Vascular dementia (VD) is a degenerative cerebrovascular disorder, leading to progressive decline of cognitive abilities and memory. Rehmannioside A (ReA) is isolated from Rehmanniae Radix, which ...exhibits protective role against various diseases. The present study was performed to calculate the possible neuroprotective effects of ReA on VD. Here, the morris water maze (MWM) test and electrophysiological recordings indicated that ReA reduced cognitive deficits. Additionally, through hematoxylin and eosin (H&E) and Nissl staining, ReA attenuated the histological alterations of hippocampus in rats with VD. ReA group significantly reduced oxidative stress, inflammatory response and apoptosis in the hippocampus of rats with VD, which was linked to the activation of nuclear erythroid related factor-2 (Nrf2), while the inactivation of nuclear factor-κB (NF-κB) and Caspase-3. Further, the anti-oxidative, anti-inflammatory and anti-apoptosis abilities of ReA were confirmed in cells stimulated by hydrogen peroxide. Overall, the results above demonstrated the protective effects of ReA against cognitive deficits and indicated the potential value of ReA in the therapy of VD in future.
To use angular beam's-eye-view dosimetrics (BEVD) information to improve the computational efficiency and plan quality of inverse planning of aperture-modulated arc therapy (AMAT).
In BEVD-guided ...inverse planning, the angular space spanned by a rotational arc is represented by a large number of fixed-gantry beams with angular spacing of approximately 2.5 degrees. Each beam is assigned with an initial aperture shape determined by the beam's-eye-view (BEV) projection of the planning target volume (PTV) and an initial weight. Instead of setting the beam weights arbitrarily, which slows down the subsequent optimization process and may result in a suboptimal solution, a priori knowledge about the quality of the beam directions derived from a BEVD is adopted to initialize the weights. In the BEVD calculation, a higher score is assigned to directions that allow more dose to be delivered to the PTV without exceeding the dose tolerances of the organs at risk (OARs) and vice versa. Simulated annealing is then used to optimize the segment shapes and weights. The BEVD-guided inverse planning is demonstrated by using two clinical cases, and the results are compared with those of a conventional approach without BEVD guidance.
An a priori knowledge-guided inverse planning scheme for AMAT is established. The inclusion of BEVD guidance significantly improves the convergence behavior of AMAT inverse planning and results in much better OAR sparing as compared with the conventional approach.
BEVD-guidance facilitates AMAT treatment planning and provides a comprehensive tool to maximally use the technical capacity of the new arc therapeutic modality.
To develop a 4D volumetric modulated arc therapy (VMAT) inverse planning framework.
4D VMAT inverse planning aims to derive an aperture and weight modulated arc therapy treatment plan that optimizes ...the accumulated dose distribution from all gantry angles and breathing phases. Under an assumption that the gantry rotation and patient breathing are synchronized (i.e., there is a functional relationship between the phase of the patient breathing cycle and the beam angle), the authors compute the contribution from different respiration phases through the registration of the phased CT images. The accumulative dose distribution is optimized by iteratively adjusting the aperture shape and weight of each beam through the minimization of the planning objective function. For comparison, traditional 3D VMAT plans are also performed for the two cases and the performance of the proposed technique is demonstrated.
A framework for 4D VMAT inverse planning has been proposed. With the consideration of the extra dimension of time in VMAT, a tighter target margin can be achieved with a full duty cycle, which is otherwise not achievable simultaneously by either 3D VMAT optimization or gated VMAT.
The 4D VMAT planning formulism proposed here provides useful insight on how the "time" dimension can be exploited in rotational arc therapy to maximally compensate for the intrafraction organ motion.
This work has the purpose of validating the Monte Carlo toolkit TOol for PArticle Simulation (TOPAS) for low-dose-rate (LDR) brachytherapy uses.
Simulations of 12 LDR sources and 2 COMS eye plaques ...(10 mm and 20 mm in diameter) and comparisons with published reference data from the Carleton Laboratory for Radiotherapy Physics (CLRP), the TG-43 consensus data and the TG-129 consensus data were performed. Sources from the IROC Houston Source Registry were modeled. The OncoSeed 6711 and the SelectSeed 130.002 were also modeled for historical reasons. For each source, the dose rate constant, the radial dose function and the anisotropy functions at 0.5, 1 and 5 cm were extracted. For the eye plaques (loaded with 125I sources), dose distribution maps, dose profiles along the central axis and transverse axis were calculated.
Dose rate constants for 11 of the 12 sources are within 4% of the consensus data and within 2% of the CLRP data. The radial dose functions and anisotropy functions are mostly within 2% of the CLRP data. In average, 92% of all voxels are within 1% of the CLRP data for the eye plaques dose distributions. The dose profiles are within 0.5% (central axis) and 1% (transverse axis) of the reference data.
The TOPAS MC toolkit was validated for LDR brachytherapy applications. Single-seed and multi-seed results agree with the published reference data. TOPAS has several benefits such as a simplified approach to MC simulations and an accessible brachytherapy package including comprehensive learning resources.
•TOPAS is user-friendly by using parameter files which do not require advanced coding knowledge.•TOPAS is now a state-of-the-art Monte Carlo simulation toolkit for LDR brachytherapy.•This work provides TOPAS users with a pre-made LDR brachytherapy geometries package.•TOPAS provides a tutorial to help users create brachytherapy Monte Carlo simulations.
Research has shown that microRNAs exhibit regular dysregulation in cancers, making them potential biomarkers for cancer diagnosis. However, achieving specific and sensitive detection of microRNAs has ...been a challenging task. To address this issue, two-dimensional networked graphdiyne is used to fabricate a self-powered biosensor and establish a new approach for ultra-responsive dual-mode detection of miRNA-141, a breast cancer biomarker. This method detects miRNA-141 using both electrochemical and colorimetric modes by measuring the output electrical signal of an enzyme-based biofuel cell and the RGB blue value of the electrolyte solution. Tetrahedral DNA and DNA nanorods also are immobilized on the electrode as a biocathode and methylene blue is used as the electron acceptor, which is fixed in the DNA phosphate backbone through electrostatic adsorption. The bioanode catalyzes the oxidation of glucose to produce electrons, which reduces methylene blue to its reduced form, resulting in a high open-circuit voltage (EOCV) and a highger RGB Blue value, enabling dual-mode detection. A reliable linear correlation is observed between EOCV values and miRNA-141 concentrations ranging from 0.0001 to 100 pM, with a detection limit of 21.9 aM (S/N = 3). Additionally, the colorimetric mode also demonstrates a reliable linear correlation with a concentration range of 0.0001–10000 pM, and this method can detect a concentration of 22.2 aM (S/N = 3). This innovative research realizes sensitive and accurate determination of miRNA-141 and provides an important new method for cancer diagnosis.
Display omitted
•A novel self-powered platform is developed based on graphdiyne and DNA nanorods for ultrasensitive miRNA-141 detection.•Electrochemical/colorimetric dual-mode detection greatly improves reliability and accuracy.•The using of AuNPs/GDY, DNA nanorods and T-DNA enables amplified signal, reducing enzyme consumption and improved stability.
Monte Carlo simulation (MC) is a major type of model-based dose calculation algorithm (MBDCA) in Brachytherapy. However, due to the large number of primary beams (usually hundreds of millions or ...more) as needed to obtain small statistical errors, MC is usually not practical in clinical applications. Recently, there arise several NVIDIA CUDA-based graphic processing unit (GPU) MC codes that accelerate the simulation such that they suffice clinical requirements in certain situations. In this work, an Open-CL-based MC code that targets Brachytherapy dose calculations, OpenTRAK, was presented.
OpenTRAK implements all photon interactions (photoelectric effect, compton scatter, rayleigh scatter and pair-production) and computes the spatial energy-fluence distribution. The linear track estimator was then used to calculate the collisional kerma (Dm,m) distribution in phantom. OpenTRAK was preliminarily benchmarked against ALGEBRA, a GEant4-based BRAchytherapy dose calculation code1, by using a MicroSelectronV2 Ir-192 HDR source. The source phasespace files had been prepared before dose calculations and were used as input for both MC codes. As an preliminary test, a single source was placed in the centre of a uniform water phantom with dimension of 200×200×200mm3 with its longitudinal axis aligned with the z-axis of the phantom. Dose ratio map (DOpenTRAK/DALGEBRA) was generated and used for comparison analysis. The codes were run in a Mac Pro with two AMD FirePro D700 GPUs (for OpenTRAK) and a 2.7GHz 12-Core Intel Xeon E5 CPU (ALGEBRA).
The ratio map shows that the codes are consistent with each other with <1% deviations within the region enclosed by the 20% isodose surface. Beyond the surface, OpenTRAK shows systematic deviations due to unknown reasons. The simulation time of OpenTRAK is 1/13 of that of ALGEBRA.
An OpenCL-based MC code for brachytherapy dose calculation was implemented and preliminarily tested. The code itself needs further fine-tuning/corrections in order to maximize its GPU acceleration. Further benchmarks are planned including source TD-43 parameters extraction, real patient test cases, etc.
Geant4-DNA 1,2 is a Geant4 module that simulates the track structure of charged particles (electron/positron, proton and ions) in water as well as the radiolysis process that follows. Unlike the ...condensed-history technique in normal Geant4 simulations, Geant4-DNA implements an analogue Monte Carlo (AMC) technique that gives the event-by-event history of primary particle and all its descendants. Due to this, the simulation is extremely slow. To provide a faster alternative, this work implements a GPU-based AMC using the OpenCL parallel programming framework, OpenDNA.
For electrons and positron, ionization, excitation and elastic scattering were implemented. For protons, ionization and excitation were implemented. The low energy cut is 10eV (10keV) for electron (proton). The physical models and cross section data were extracted from Geant4-DNA. OpenDNA was preliminarily benchmarked against Geant4-DNA by radial dose distribution (RDD) simulations. For electron, a spherical geometry was used for a isotropic point source of E=30keV for both codes. For proton, a cylindrical geometry was used and a E=800keV proton was initiated along its axis. The ratio of OpenDNA RDD over Geant4-DNA RDD was computed to evaluate the consistency. 1,000,000 (and 100,000) primary histories were simulated for the electron (proton) case. The codes were run in a Mac Pro with two AMD FirePro D700 GPUs (for OpenDNA, using 100 threads) and a 2.7GHz 12-Core Intel Xeon E5 CPU (Geant-DNA).
The RDDs of OpenDNA and Geant4-DNA are consistent with each other within 1% for both particles. The simulation time of the electron (proton) case was reduced to 1/12 (1/10).
An analogue MC code was implemented using OpenCL and therefore is supposed to run in all OpenCL-conformed GPU. Future work include the simulation of physicochemical and chemical processes.
PDF
