Statistical breathing curve sampling to quantify interplay effects of moving lung tumors in a 4D Monte Carlo dose calculation framework.

Purpose: The interplay between respiratory tumor motion and dose application by intensity modulated radiotherapy (IMRT) techniques can potentially lead to undesirable and non-intuitive deviations from the planned dose distribution. We developed a 4D Monte Carlo (MC) dose recalculation framework featuring statistical breathing curve sampling, to precisely simulate the dose distribution for moving target volumes aiming at a comprehensive assessment of interplay effects.

Methods: We implemented a dose accumulation tool that enables dose recalculations of arbitrary breathing curves including the actual breathing curve of the patient.

Single-isocenter stereotactic radiosurgery for multiple brain metastases: Impact of patient misalignments on target coverage in non-coplanar treatments.

Frameless single-isocenter non-coplanar stereotactic radiosurgery (SRS) for patients with multiple brain metastases is a treatment at high geometrical complexity. The goal of this study is to analyze the dosimetric impact of non-coplanar image guidance with stereoscopic X-ray imaging. Such an analysis is meant to provide insights on the adequacy of safety margins, and to evaluate the benefit of imaging at non-coplanar configurations.

Planning Benchmark Study for Stereotactic Body Radiation Therapy of Liver Metastases: Results of the DEGRO/DGMP Working Group on Stereotactic Radiation Therapy and Radiosurgery.

Purpose: Our purpose was to investigate whether liver stereotactic body radiation therapy treatment planning can be harmonized across different treatment planning systems, delivery techniques, and institutions by using a specific prescription method and to minimize the knowledge gap concerning intersystem and interuser differences. We provide best practice guidelines for all used techniques.

Methods And Materials: A multiparametric specification of target dose (gross target volume [GTV], GTV, GTV, planning target volume [PTV]) with a prescription dose of GTV = 3 × 20 Gy and organ-at-risk (OAR) limits were distributed with computed tomography and structure sets from 3 patients with liver metastases.

Stereotactic body radiotherapy in patients with hepatocellular carcinoma in a multimodal treatment setting.

Purpose: Retrospective evaluation of stereotactic body radiation therapy (SBRT) in patients with hepatocellular carcinoma (HCC).

Methods: We retrospectively analyzed 36 patients (45 lesions) treated between 2011 and 2017. Twenty-seven had previous treatments.

Comparison of planned dose on different CT image sets to four-dimensional Monte Carlo dose recalculation using the patient's actual breathing trace for lung stereotactic body radiation therapy.

Purpose: The need for four-dimensional (4D) treatment planning becomes indispensable when it comes to radiation therapy for moving tumors in the thoracic and abdominal regions. The primary purpose of this study is to combine the actual breathing trace during each individual treatment fraction with the Linac's log file information and Monte Carlo 4D dose calculations. We investigated this workflow on multiple computed tomography (CT) datasets in a clinical environment for stereotactic body radiation therapy (SBRT) treatment planning.

Dose variability in different lymph node levels during locoregional breast cancer irradiation: the impact of deep-inspiration breath hold.

Purpose: Aim of the present analysis was to evaluate the movement and dose variability of the different lymph node levels of node-positive breast cancer patients during adjuvant radiotherapy (RT) with regional nodal irradiation (RNI) in deep-inspiration breath hold (DIBH).

Methods: Thirty-five consecutive node-positive breast cancer patients treated from October 2016 to February 2018 receiving postoperative RT of the breast or chest wall including RNI of the supra-/infraclavicular lymph node levels (corresponding to levels IV, III, Rotter LN (interpectoral), and some parts of level II) were analyzed. To evaluate the lymph node level movement, a center of volume (COV) was obtained for each lymph node level for free-breathing (FB) and DIBH plans.

Stereotactic body radiation therapy (SBRT) in patients with hepatocellular carcinoma and oligometastatic liver disease.

Background: To report our experience with SBRT in primary and secondary liver tumors.

Methods: We retrospectively analysed 55 patients (70 lesions) with a median follow-up of 10 months (range 1-57) treated from 2011 to 2016. All patients had not been eligible for other local treatment options.

Clinical workflow optimization to improve 4DCT reconstruction for Toshiba Aquilion CT scanners.

Respiratory motion remains a source of major uncertainties in radiotherapy. Respiratory correlated computed tomography (referred to as 4DCT) serves as one way of reducing breathing artifacts in 3D-CTs and allows the investigation of tumor motion over time. The quality of the 4DCT images depends on the data acquisition scheme, which in turn is dependent on the vendor.

Planning benchmark study for SBRT of early stage NSCLC : Results of the DEGRO Working Group Stereotactic Radiotherapy.

Purpose: The aim was to evaluate stereotactic body radiation therapy (SBRT) treatment planning variability for early stage nonsmall cell lung cancer (NSCLC) with respect to the published guidelines of the Stereotactic Radiotherapy Working Group of the German Society for Radiation Oncology (DEGRO).

Materials And Methods: Planning computed tomography (CT) scan and the structure sets (planning target volume, PTV; organs at risk, OARs) of 3 patients with early stage NSCLC were sent to 22 radiotherapy departments with SBRT experience: each department was asked to prepare a treatment plan according to the DEGRO guidelines. The prescription dose was 3 fractions of 15 Gy to the 65% isodose.

Stereoscopic X-ray imaging, cone beam CT, and couch positioning in stereotactic radiotherapy of intracranial tumors: preliminary results from a cross-modality pilot installation.

Background: To assess the accuracy and precision of a fully integrated pilot installation of stereoscopic X-ray imaging and kV-CBCT for automatic couch positioning in stereotactic radiotherapy of intracranial tumors. Positioning errors as detected by stereoscopic X-ray imaging are compared to those by kV-CBCT (i.e.

Feasibility study on image guided patient positioning for stereotactic body radiation therapy of liver malignancies guided by liver motion.

Background: Fiducial markers are the superior method to compensate for interfractional motion in liver SBRT. However this method is invasive and thereby limits its application range. In this retrospective study, the compensation method for the interfractional motion using fiducial markers (gold standard) was compared to a new non-invasive approach, which does rely on the organ motion of the liver and the relative tumor position within this volume.

Technical evaluation of different respiratory monitoring systems used for 4D CT acquisition under free breathing.

Respiratory monitoring systems are required to supply CT scanners with information on the patient's breathing during the acquisition of a respiration-correlated computer tomography (RCCT), also referred to as 4D CT. The information a respiratory monitoring system has to provide to the CT scanner depends on the specific scanner. The purpose of this study is to compare two different respiratory monitoring systems (Anzai Respiratory Gating System; C-RAD Sentinel) with respect to their applicability in combination with an Aquilion Large Bore CT scanner from Toshiba.

Characteristics of gated treatment using an optical surface imaging and gating system on an Elekta linac.

Background: Knowing the technical characteristics of gated radiotherapy equipment is crucial for ensuring precise and accurate treatment when using techniques such as Deep-Inspiration Breath-Hold and gating under free breathing. With one of the first installations of the novel surface imaging system Catalyst™ (C-RAD AB, Sweden) in connection with an Elekta Synergy linear accelerator (Elekta AB, Sweden) via the Elekta Response Interface, characteristics like dose delivery accuracy and time delay were investigated prior to clinical implementation of gated treatments in our institution.

Methods: In this study a moving phantom was used to simulate respiratory motion which was registered by the Catalyst™ system.

Identification and characterization of a novel porin family highlights a major difference in the outer membrane of chlamydial symbionts and pathogens.

The Chlamydiae constitute an evolutionary well separated group of intracellular bacteria comprising important pathogens of humans as well as symbionts of protozoa. The amoeba symbiont Protochlamydia amoebophila lacks a homologue of the most abundant outer membrane protein of the Chlamydiaceae, the major outer membrane protein MOMP, highlighting a major difference between environmental chlamydiae and their pathogenic counterparts. We recently identified a novel family of putative porins encoded in the genome of P.

Proteomic analysis reveals a virtually complete set of proteins for translation and energy generation in elementary bodies of the amoeba symbiont Protochlamydia amoebophila.

Chlamydiae belong to the most successful intracellular bacterial pathogens. They display a complex developmental cycle and an extremely broad host spectrum ranging from vertebrates to protozoa. The family Chlamydiaceae comprises exclusively well-known pathogens of humans and animals, whereas the members of its sister group, the Parachlamydiaceae, naturally occur as symbionts of free-living amoebae.

Proteomic analysis of the outer membrane of Protochlamydia amoebophila elementary bodies.

Chlamydiae are obligate intracellular bacteria, comprising some of the most important bacterial pathogens of animals and humans. During their unique developmental cycle they have to attach to and enter their eukaryotic host cells, a process mediated by proteins in the chlamydial outer membrane. So far the only experimental data for chlamydial outer membrane proteins are available from members of the Chlamydiaceae, a family comprising exclusively human and animal pathogens.

Rv1698 of Mycobacterium tuberculosis represents a new class of channel-forming outer membrane proteins.

Mycobacteria contain an outer membrane composed of mycolic acids and a large variety of other lipids. Its protective function is an essential virulence factor of Mycobacterium tuberculosis. Only OmpA, which has numerous homologs in Gram-negative bacteria, is known to form channels in the outer membrane of M.

Characterization of nanostructured surfaces generated by reconstitution of the porin MspA from Mycobacterium smegmatis.

Nanostructures with long-term stability at the surface of gold electrodes are generated by reconstituting the porin MspA from Mycobacterium smegmatis into a specially designed monolayer of long-chain lipid surfactant on gold. Tailored surface coverage of gold electrodes with long-chain surfactants is achieved by electrochemically assisted deposition of organic thiosulfates (Bunte salts). The subsequent reconstitution of the octameric-pore MspA is guided by its extraordinary self-assembling properties.

High-level expression of the mycobacterial porin MspA in Escherichia coli and purification of the recombinant protein.

MspA is the prototype of a new family of tetrameric porins and provides the main general diffusion pathway for hydrophilic compounds through the outer membrane of Mycobacterium smegmatis. Structural analysis was hampered by the scarce amount of pure protein. After replacement of the GC-rich codons of the mspA gene by codons optimal for high-level expression in Escherichia coli, the mature MspA protein was overproduced in E.

The core of the tetrameric mycobacterial porin MspA is an extremely stable beta-sheet domain.

MspA is the major porin of Mycobacterium smegmatis mediating the exchange of hydrophilic solutes across the cell wall and is the prototype of a new family of tetrameric porins with a single central pore of 10 nm in length. Infrared and circular dichroism spectroscopy revealed that MspA consists mainly of antiparallel beta-strands organized in a coherent domain. Heating to 92 and 112 degrees C was required to dissociate the MspA tetramer and to unfold the beta-sheet domain in the monomer, respectively.

A tetrameric porin limits the cell wall permeability of Mycobacterium smegmatis.

Mycobacteria protect themselves with an outer lipid bilayer, which is the thickest biological membrane hitherto known and has an exceptionally low permeability rendering mycobacteria intrinsically resistant against many antibiotics. Pore proteins mediate the diffusion of hydrophilic nutrients across this membrane. Electron microscopy revealed that the outer membrane of Mycobacterium smegmatis contained about 1000 protein pores per microm(2), which are about 50-fold fewer pores per microm(2) than in Gram-negative bacteria.