1. Evaluation of two-dimensional dose distributions for pre-treatment patient-specific IMRT dosimetryĐeni Smilović Radojčić, David Rajlić, Božidar Casar, Manda Švabić Kolacio, Nevena Obajdin, Dario Faj, Slaven Jurković, 2018, original scientific article Abstract: The accuracy of dose calculation is crucial for success of the radiotherapy treatment. One of the methods that represent the current standard for patient-specific dosimetry is the evaluation of dose distributions measured with an ionization chamber array inside a homogeneous phantom using gamma method. Nevertheless, this method does not replicate the realistic conditions present when a patient is undergoing therapy. Therefore, to more accurately evaluate the treatment planning system (TPS) capabilities, gamma passing rates were examined for beams of different complexity passing through inhomogeneous phantoms. Materials and methods The research was performed using Siemens Oncor Expression linear accelerator, Siemens Somatom Open CT simulator and Elekta Monaco TPS. A 2D detector array was used to evaluate dose distribution accuracy in homogeneous, semi-anthropomorphic and anthropomorphic phantoms. Validation was based on gamma analysis with 3%/3mm and 2%/2mm criteria, respectively. Results Passing rates of the complex dose distributions degrade depending on the thickness of non-water equivalent material. They also depend on dose reporting mode used. It is observed that the passing rate decreases with plan complexity. Comparison of the data for all set-ups of semi-anthropomorphic and anthropomorphic phantoms shows that passing rates are higher in the anthropomorphic phantom. Conclusions Presented results raise a question of possible limits of dose distribution verification in assessment of plan delivery quality. Consequently, good results obtained using standard patient specific dosimetry methodology do not guarantee the accuracy of delivered dose distribution in real clinical cases
Keywords: IMRT, 2D dose verification, gamma method, antropomorphic phantom
Published in DiRROS: 10.06.2024; Views: 56; Downloads: 35
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2. Quantitative insights on impurities in ice cores at the micro-scale from calibrated LA-ICP-MS imagingPascal Bohleber, Piers Larkman, Nicolas Stoll, David Clases, Raquel Gonzalez de Vega, Martin Šala, Marco Roman, Carlo Barbante, 2024, original scientific article Published in DiRROS: 10.06.2024; Views: 52; Downloads: 28
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3. Dynamic susceptibility contrast enhanced (DSC) MRI perfusion and plasma cytokine levels in patients after tonic-clonic seizuresTatjana Filipovič, Katarina Šurlan Popović, Alojz Ihan, David B. Vodušek, 2017, original scientific article Abstract: Background Inflammatory events in brain parenchyma and glial tissue are involved in epileptogenesis. Blood concentration of cytokines is shown to be elevated after tonic-clonic seizures. As a result of inflammation, blood-brain barrier leakage occurs. This can be documented by imaging techniques, such is dynamic susceptibility contrast enhanced (DSC) MRI perfusion. Our aim was to check for postictal brain inflammation by studying DSC MRI perfusion and plasma level of cytokines. We looked for correlations between number and type of introducing seizures, postictal plasma level of cytokines and parameters of DSC MRI perfusion. Furthermore, we looked for correlation of those parameters and course of the disease over one year follow up. Patients and methods We prospectively enrolled 30 patients, 8%24 hours after single or repeated tonic-clonic seizures. Results 25 of them had normal perfusion parameters, while 5 had hyperperfusion. Patients with hyperperfusion were tested again, 3 months later. Two of 5 had hyperperfusion also on control measurements. Number of index seizures negatively correlated with concentration of proinflammatory cytokines IL-10, IFN-[gamma] and TNF-[alpha] in a whole cohort. In patients with hyperperfusion, there were significantly lower concentrations of antiinflammatory cytokine IL-4 and higher concentrations of proinflammatory TNF-[alpha]. Conclusions Long lasting blood- brain barrier disruption may be crucial for epileptogenesis in selected patients.
Keywords: cytokines, blood-brain barrier, tonic-clonic seizures
Published in DiRROS: 03.06.2024; Views: 105; Downloads: 73
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4. Unearthing the soil-borne microbiome of land plantsRaúl Ochoa-Hueso, David J. Eldridge, Miguel Berdugo, Pankaj Trivedi, Blessing Sokoya, Concha Cano-Díaz, Sebastian Abades, Fernando D. Alfaro, Adebola R. Bamigboye, Felipe Bastida, Tine Grebenc, Tina Unuk Nahberger, 2024, original scientific article Abstract: Plant–soil biodiversity interactions are fundamental for the functioning of terrestrial ecosystems. Yet, the existence of a set of globally distributed topsoil microbial and small invertebrate organisms consistently associated with land plants (i.e., their consistent soil-borne microbiome), together with the environmental preferences and functional capabilities of these organisms, remains unknown. We conducted a standardized field survey under 150 species of land plants, including 58 species of bryophytes and 92 of vascular plants, across 124 locations from all continents. We found that, despite the immense biodiversity of soil organisms, the land plants evaluated only shared a small fraction (less than 1%) of all microbial and invertebrate taxa that were present across contrasting climatic and soil conditions and vegetation types. These consistent taxa were dominated by generalist decomposers and phagotrophs and their presence was positively correlated with the abundance of functional genes linked to mineralization. Finally, we showed that crossing environmental thresholds in aridity (aridity index of 0.65, i.e., the transition from mesic to dry ecosystems), soil pH (5.5; i.e., the transition from acidic to strongly acidic soils), and carbon (less than 2%, the lower limit of fertile soils) can result in drastic disruptions in the associations between land plants and soil organisms, with potential implications for the delivery of soil ecosystem processes under ongoing global environmental change.
Keywords: belowground networks, environmental thresholds, moss microbiome, plant microbiome, plant–soil interactions
Published in DiRROS: 31.05.2024; Views: 72; Downloads: 72
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5. Mechanism of action, potency and efficacy : considerations for cell therapiesCarl G. Simon Jr., Erich H. Bozenhardt, Christina M. Celluzzi, David Dobnik, Melanie L. Grant, Uma Lakshmipathy, Thiana Nebel, 2024, original scientific article Abstract: One of the most challenging aspects of developing advanced cell therapy products (CTPs) is defining the mechanism of action (MOA), potency and efficacy of the product. This perspective examines these concepts and presents helpful ways to think about them through the lens of metrology. A logical framework for thinking about MOA, potency and efficacy is presented that is consistent with the existing regulatory guidelines, but also accommodates what has been learned from the 27 US FDA-approved CTPs. Available information regarding MOA, potency and efficacy for the 27 FDA-approved CTPs is reviewed to provide background and perspective. Potency process and efficacy process charts are introduced to clarify and illustrate the relationships between six key concepts: MOA, potency, potency test, efficacy, efficacy endpoint and efficacy endpoint test. Careful consideration of the meaning of these terms makes it easier to discuss the challenges of correlating potency test results with clinical outcomes and to understand how the relationships between the concepts can be misunderstood during development and clinical trials. Examples of how a product can be “potent but not efficacious” or “not potent but efficacious” are presented. Two example applications of the framework compare how MOA is assessed in cell cultures, animal models and human clinical trials and reveals the challenge of establishing MOA in humans. Lastly, important considerations for the development of potency tests for a CTP are discussed. These perspectives can help product developers set appropriate expectations for understanding a product’s MOA and potency, avoid unrealistic assumptions and improve communication among team members during the development of CTPs.
Keywords: cell therapy product, efficacy endpoint test, mechanism of action, potency test, metrology
Published in DiRROS: 27.05.2024; Views: 100; Downloads: 99
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6. Connectivity with uncertainty regions given as line segmentsSergio Cabello, David Gajser, 2024, original scientific article Abstract: For a set ${\mathcal Q}$ of points in the plane and a real number $\delta \ge 0$, let $\mathbb{G}_\delta({\mathcal Q})$ be the graph defined on ${\mathcal Q}$ by connecting each pair of points at distance at most $\delta$. We consider the connectivity of $\mathbb{G}_\delta({\mathcal Q})$ in the best scenario when the location of a few of the points is uncertain, but we know for each uncertain point a line segment that contains it. More precisely, we consider the following optimization problem: given a set ${\mathcal P}$ of $n-k$ points in the plane and a set ${\mathcal S}$ of $k$ line segments in the plane, find the minimum $\delta \ge 0$ with the property that we can select one point $p_s\in s$ for each segment $s\in {\mathcal S}$ and the corresponding graph $\mathbb{G}_\delta( {\mathcal P}\cup \{ p_s\mid s\in {\mathcal S}\})$ is connected. It is known that the problem is NP-hard. We provide an algorithm to exactly compute an optimal solution in ${\mathcal O}(f(k) n \log n)$ time, for a computable function $f(\cdot)$. This implies that the problem is FPT when parameterized by $k$. The best previous algorithm uses ${\mathcal O}((k!)^k k^{k+1}\cdot n^{2k})$ time and computes the solution up to fixed precision.
Keywords: computational geometry, uncertainty, geometric optimization, fixed parameter tractability, parametric search
Published in DiRROS: 13.05.2024; Views: 131; Downloads: 135
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7. A statistical model describing combined irreversible electroporation and electroporation-induced blood-brain barrier disruptionShirley Sharabi, Bor Kos, David Last, David Guez, Dianne Daniels, Sagi Harnof, Yael Mardor, Damijan Miklavčič, 2016, original scientific article Keywords: electroporation, blood brain barrier, Peleg-Fermi
Published in DiRROS: 09.05.2024; Views: 164; Downloads: 106
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8. Schwarz-Pick lemma for harmonic maps which are conformal at a pointFranc Forstnerič, David Kalaj, 2024, original scientific article Abstract: We obtain a sharp estimate on the norm of the differential of a harmonic map from the unit disc ${\mathbb D}$ in ${\mathbb C}$ into the unit ball ${\mathbb B}^n$ in ${\mathbb R}^n$, $n\ge 2$, at any point where the map is conformal. In dimension $n=2$, this generalizes the classical Schwarz-Pick lemma, and for $n\ge 3$ it gives the optimal Schwarz-Pick lemma for conformal minimal discs ${\mathbb D}\to {\mathbb B}^n$. This implies that conformal harmonic immersions $M \to {\mathbb B}^n$ from any hyperbolic conformal surface are distance-decreasing in the Poincaré metric on $M$ and the Cayley-Klein metric on the ball ${\mathbb B}^n$, and the extremal maps are precisely the conformal embeddings of the disc ${\mathbb D}$ onto affine discs in ${\mathbb B}^n$. Motivated by these results, we introduce an intrinsic pseudometric on any Riemannian manifold of dimension at least three by using conformal minimal discs, and we lay foundations of the corresponding hyperbolicity theory.
Keywords: harmonic maps, minimal surfaces, Schwarz–Pick lemma, Cayley–Klein metric
Published in DiRROS: 25.04.2024; Views: 227; Downloads: 87
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10. Indeksiranje in citiranje strokovne literatureDavid Ožura, 2024, independent scientific component part or a chapter in a monograph Keywords: onkologija, klinične raziskave, citatni indeksi, kvantitativno vrednotenje raziskovalne uspešnosti, dejavnik vpliva revije, odprta znanost, citiranje literature, Vancouvrski citatni stil
Published in DiRROS: 24.04.2024; Views: 171; Downloads: 38
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