Empirical Formalism for the Phantom Scatter Factor of Small Fields: Using Different Density Media

We present the Empirical Formula (EF) to calculate the phantom scatter factor, Sp, of small radiation fields under charge particle dis-equilibrium conditions. The Empirical Formula (EF) was verified by examining the calculated data with experimentally measured data utilizing the anthropomorphic phantom in twelve different combinations of beam entry and point location, where the value for Sp per tissue composition was within 3% in 8/12 cases, 5% in 1/12 cases, and 10% in 3/12 cases. Our results showed a good agreement with experimental data to less than 1% when the ion chamber was surrounded by the homogeneous tissue, whether lung, soft tissue, or bone. Indicating that the prediction of the equation is valid, and it can be reliably used for phantom scatter factor calculation for different homogeneous media under charge particle dis- equilibrium conditions.

“Eternal Motion” as a “Form of Movement of a Special Nature” and the Main Condition for the Creation of the Universe

The article hypothesizes that DE and DM (UCM) are a “Form of Motion of a Special Nature”, where “Form of Motion” means “Eternal Motion” as the power of dynamics of different levels and varying degrees of self-sufficiency, and by “Special Nature”, gravitational and two other properties of matter, “tied” to the “Eternal Movement” and completely dependent on it. Carriers of key properties of a “Special Nature” have been established: “0”-DE particles and “3”-DM particles (UDM). The unity of their inherent “motionally-gravitational” properties and the peculiarity of the relationship between “motion” and “gravity” are revealed: the higher the intensity of “Eternal Motion”, the stronger the gravitational properties of matter are manifested (and vice versa). The relationship of “time” with the “vibration frequency” and the “mass” of photons with the “degree of bonding and deformation properties of the field” is shown. The maximum level of gravity has been determined, which allows Nature to successfully create the Universe: such a landmark is the proximity to the property of the Primary Source—the “pure graviton” of the OSP space, the most powerful “motionally-gravitational” particle of the Universe. The reasons for the emergence of such an identity of the gravitational properties of particles with the indicators of a “pure graviton” are established: for “0”-DE particles, this is the acquisition of the function of “freedom of movement”;for “3”-DM particles (UDM), the creation of a special structure—a “double field” (“Main” and “Small”). The presence in the “double field” of specific “tools” for the creation of the worlds of the Universe—gravitational “waves” gives rise to impulses (shocks) of varying intensity and shape. A list of functions performed by “waves” in the “Main” and “Small” fields has been compiled. The specific conditions for the formation of “UDM Streams”, their transformation into a “Vortex” and, under the influence of a powerful Initial Impulse (push), sending them to the “place” of the creation of galaxies, are shown. It is suggested that there is a “Cycle of Matter in Nature” in the closed structure of our Universe due to the “work” of “waves” and the functioning of special “factories” in the form of exotic space objects—Black holes.

A Gamma Analysis Approach to Determine Optimal Parameters for Monte Carlo Simulation of 6MV Varian Clinac iX Photon Beam

Monte Carlo （MC） method is the gold standard dose calculation algorithm. Determination of the electron beam parameters for MC simulation is often estimated using trial and error methods. However, this can be tedious and time-consuming. This paper aims to validate MC simulated data using 1D gamma analysis for 6MV photon beam to obtain the optimal parameters. BEAMnrc codes were used to generate phase space files for conventional field sizes 10 × 10 cm^2, 6 × 6 cm^2, 4 × 4 cm^2 and small field sizes 2 ×2 cm^2, 1 ×1 cm^2, 0.5 ×0.5 cm^2. For conventional field sizes, simulations were benchmarked against Golden Beam Data （GBD）. Simulations for small fields were benchmarked against measurements obtained using EDGE Detector and PTW Diode SRS detector in a Sun Nuclear 3D scanner. Dose profiles in water were calculated using DOSXYZnrc codes. Initial reference parameters were approximated using average percentage dose differences of different mean electron energy and electron beam radial distribution （Full Width at Half Maximum, FWHM）. Subsequently, the optimal parameters were validated by 1D gamma analysis using varying gamma criteria from γ3%%/0.3mm to γ2.0%/2.0mm for depth dose and lateral dose profiles. Comparisons were performed along the central region at depth dose 1.6 cm . Optimal parameters were found to be unique for small field sizes. As field size decreases, smaller FWHM were required to match measured data. By using 95% passing rate, a generic set of optimal electron beam parameters in a MC model for all field sizes could be accurately determined. Our findings provide MC users a set of optimal parameters with sufficient accuracy for MC simulation work.

Linear theory of beam–wave interaction in double-slot coupled cavity travelling wave tube

A three-dimensional model of the double-slot coupled cavity slow-wave structure （CCSWS） with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the ＂cold＂ dispersion, the ＂hot＂ dispersion equation is derived with the Maxwell equations by using the variable separation method and the field-matching method. Through numerical calculations, the effects of the electron beam parameters and the staggered angle between adjacent walls on the linear gain are analyzed.

Planning issues on linac-based stereotactic radiotherapy

This work aims to summarize and evaluate the current planning progress based on the linear accelerator in stereotactic radiotherapy(SRT).The specific techniques include 3-dimensional conformal radiotherapy,dynamic conformal arc therapy,intensity-modulated radiotherapy,and volumetric-modulated arc therapy(VMAT).They are all designed to deliver higher doses to the target volume while reducing damage to normal tissues;among them,VMAT shows better prospects for application.This paper reviews and summarizes several issues on the planning of SRT to provide a reference for clinical application.

Analysis of Space-time Characteristics of Energy Field of Seismicity in Jiangsu and Its Neighboring Areas

The paper analyzes the variation characteristics of energy fields of seismicity 2.1≤M L ≤4.5 in Jiangsu and its neighboring areas during the period between January 1970 and December 2007.It also analyzes the variations of time "weight" coefficients of the major typical energy fields,using random function theory with seismic energy fields as a space-time random function field based on Empirical Orthogonal Function (EOF) expansion methods.The results show that the expansion accuracy of the first seven typical fields is 0.9244.The strength of seismic energy varies remarkably in different tectonic blocks in the study area.High value areas are in middle and southern Jiangsu,and the south Yellow Sea.The distribution of the typical fields also shows that it is an area that affects most significantly the seismic energy fields of the study region.The time "weight" coefficients of the first six typical fields vary with time,and the amplitude of the variations has strong temporal correlations with moderate-strong earthquakes in the region.

Precise 3D shape measurement of three-dimensional digital image correlation for complex surfaces

Three dimensional-digital image correlation （3D-DIC） is a widely used optical metrology in the experimental mechanics community because of its reliability, practicality, and flexibility. Although the precision of digital image correlation （DIC） has been thoroughly studied theoretically and numerically, verification experiments have seldom been performed, especially fbr complex surfaces with a small field of view （FOV）. In this work, the shape of a 1-yuan coin was measured using 3D-DIC; the shape was complex due to the presence of many fine details, and the FOV was relatively small because the coin diameter was only 25 mm. During the experiment, a novel strategy for speckle production was developed： white paint was simply sprayed onto the surface. Black paint was not used; instead, taking advantage of the reflective nature of the coin surface, polarized light and a Polaroid filter were introduced, and the polarization direction was carefully adjusted, ensuring that the spray pattern was extremely thin and that high-quality speckle images with significant contrast were captured. The three-dimensional coin shape was also successfully determined for comparison using a stylus profiler. The results demonstrate that 3D-DIC provides high precision in shape measurement even for complex surfaces with small FOV. The precision of 3D-DIC can reach 1/7000 of the field of view, corresponding to about 6 ~tm in this experiment.