54 research outputs found
Superconductivity in Undoped BaFe2As2 by Tetrahedral Geometry Design
Fe-based superconductors exhibit a diverse interplay between charge, orbital,
and magnetic ordering1-4. Variations in atomic geometry affect electron hopping
between Fe atoms5,6 and the Fermi surface topology, influencing magnetic
frustration and the pairing mechanism through changes of orbital overlap and
occupancies7-11. Here, we experimentally demonstrate a systematic approach to
realize superconductivity without chemical doping in BaFe2As2, employing
geometric design within an epitaxial heterostructure. We control both
tetragonality and orthorhombicity in BaFe2As2 through superlattice engineering,
which we experimentally find to induce superconductivity when the As-Fe-As bond
angle approaches that in a regular tetrahedron. This approach of superlattice
design could lead to insights into low dimensional superconductivity in
Fe-based superconductors
The Emerging Role of Local Therapy in Metastatic Prostate Cancer.
PURPOSE OF REVIEW:This review summarizes the prospective clinical evidence regarding local therapy in metastatic prostate cancer. RECENT FINDINGS:The phase 3 STAMPEDE trial showed that prostate radiotherapy confers a survival benefit for newly diagnosed patients with low volume metastatic hormone-sensitive prostate cancer (HSPC). No survival benefit was noted for those with high volume disease. A subsequent meta-analysis combining the data of the STAMPEDE trial with that of the HORRAD trial corroborated these findings. The phase 2 randomized STOMP trial investigated local treatment of metastases in patients with oligometastatic HSPC, and showed an improvement in hormone therapy-free survival. Local prostate radiotherapy should be offered to patients with newly diagnosed low volume metastatic HSPC. Early clinical evidence suggests that local treatment to metastatic disease might be beneficial for patients with oligometastatic HSPC, but larger trials are awaited
Dosimetric comparison of automatically propagated prostate contours with manually drawn contours in MRI-guided radiotherapy: A step towards a contouring free workflow?
Background: The prostate demonstrates inter- and intra- fractional changes and thus adaptive radiotherapy would be required to ensure optimal coverage. Daily adaptive radiotherapy for MRI-guided radiotherapy can be both time and resource intensive when structure delineation is completed manually. Contours can be auto-generated on the MR-Linac via a deformable image registration (DIR) based mapping process from the reference image. This study evaluates the performance of automatically generated target structure contours against manually delineated contours by radiation oncologists for prostate radiotherapy on the Elekta Unity MR-Linac. Methods: Plans were generated from prostate contours propagated by DIR and rigid image registration (RIR) for forty fractions from ten patients. A two-dose level SIB (simultaneous integrated boost) IMRT plan is used to treat localised prostate cancer; 6000Â cGy to the prostate and 4860Â cGy to the seminal vesicles. The dose coverage of the PTV 6000 and PTV 4860 created from the manually drawn target structures was evaluated with each plan. If the dose objectives were met, the plan was considered successful in covering the gold standard (clinician-delineated) volume. Results: The mandatory PTV 6000 dose objective (D98% > 5580Â cGy) was met in 81Â % of DIR plans and 45Â % of RIR plans. The SV were mapped by DIR only and for all the plans, the PTV 4860 dose objective met the optimal target (D98% > 4617Â cGy). The plans created by RIR led to under-coverage of the clinician-delineated prostate, predominantly at the apex or the bladder-prostate interface. Conclusion: Plans created from DIR propagation of prostate contours outperform those created from RIR propagation. In approximately 1 in 5 DIR plans, dosimetric coverage of the gold standard PTV was not clinically acceptable. Thus, at our institution, we use a combination of DIR propagation of contours alongside manual editing of contours where deemed necessary for online treatments
Predicting survival in melanoma patients treated with concurrent targeted- or immunotherapy and stereotactic radiotherapy Melanoma brain metastases prognostic score.
Background Melanoma patients frequently develop brain metastases. The most widely used score to predict survival is the molGPA based on a mixed treatment of stereotactic radiotherapy (SRT) and whole brain radiotherapy (WBRT). In addition, systemic therapy was not considered. We therefore aimed to evaluate the performance of the molGPA score in patients homogeneously treated with SRT and concurrent targeted therapy or immunotherapy (TT/IT). Methods This retrospective analysis is based on an international multicenter database (TOaSTT) of melanoma patients treated with TT/IT and concurrent (<= 30 days) SRT for brain metastases between May 2011 and May 2018. Overall survival (OS) was studied using Kaplan-Meier survival curves and log-rank testing. Uni- and multivariate analysis was performed to analyze prognostic factors for OS. Results One hundred ten patients were analyzed. 61, 31 and 8% were treated with IT, TT and with a simultaneous combination, respectively. A median of two brain metastases were treated per patient. After a median follow-up of 8 months, median OS was 8.4 months (0-40 months). The molGPA score was not associated with OS. Instead, cumulative brain metastases volume, timing of metastases (syn- vs. metachronous) and systemic therapy with concurrent IT vs. TT influenced OS significantly. Based on these parameters, the VTS score (volume-timing-systemic therapy) was established that stratified patients into three groups with a median OS of 5.1, 18.9 and 34.5 months, respectively (p = 0.001 and 0.03). Conclusion The molGPA score was not useful for this cohort of melanoma patients undergoing local therapy for brain metastases taking into account systemic TT/IT. For these patients, we propose a prognostic VTS score, which needs to be validated prospectively
Correction to: Predicting survival in melanoma patients treated with concurrent targeted- or immunotherapy and stereotactic radiotherapy: Melanoma brain metastases prognostic score (Radiation Oncology, (2020), 15, 1, (135), 10.1186/s13014-020-01558-8).
An amendment to this paper has been published and can be accessed via the original article
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