitors display lymphoid and myeloid promiscuity of gene expression.