Empirical modeling of the percent depth dose for megavoltage photon beams

Introduction This study presents an empirical method to model the high-energy photon beam percent depth dose (PDD) curve by using the home-generated buildup function and tail function (buildup-tail function) in radiation therapy. The modeling parameters n and μ of buildup-tail function can be used to characterize the Collimator Scatter Factor (Sc) either in a square field or in the different individual upper jaw and lower jaw setting separately for individual monitor unit check. Methods and materials The PDD curves for four high-energy photon beams were modeled by the buildup and tail function in this study. The buildup function was a quadratic function in the form of dd2+n with the main parameter of d (depth in water) and n, while the tail function was in the form of e−μd and was composed by an exponential function with the main parameter of d and μ. The PDD was the product of buildup and tail function, PDD = dd2+n·e−μd. The PDD of four-photon energies was characterized by the buildup-tail function by adjusting the parameters n and μ. The Sc of 6 MV and 10 MV can then be expressed simply by the modeling parameters n and μ. Results The main parameters n increases in buildup-tail function when photon energy increased. The physical meaning of the parameter n expresses the beam hardening of photon energy in PDD. The fitting results of parameters n in the buildup function are 0.17, 0.208, 0.495, 1.2 of four-photon energies, 4 MV, 6 MV, 10 MV, 18 MV, respectively. The parameter μ can be treated as attenuation coefficient in tail function and decreases when photon energy increased. The fitting results of parameters μ in the tail function are 0.065, 0.0515, 0.0458, 0.0422 of four-photon energies, 4 MV, 6 MV, 10 MV, 18 MV, respectively. The values of n and μ obtained from the fitted buildup-tail function were applied into an analytical formula of Sc = nE(S)0.63μE to get the collimator to scatter factor Sc for 6 and 10 MV photon beam, while nE, μE, S denotes n, μ at photon energy E of field size S, respectively. The calculated Sc were compared with the measured data and showed agreement at different field sizes to within ±1.5%. Conclusions We proposed a model incorporating a two-parameter formula which can improve the fitting accuracy to be better than 1.5% maximum error for describing the PDD in different photon energies used in clinical setting. This model can be used to parameterize the Sc factors for some clinical requirements. The modeling parameters n and μ can be used to predict the Sc in either square field or individual jaws opening asymmetrically for treatment monitor unit double-check in dose calculation. The technique developed in this study can also be used for systematic or random errors in the QA program, thus improves the clinical dose computation accuracy for patient treatment.

SURVIVAL RATE of TIGER GROUPER LARVA (Epinephelus fucoguttatus) HOUSEHOLD SCALE ON THE NORTH COAST of BALI

Tiger grouper (Epinephelus fuscoguttatus) hatchery at the household scale has contributed to the increase in national grouper seed production. The main problem in tiger grouper cultivation is the availability of superior seeds. Where superior tiger grouper seeds must have fast growth, be resistant to new environments, low FCR, have perfect morphology and be resistant to. Superior seeds of tiger grouper can be seen from the value of Survival Rate (SR), where superior seeds will have a much higher SR when maintained. The purpose of this study was to determine the Survival Rate of tiger grouper hatchery in household-scale hatcheries located on the North Coast of Bali as the main parameter and water quality as a supporting parameter. Methods of data collection is done by using 4 ways: survey, active participation, observation, and interviews. Survival rate data analysis was carried out by performing calculations based on the SR calculation formula and analyzed descriptively. The results of observations of water quality are classified as good for the value of Salinity (33-35 ppt), Temperature (28-29.4 oC), and DO (6-6.5 ppm). While the pH value can be said to be not good for tiger grouper hatchery and rearing with a pH value of (7.3-7.4). The result of the calculation of the Survival Rate is 20% with a total of ± 24,000 seeds. From the percentage of survival rate, it can be said that the survival rate of tiger grouper larvae in this household-scale hatchery is still low. However, it should be noted that a low survival rate in grouper hatcheries does not always affect the value of profits and losses of a grouper hatchery business.

RANCANG BANGUN KOMPONEN UTAMA PLTS OFF-GRID UNTUK MENUNJANG OPERASI INCINERATOR SIPESAT®

To increase reliability of SIPESAT® Incinerator, off-grid solar powerplant was installed. The aim of this paper is to designing the requirement of the main equipment for the solar powerplant. 270 w, 3 autonomies days were used as the main parameter. GHI gathered from NASA’s data, VRLA battery type with MPPT inverter type was chosen to design the solar powerplant system. based on calculation results, the solar powerplant system need two solar panels 150watt each, and two VRLA battery 24V 200 Ah each,

HIGH-TEMPERATURE CONSOLIDATION AS A STRUCTURE CONTROL METHOD OF THE NANOPOROUS GLASSES

Nanoporous glass is a matrix for composite optical materials, in which, by impregnating various activators, it is possible to initiate the appearance of properties that are uncharacteristic for the composite materials. In this case, the main parameter of the structure of nanoporous glass is porosity, which can be controlled by the method of high-temperature consolidation. In this work, we have studied the effect of temperature consolidation on the structure of porous glass.

Research of model tests of parameters move-ment of the goat crane under action of load loads

The results of experimental researches of parameters of movement of the model of the gantry crane under the influence of wind loadings are resulted. The assessment of the accuracy and reliability of the obtained results is performed and further directions of research are outlined. The adopted test program included the definition of similarity criteria and scale of the model, where the main parameter was the speed of the crane when exposed to wind. The influence of various factors and assessment of the impact of their interaction was achieved by conducting PFE type 24.

An Analytical Approach to Obtaining the Stress Field of a Cylindrical Shell with a Circular Hole under Tension

The problem of a cylindrical shell with a circular hole under uniaxial tension is considered. The main obstacle of solving this problem is the necessity to find such coefficients in the expansion of the solution into a sum of basis functions, for which this solution satisfies the boundary conditions. The study of the classical works led to understanding that none of the so far proposed approaches can be considered successfully, and the results of these approaches differ, so it is not clear, which results can be used as a basis. In the present paper, a new analytical approach to studying this issue is proposed. It allows expanding the range of applicability of the solution and gives the opportunity for the analytical study of the stress state. The idea consists in expanding each of the basis functions in a Fourier series by dividing the variables, which allows obtaining explicitly an infinite system of algebraic equations for finding coefficients. One of the important steps of this research is that the authors were able to prove which exact equation is a linear combination of the others and exclude, which made it possible to compose a reduced system for finding unknown coefficients. The proposed approach, in contrast to most classical works, does not impose mathematical restrictions on the values of the main parameter characterizing the cylindrical shell. The existing restrictions are of mechanical nature, as larger cutouts require another model. Moreover, the numerical results obtained by the new method are presented in a fairly complete manner and they are compared with the results of the classical works.

Trends of pH and aerosols in the precipitation at Srinagar, Mohanbari, Allahabad, Jodhpur, Nagpur and Minicoy during the period 1981-2001

Nature of Precipitation - alkaline or acidic depends upon the concentration of major water soluble inorganic gaseous and soil derived particulates dissolved in it. If the concentration of cations is higher than that of anions the precipitations becomes alkaline and vice versa. pH is the main parameter indicating the nature of precipitation. If pH of rainwater <5.65 it is acidic and >5.65, it is alkaline ,both in the pH scale ranging between 0 and 14. In this paper average ionic concentration (mg/lit) and their trends have been analyzed. Srinagar, Mohanbari, Jodhpur, Allahabad, Nagpur and Minicoy have been selected for the study of chemical precipitation during the period 1981-2001. Trends of different aerosols have been analyzed at the intervals 1981-87, 1988-94 and 1995-2001. It has been observed that percentage of anions has increased which results in the increase of acidic character of the precipitation. During the interval 1995-2001, Nagpur and Mohanbari had pH values 5.16 and 5.47 respectively which were in acidic range.

A Corpus of Czech Essays from the Turn of the 1900s

A literary essay is an interesting unit for language analyses, as its stylistic means often exceed the boundaries of the genre of an artistic essay. The article presents a new corpus of Czech literary essays covering approximately fifty years from 1890 to 1940. Along with the characterisation of the corpus and its annotation, the paper focuses on the TxM corpus tool: In the second part of the study, we use selected texts to conduct an analysis of seven various authors through multidimensional cluster analysis, factorial correspondence analysis and a specificity score. The main parameter of the analyses was usage of parts of speech in texts by individual authors. At present, the Corpus of Czech Essays contains 40 essayist titles written by 15 authors covering various topics (music, visual arts, theatre, literature, etc.).

Influence of paper properties on adhesive strength of starch gluing

The effect of paper properties on the strength of starch gluing for Kraft sack papers has been investigated. We analyzed the effect of surface roughness, wettability and glue penetration. Surface roughness was found not to be related to gluing strength, also surface wetting measured by contact angle showed only a weak relation. Liquid penetration measured by ultrasound (ULP) was found to have a substantial correlation to gluing strength. Comparing ULP liquid penetration speed with actual glue uptake during the gluing process we found that they are only moderately connected. We are attributing this to the fact that the penetration and spreading of the glue on the paper is driven by applying an external pressure during the gluing process, which is not the case for the liquid penetration measurement. Investigating how asymmetrical glue penetration affects gluing strength we found that the relationship was low. The best indication for gluing strength turned out to be the surface wetting/substrate swelling parameter from the ultrasonic liquid penetration measurement. We conclude that the main parameter capturing gluing strength combines the influence of fiber wetting and penetration of the glue into the fibers.