Publications by authors named "Grehn M"

: Accurate target definition, treatment planning and delivery increases local tumor control for radiotherapy by minimizing collateral damage. To achieve this goal for uveal melanoma (UM), tantalum fiducial markers (TFMs) were previously introduced in proton and photon beam radiotherapy. However, TFMs cause pronounced scattering effects in imaging that make the delineation of small tumors difficult.

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Background/purpose: High doses to healthy cardiac substructures (CS) in stereotactic arrhythmia radioablation (STAR) raise concerns regarding potential treatment-induced cardio-toxicity. However, CS contours are not routinely created, hindering the understanding of the CS dose-effect relationships. To address this issue, the alignment of CS contouring was initiated within the STOPSTORM consortium.

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Article Synopsis
  • - The study focuses on Stereotactic Arrhythmia Radioablation (STAR) as a treatment for ventricular tachycardia (VT), especially when traditional catheter-based methods are not viable, emphasizing the challenges in accurately defining treatment targets based on electro-anatomic maps (EAM).
  • - Two different software solutions were evaluated for their effectiveness in transferring 2D target data from EAM into 3D CT volume coordinates, with a cross-validation study conducted on data from ten patients.
  • - Results showed that the target volumes and surface areas obtained from both methods were nearly identical, suggesting that both software solutions are reliable for ensuring quality assurance and enhancing treatment accuracy in STAR procedures.
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Purpose: STereotactic Arrhythmia Radioablation (STAR) showed promising results in patients with refractory ventricular tachycardia. However, clinical data are scarce and heterogeneous. The STOPSTORM.

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Stereotactic arrhythmia radioablation (STAR) is a noninvasive treatment of refractory ventricular tachycardia (VT). In this study, we aimed to systematically review prospective trials on STAR and pool harmonized outcome measures in a meta-analysis. After registration in the International Prospective Register of Systematic Reviews (PROSPERO: CRD42023439666), we searched OVID Medline, OVID Embase, Web of Science Core Collection, the Cochrane Central Register of Controlled Trials, and Google Scholar on November 9, 2023, to identify reports describing results of prospective trials evaluating STAR for VT.

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Background And Purpose: In patients with recurrent ventricular tachycardia (VT), STereotactic Arrhythmia Radioablation (STAR) shows promising results. The STOPSTORM.eu consortium was established to investigate and harmonise STAR treatment in Europe.

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Article Synopsis
  • Stereotactic arrhythmia radioablation (STAR) is a treatment for patients with hard-to-treat ventricular tachycardia (VT), but its impact on implantable cardioverter defibrillator (ICD) functioning was unknown.
  • A study examined ICD performance before and after STAR in 43 patients, focusing on adverse events and lead parameters (sensing, capture threshold, impedance).
  • Results showed no significant ICD issues post-treatment, with only one minor event and overall safe operation of STAR concerning ICD function.
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Aim: To identify the optimal STereotactic Arrhythmia Radioablation (STAR) strategy for individual patients, cardiorespiratory motion of the target volume in combination with different treatment methodologies needs to be evaluated. However, an authoritative overview of the amount of cardiorespiratory motion in ventricular tachycardia (VT) patients is missing.

Methods: In this STOPSTORM consortium study, we performed a literature review to gain insight into cardiorespiratory motion of target volumes for STAR.

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Background: Single-session cardiac stereotactic radiation therapy (SBRT) has demonstrated promising results for patients with refractory ventricular tachycardia (VT). However, the full safety profile of this novel treatment remains unknown and very limited data from prospective clinical multicenter trials are available.

Methods: The prospective multicenter multiplatform RAVENTA (radiosurgery for ventricular tachycardia) study assesses high-precision image-guided cardiac SBRT with 25 Gy delivered to the VT substrate determined by high-definition endocardial and/or epicardial electrophysiological mapping in patients with refractory VT ineligible for catheter ablation and an implanted cardioverter defibrillator (ICD).

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The EU Horizon 2020 Framework-funded Standardized Treatment and Outcome Platform for Stereotactic Therapy Of Re-entrant tachycardia by a Multidisciplinary (STOPSTORM) consortium has been established as a large research network for investigating STereotactic Arrhythmia Radioablation (STAR) for ventricular tachycardia (VT). The aim is to provide a pooled treatment database to evaluate patterns of practice and outcomes of STAR and finally to harmonize STAR within Europe. The consortium comprises 31 clinical and research institutions.

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A novel quality assurance process for electroanatomical mapping (EAM)-to-radiotherapy planning imaging (RTPI) target transport was assessed within the multi-center multi-platform framework of the RAdiosurgery for VENtricular TAchycardia (RAVENTA) trial. A stand-alone software (CARDIO-RT) was developed to enable platform independent registration of EAM and RTPI of the left ventricle (LV), based on pre-generated radiotherapy contours (RTC). LV-RTC were automatically segmented into the American-Heart-Association 17-segment-model and a manual 3D-3D method based on EAM 3D-geometry data and a semi-automated 2D-3D method based on EAM screenshot projections were developed.

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Purpose: Cardiac radioablation is a novel treatment option for patients with refractory ventricular tachycardia unsuitable for catheter ablation. The quality of treatment planning depends on dose specifications, platform capabilities, and experience of the treating staff. To harmonize the treatment planning, benchmarking of this process is necessary for multicenter clinical studies such as the RAdiosurgery for VENtricular TAchycardia trial.

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Background/aim: Many patients with head-and-neck cancers receive radiotherapy. Treatment planning can be very complex in case of dental fillings or implants that cause metal artefacts. Verification of dose distributions may be performed using specific phantoms.

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Structural relaxation phenomena in binary and multicomponent lithium silicate glasses were studied upon irradiation with femtosecond (fs) laser pulses (800 nm central wavelength, 130 fs pulse duration) and subsequent thermal annealing experiments. Depending on the annealing temperature, micro-Raman spectroscopy analyses evidenced different relaxation behaviours, associated to bridging and non-bridging oxygen structures present in the glass network. The results indicate that the mobility of lithium ions is an important factor during the glass modification with fs-laser pulses.

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Purpose: Although the metric precision of robotic stereotactic body radiation therapy in the presence of breathing motion is widely known, we investigated the dosimetric implications of breathing phase-related residual tracking errors.

Methods And Materials: In 24 patients (28 liver metastases) treated with the CyberKnife, we recorded the residual correlation, prediction, and rotational tracking errors from 90 fractions and binned them into 10 breathing phases. The average breathing phase errors were used to shift and rotate the clinical tumor volume (CTV) and planning target volume (PTV) for each phase to calculate a pseudo 4-dimensional error dose distribution for comparison with the original planned dose distribution.

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The cyanobacterium Acaryochloris marina is unique because it mainly contains Chlorophyll d (Chl d) in the core complexes of PS I and PS II instead of the usually dominant Chl a. Furthermore, its light harvesting system has a structure also different from other cyanobacteria. It has both, a membrane-internal chlorophyll containing antenna and a membrane-external phycobiliprotein (PBP) complex.

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Article Synopsis
  • The study examined how demographic and socioeconomic factors impact infection rates in adolescents in Switzerland over a 3-year period.
  • Among 196 adolescents aged 15-16, a 9.7% infection rate was found, with a significant disparity where 30% of foreign nationals tested positive compared to 7.3% of native adolescents.
  • The low overall infection rate among Swiss adolescents suggests a high standard of living, which seems to lessen the impact of socioeconomic factors on infection prevalence.
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Coagulase-negative staphylococci (CoNS), particularly Staphylococcus epidermidis, are increasingly being recognized as opportunistic pathogens. They are often multiply antibiotic resistant and can cause nosocomial outbreaks. For clinical and epidemiological reasons, accurate species identification and typing are imperative.

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Recurrent contamination of bacteriological specimens with Candida parapsilosis led to epidemiological investigations which indicated persistent colonization of carbon dioxide incubators as the most likely source. Changes in the technical arrangements and institution of a meticulous cleansing protocol eliminated contamination of specimens but not colonization of the incubators. Tests for tolerance of 17% NaCl and survival at 50 degrees C, and SDS-PAGE analysis of crude cell extracts allowed discrimination between epidemic and non-epidemic isolates, while enzyme profile analysis and susceptibility studies failed as typing methods.

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Fifteen out of 24 risk neonates from the premature baby ward (= 63%) and 36 of 79 healthy neonates from the infant nursery (= 46%) at a Zürich hospital were infected within a period of 29 days during a nosocomial epidemic human rotavirus (HRV) outbreak. Forty-two out of 51 of all HRV-infected babies (=82%) manifested clinical symptoms, but these could not all be attributed to an HRV infection. On average, rotavirus could be detected in infected risk neonates five days after their admission to the premature baby ward.

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During a nine-month period in 1986, we observed five ornithine decarboxylase-negative isolates of Serratia marcescens from four different patients. All isolates were identical in more than 50 biochemical parameters. Four isolates from three hospitalized patients were essentially identical in their susceptibility patterns to 12 antimicrobial agents.

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