16 research outputs found
Zagrożenia współczesnej rodziny: wieloaspektowość pomocy instytucjonalno-prawnej
Z wprowadzenia: "Zebrane w niniejszym tomie artykuły nie stanowią monolitycznej całości.
Ukazują raczej różnorodność problemów, a ich autorzy sygnalizują
konieczność dokładniejszej analizy obszarów zagrożeń stojących
przed rodziną, a także sformułowania zadań instytucji powołanych do
niesienia pomocy rodzinie w zwalczaniu tych zagrożeń."(...
Impact of bias field correction on 0.35 T pelvic MR images: evaluation on generative adversarial network-based OARs’ auto-segmentation and visual grading assessment
PurposeMagnetic resonance imaging (MRI)-guided radiotherapy enables adaptive treatment plans based on daily anatomical changes and accurate organ visualization. However, the bias field artifact can compromise image quality, affecting diagnostic accuracy and quantitative analyses. This study aims to assess the impact of bias field correction on 0.35 T pelvis MRIs by evaluating clinical anatomy visualization and generative adversarial network (GAN) auto-segmentation performance.Materials and methods3D simulation MRIs from 60 prostate cancer patients treated on MR-Linac (0.35 T) were collected and preprocessed with the N4ITK algorithm for bias field correction. A 3D GAN architecture was trained, validated, and tested on 40, 10, and 10 patients, respectively, to auto-segment the organs at risk (OARs) rectum and bladder. The GAN was trained and evaluated either with the original or the bias-corrected MRIs. The Dice similarity coefficient (DSC) and 95th percentile Hausdorff distance (HD95th) were computed for the segmented volumes of each patient. The Wilcoxon signed-rank test assessed the statistical difference of the metrics within OARs, both with and without bias field correction. Five radiation oncologists blindly scored 22 randomly chosen patients in terms of overall image quality and visibility of boundaries (prostate, rectum, bladder, seminal vesicles) of the original and bias-corrected MRIs. Bennett’s S score and Fleiss’ kappa were used to assess the pairwise interrater agreement and the interrater agreement among all the observers, respectively.ResultsIn the test set, the GAN trained and evaluated on original and bias-corrected MRIs showed DSC/HD95th of 0.92/5.63 mm and 0.92/5.91 mm for the bladder and 0.84/10.61 mm and 0.83/9.71 mm for the rectum. No statistical differences in the distribution of the evaluation metrics were found neither for the bladder (DSC: p = 0.07; HD95th: p = 0.35) nor for the rectum (DSC: p = 0.32; HD95th: p = 0.63). From the clinical visual grading assessment, the bias-corrected MRI resulted mostly in either no change or an improvement of the image quality and visualization of the organs’ boundaries compared with the original MRI.ConclusionThe bias field correction did not improve the anatomy visualization from a clinical point of view and the OARs’ auto-segmentation outputs generated by the GAN
W poszukiwaniu jakości życia współczesnej rodziny polskiej
Praca recenzowana / peer-reveiwed pape
Dylematy współczesnego wychowania i edukacji
Publikacja recenzowana / Peer-reviewed publicationZe wstępu: Tematyka tomu koncentruje się wokół kluczowych problemów współczesnej
oświaty i efektywnych sposobów ich przezwyciężania. Autorzy podjęli
problemy dotyczące zagadnień metodologicznych, kontekstów wychowania
szkolnego, dydaktyki szkoły wyższej, pedagogiki rodziny, kształcenia
nauczycieli oraz zagadnień związanych z tłem społecznym i politycznym
edukacji, a także uwarunkowaniami współczesnej edukacji. Dyskutowano
też kwestie teleologii edukacji, określania jej celów ogólnych, pośrednich,
szczegółowych i operacyjnych. Wymiana poglądów objęła również problematykę
trwających przemian merytorycznych i reform strukturalnych
w niektórych systemach oświatowych
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)
In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field
Studium możliwości monitorowania zasięgu wiązki w radioterapii protonowej za pomocą tomografu J-PET
Celem tej pracy było wyznaczenie liczby izotopów podlegających rozpadom prowadzącym do anihilacji pozytonu i elektronu produkowanych podczas naświetlania bloku PMMA wiązką protonów. Zbadano wydajność materiału scyntylacyjnego z którego zbudowane są elementy detekcyjne skanera oraz prawdopodobieństwo zarejestrowania pary kwantów gamma w koincydencji. Wyznaczono również rozdzielczość przestrzenną obrazu punktowego źródła, emitującego pary kwantów gamma, uzyskanego dwumodułowym tomografem J-PET. Testowane były dwa modele z różnymi wymiarami pasków. Wszystkie rozważania były oparte na symulacjach przeprowadzonych przy użyciu oprogramowania \emph{GATE}.\\Liczby najważniejszych dla obrazowania izotopów powstających podczas naświetlania bloku z PMMA wiązką 10 protonów o energiach 175 MeV, czyli O, C i C wynoszą odpowiednio 1.84, 4.47, 4.69. Prawdopodobieństwo detekcji anihilacyjnego kwantu gamma przez 2.5 cm warstwę materiału scyntlacyjnego używanego w tomografie J-PET wynosi 22.7\%. Rozdzielczość przestrzenna punktowego źródła kwantów gamma, umieszczonego w geometrycznym środku dwumodułowego tomografu została opisana poprzez tzw. \emph{Point Spread Function} (PSF) w trzech wymiarach: - wzdłuż osi detektora, ,- w płaszczyźnie prostopadłej do osi detektora. Dla paska o rozmiarach 0.6\cross 2.5\cross 50 cm i odległości między modułami 20 cm, rozdzielczość wynosi: PSF cm, PSF cm, PSF cm, dla paska o wymiarach 0.3\cross 1\cross 50 cm i odległości między modułami 20 cm, wynikiem są wartości: PSF cm, PSF cm, PSF cm.The aim of this work was to determine amount of positron emitters produced in block made of poly methyl methacrylate (PMMA) during proton beam irradiation, check detection efficiency for registartion of annihilation gamma quanta with the plastic J-PET (Jagiellonian Positron Emission Tomography) tomograph and to find spatial resolution of such a scanner. Simulations were prepared using \emph{GATE} software.\\Obtained numbers of most significant for imaging isotopes: O, C and C for proton beam with energy 175 MeV that consists of 10 protons, are respectively 1.84 , 4.47, 4.69. Efficiency for registration of gamma quanta by 2.5 cm thick layer of scintilation material used in J-PET scanner is at the level of 22.7\%. Spatial resolution of point source, that emits pairs of gamma quanta with energy 511 keV and is placed at the centre of two modules system (one module consists of ten plastic strips), was defined by point spread function (PSF) in three dimensions: - along detector, ,- transversal to detector. For a strip size 0.6\cross 2.5\cross 50 cm and the distance between modules of 20 cm results are: PSF cm, PSF cm, PSF cm and for a strip size 0.3\cross 1\cross 50 cm and distance between modules of 20 cm results are: PSF cm, PSF cm, PSF cm
Assessment of intrafractional prostate motion and its dosimetric impact in MRI-guided online adaptive radiotherapy with gating
Purpose This study aimed to evaluate the intrafractional prostate motion captured during gated magnetic resonance imaging (MRI)-guided online adaptive radiotherapy for prostate cancer and analyze its impact on the delivered dose as well as the effect of gating. Methods Sagittal 2D cine-MRI scans were acquired at 4 Hz during treatment at a ViewRay MRIdian (ViewRay Inc., Oakwood Village, OH, USA) MR linac. Prostate shifts in anterior-posterior (AP) and superior-inferior (SI) directions were extracted separately. Using the static dose cloud approximation, the planned fractional dose was shifted according to the 2D gated motion (residual motion in gating window) to estimate the delivered dose by superimposing and averaging the shifted dose volumes. The dose of a hypothetical non-gated delivery was reconstructed similarly using the non-gated motion. For the clinical target volume (CTV), rectum, and bladder, dose-volume histogram parameters of the planned and reconstructed doses were compared. Results In total, 174 fractions (15.7 h of cine-MRI) from 10 patients were evaluated. The average (+/- 1 sigma) non-gated prostate motion was 0.6 +/- 1.0 mm in the AP and 0.0 +/- 0.6 mm in the SI direction with respect to the centroid position of the gating boundary. 95% of the shifts were within [-3.5, 2.7] mm in the AP and [-2.9, 3.2] mm in the SI direction. For the gated treatment and averaged over all fractions, CTV D-98% decreased by less than 2% for all patients. The rectum and the bladder D-2% increased by less than 3% and 0.5%, respectively. Doses reconstructed for gated and non-gated delivery were similar for most fractions. Conclusion A pipeline for extraction of prostate motion during gated MRI-guided radiotherapy based on 2D cine-MRI was implemented. The 2D motion data enabled an approximate estimation of the delivered dose. For the majority of fractions, the benefit of gating was negligible, and clinical dosimetric constraints were met, indicating safety of the currently adopted gated MRI-guided treatment workflow
ScatterNet for projection-based 4D cone-beam computed tomography intensity correction of lung cancer patients
Background and purpose:In radiotherapy, dose calculations based on 4D cone beam CTs (4DCBCTs) require image intensity corrections. This retrospective study compared the dose calculation accuracy of a deep learning, projection-based scatter correction workflow (ScatterNet), to slower workflows: conventional 4D projection-based scatter correction (CBCTcor) and a deformable image registration (DIR)-based method (4DvCT).Materials and methods:For 26 lung cancer patients, planning CTs (pCTs), 4DCTs and CBCT projections were available. ScatterNet was trained with pairs of raw and corrected CBCT projections. Corrected projections from ScatterNet and the conventional workflow were reconstructed using MA-ROOSTER, yielding 4DCBCTSN and 4DCBCTcor. The 4DvCT was generated by 4DCT to 4DCBCT DIR, as part of the 4DCBCTcor workflow. Robust intensity modulated proton therapy treatment plans were created on free-breathing pCTs. 4DCBCTSN was compared to 4DCBCTcor and the 4DvCT in terms of image quality and dose calculation accuracy (dose-volume-histogram parameters and 3%/3mm gamma analysis).Results:4DCBCTSN resulted in an average mean absolute error of 87HU and 102HU when compared to 4DCBCTcor and 4DvCT respectively. High agreement was observed in targets with median dose differences of 0.4Gy (4DCBCTSN-4DCBCTcor) and 0.3Gy (4DCBCTSN-4DvCT). The gamma analysis showed high average 3%/3mm pass rates of 96% for both 4DCBCTSN vs. 4DCBCTcor and 4DCBCTSN vs. 4DvCT.Conclusions:Accurate 4D dose calculations are feasible for lung cancer patients using ScatterNet for 4DCBCT correction. Average scatter correction times could be reduced from 10min (4DCBCTcor) to 3.9s, showing the clinical suitability of the proposed deep learning-based method
Impact of secondary particles on the magnetic field generated by a proton pencil beam: a finite-element analysis based on Geant4-DNA simulations
PurposeTo investigate the static magnetic field generated by a proton pencil beam as a candidate for range verification by means of Monte Carlo simulations, thereby improving upon existing analytical calculations. We focus on the impact of statistical current fluctuations and secondary protons and electrons. MethodsWe considered a pulsed beam (10 mu{\umu}s pulse duration) during the duty cycle with a peak beam current of 0.2 mu\umuA and an initial energy of 100 MeV. We ran Geant4-DNA Monte Carlo simulations of a proton pencil beam in water and extracted independent particle phase spaces. We calculated longitudinal and radial current density of protons and electrons, serving as an input for a magnetic field estimation based on a finite element analysis in a cylindrical geometry. We made sure to allow for non-solenoidal current densities as is the case of a stopping proton beam. ResultsThe rising proton charge density toward the range is not perturbed by energy straggling and only lowered through nuclear reactions by up to 15%, leading to an approximately constant longitudinal current. Their relative low density however (at most 0.37 protons/mm(3) for the 0.2 mu{\umu}A current and a beam cross-section of 2.5 mm), gives rise to considerable current density fluctuations. The radial proton current resulting from lateral scattering and being two orders of magnitude weaker than the longitudinal current is subject to even stronger fluctuations. Secondary electrons with energies above 10 eV, that far outnumber the primary protons, reduce the primary proton current by only 10% due to their largely isotropic flow. A small fraction of electrons (<1%), undergoing head-on collisions, constitutes the relevant electron current. In the far-field, both contributions to the magnetic field strength (longitudinal and lateral) are independent of the beam spot size. We also find that the nuclear reaction-related losses cause a shift of 1.3 mm to the magnetic field profile relative to the actual range, which is further enlarged to 2.4 mm by the electron current (at a distance of rho=50 mm away from the central beam axis). For rho>45\rho >45 mm, the shift increases linearly. While the current density variations cause significant magnetic field uncertainty close to the central beam axis with a relative standard deviation (RSD) close to 100%, they average out at a distance of 10 cm, where the RSD of the total magnetic field drops below 2%. ConclusionsWith the small influence of the secondary electrons together with the low RSD, our analysis encourages an experimental detection of the magnetic field through sensitive instrumentation, such as optical magnetometry or SQUIDs