To evaluate the impact of dwell time deviation constraint (DTDC) on the quality of IPSA-optimized treatment plans in comparison with graphical plans using plan quality scores (PQS).
Seventy optimized ...plans (graphical & IPSA with different DTDC values) of ten cervical cancer patients were generated. Various DVH parameters like D90, V100, V150, V200, V300 were compared to evaluate the impact of DTDC on target coverage and high dose regions inside target for different plans. Similarly, for the OAR dose, values of D2cc were compared. Various planning parameters like CI, COIN, DHI, DNR, ODI, EI and gain factor (GF) for different OARs were calculated. Based on these indices a plan quality score (PQS) was formulated and calculated. PQS values were used to see the impact of DTDC on plan quality of IPSA in comparison with dosimetric quality of graphical plan.
We have found that target coverage is similar for IPSA and graphically optimized treatment plans. However, dose homogeneity was improved in IPSA compared to graphical optimization whereas conformality was better in graphically optimized plans. OAR dose was less in IPSA plans. High-dose regions inside the target were also reduced in IPSA comparatively. However, IPSA plans optimized with various values of DTDC did not necessarily reduce high-dose regions beyond 0.6. Plan quality scores (PQS) were 6.31, 6.31, 6.34, and 6.17 for the graphically optimized plan, IPSA with DTDC values of 0.0, 0.4, and 1.0 respectively.
We found that IPSA is dosimetrically advantageous over graphical optimization. IPSA with a DTDC value of 0.4 improved overall plan quality. However, DTDC value beyond 0.6 produces dosimetrically sub-optimal plans hence the use of DTDC should be very selective and limited.
Évaluer l’impact de la contrainte d’écart de temps d’arrêt de la source (DTDC) sur la qualité des plans de traitement optimisés IPSA (Inverse Planning by Simulated Annealing) par rapport aux plans graphiques utilisant des scores de qualité de plan (PQS).
Soixante-dix plans optimisés (graphiques et IPSA avec différentes valeurs de DTDC) de dix patientes atteintes d’un cancer du col de l’utérus ont été générés. Divers paramètres de l’histogramme dose-volume tels que la D90 (dose reçue par 90 % du volume), les V100, V150, V200, V300 (Vx: volume recevant x Gy) ont été comparés pour évaluer l’impact de la DTDC sur la couverture de la cible et les régions à forte dose à l’intérieur de la cible pour différents plans. De même, pour les organes à risque, les valeurs de D2cc (dose reçue par 2cc) ont été comparées. Divers paramètres de planification tels que les Coverage Index (CI), Conformity Index (COIN), Dose Homogeneity Index (DHI), Dose Non-uniformity index (DNR), Over-Dose Volume index (ODI), External Volume index (EI) et le facteur de gain (GF) ont été calculés pour différents organes à risque. Sur la base de ces indices, un score de qualité du plan (PQS) a été formulé et calculé. Les valeurs de PQS ont été utilisées pour voir l’impact de la DTDC sur la qualité du plan de l’IPSA par rapport à la qualité dosimétrique du plan graphique.
Nous avons constaté que la couverture cible est similaire pour les plans de traitement IPSA et graphiquement optimisés. Cependant, l’homogénéité de la dose était améliorée dans l’IPSA par rapport à l’optimisation graphique, tandis que la conformité était meilleure dans les plans optimisés graphiquement. La dose dans les organes à risque était moindre dans les plans IPSA. Les régions à forte dose à l’intérieur de la cible ont également été réduites dans l’IPSA comparativement. Cependant, les plans IPSA optimisés avec diverses valeurs de DTDC ne réduisaient pas nécessairement les régions à forte dose au-delà de 0,6. Les scores de qualité du plan (PQS) étaient de 6,31, 6,31, 6,34 et 6,17 pour le plan optimisé graphiquement IPSA, avec des valeurs de DTDC respectivement de 0,0, 0,4 et 1,0 r.
Nous avons constaté que l’IPSA est dosimétriquement avantageux par rapport à l’optimisation graphique. L’IPSA avec une valeur de DTDC de 0,4 a amélioré la qualité globale du plan. Cependant, une valeur de DTDC au-delà de 0,6 produit des plans dosimétriquement sous-optimaux, par conséquent l’utilisation de la DTDC doit être très sélective et limitée.
Cryogenically cooled solid-state lasers promise a revolution in power scalability while maintaining a good beam quality because of significant improvements in efficiency and thermo-optic properties. ...This is particularly true for Yb lasers because of their relatively low quantum defect and relatively broadband absorption even at cryogenic temperatures. Thermo-optic properties of host materials, including thermal conductivity, thermal expansion, and refractive index at low temperature, are reviewed and data presented for YAG (ceramic and single crystal), GGG, GdVO 4 , and Y 2 O 3 . Spectroscopic properties of Yb:YAG and Yb:LiYF 4 (YLF) including absorption cross sections, emission cross sections, and fluorescence lifetimes at cryogenic temperatures are characterized. Recent experiments have pushed the power from an end-pumped cryogenically cooled Yb:YAG laser to 455-W continuous-wave output power from 640-W incident pump power at an of M 2 1.4.
Thermooptic effects often limit the power and beam quality of bulk-solid-state lasers. Cryogenically cooled (/spl sim/100 K) Yb:YAG lasers have been previously demonstrated to have relatively low ...thermooptic effects and high efficiency due to improved material properties at low temperatures. In this work, >300-W average power with M/sup 2//spl sim/1.2 and 64% optical-optical efficiency has been demonstrated from an end-pumped-rod geometry power oscillator. To our knowledge, this is the highest average power to date from a cryogenically cooled Yb:YAG laser.
An epoxy–cardanol resin was developed using epichlorohydrin, bisphenol-A and cardanol. On evaluation it was found that epoxy–cardanol resin exhibits better properties as compared to epoxy resin in ...terms of increase in tensile strength, elongation, bond with steel and lowering of water vapour transmission of the film. The improvement in these properties indicated that the paints based on modified resin would be more durable than the epoxy based paints. Accordingly, paints were formulated using the developed resin and their performance were compared with their counterparts made with unmodified epoxy resin. Zinc powder, zinc phosphate, micaceous iron oxide and synthetic iron oxide were used as pigments along with fillers, additives and an aromatic polyamine adduct hardener. For both types of paints similar doses of pigments and additives were used. Physico-mechanical properties, chemical resistance and corrosion protection efficiency of the formulated paints were determined. It was found that the anticorrosive properties of epoxy–cardanol resin based paints are superior to that of the paints formulated with the unmodified epoxy resin. Micaceous iron oxide based paints in epoxy–cardanol resin showed the best performance followed by zinc phosphate based paints. It is concluded that the developed resin is a better binder media for the formulation of paints.
Abstract
A spring steel leaf spring is commonly used for suspension system in all types of loading vehicles due to its good stiffness and fatigue strength. Today, spring steel leaf springs are used ...in majority of applications but they are heavy in weight, poor in terms of gets corrosion resistance and average in ride comfort. Fiber reinforced composite material leaf spring represents a key application of composite materials in the field of automotive vehicles due to improved ride comfort and light in weight. Stiffness, fatigue life and damping capacity are the critical parameter of fiber reinforced composite leaf springs. CAE software and experimental analysis have been mainly used for design and analysis for composite material leaf springs. Saman Jolaiy et.al. 2021 focused on the damping characteristics of the composite leaf springs and worked out that fabrication of composite leaf spring with viscoelastic core(2mm) decreases the damping ratio of the leaf spring system, which results in a smooth ride. Few studies evaluated the stress distribution, deflection and fatigue life assessment of composite leaf springs reinforced with glass fibers or carbon fibers or combination of carbon lass and carbon fibers. The main objective of the present work is to optimize various percentage of fiber reinforced composite material leaf springs along with insertion of viscous core. The optimized results thus obtained show that the fiber reinforced composite leaf springs with viscous core can be a good replacement of spring steel leaf springs with overall weight reduction and better damping characteristics. Replacing spring steel leaf springs with fiber reinforced composite leaf springs will improve safety, comfort, high elastic strain energy storage capacity and durability.
Abstract
Leaf Springs finds vast applications in different types of mechanical systems. In spite of lot of research, spring steel leaf springs finds a lot of applications in all types of heavy ...vehicle. Composite leaf springs represent some application of composite materials in the field of automotive lightweight materials. However, the composite material finds limited applications in the form of mono leaf but for multi leaf in heavy vehicles, its application is rare due to certain issues including delamination. Stiffness and damping properties are the critical parameter of composite leaf springs and are closely related to the handling stability and ride comfort of automobiles. Composite leaf spring with variable parameters may be used in the automobiles to replace the conventional steel leaf springs, mainly due to the high load-bearing capacity. The optimum structural design of composite leaf spring may be calculated using an effective algorithm. The mechanical properties of composite leaf spring is analyzed with experimental or computational approach or both. This paper investigates addresses various issues regarding the replacement of composite material leaf springs with spring steel leaf springs in light and heavy weight automotive vehicles.
A lot of research has been done to improve fatigue strength of materials by creating compressive residual stress field in their surface layers through shot peening. In this paper, fatigue strength of ...shot peened leaf springs has been calculated from laboratory samples. The axial fatigue strength of EN45A spring steel specimen is evaluated experimentally as a function of shot peening in the conditions used for full-scale leaf springs testing in industries. Optimum shot peening condition for specimen is found and
S/
N curves of the specimens are correlated with leaf springs curve. A mathematical model has been developed which predicts the fatigue life of leaf springs for a given stress at varying shot peening conditions. Predictions from this model are compared with experimental data. The estimation of fatigue life and relaxation of compressive residual stress field are discussed.
Classical restriction fragment length polymorphism (RFLP) and sequencing are labor-intensive and expensive methods to study single base changes, whereas polymerase chain reaction amplification of ...specific alleles (PASA) or allele-specific polymerase chain reaction (ASPCR) is a PCR-based application that allows direct detection of any point mutation by analyzing the PCR products in an ethidium bromide-stained agarose or polyacrylamide gel. PASA is based on oligonucleotide primers containing one or more 3' mismatch with the target DNA making it refractory to primer extension by Thermus aquaticus DNA polymerase lacking the 3' to 5' exonuclease proofreading activity because of which it is also called amplification refractory mutation system-PCR (ARMS-PCR). This technique has found application in detection of allele, mutation, single-nucleotide polymorphisms (SNPs) causing genetic and infectious diseases. This chapter describes an approach of cohort PASA in context of genotyping single and double mutant worms generated to study the process of cell migration and axon outgrowth in C. elegans. Single worm-based cohort PASA allows genotyping for identification of single base mutations; particularly it is convenient method to detect mutations without a visible phenotype.
This study investigates basic dosimetric properties of unflattened 6 MV photon beam shaped by multileaf collimator and compares them with those of flattened beams.
Monte Carlo simulation model using ...BEAM code was developed for a 6MV photon beam based on Varian Clinic 600 unique performance linac operated with and without a flattening filter in beam line. Dosimetric features including lateral profiles, central axis depth dose, photon and electron spectra were calculated for flattened and unflattened cases, separately.
An increase in absolute depth dose with a factor of more than 2.4 was observed for unflattened beam which was dependent on depth. PDDs values were found to be lower for unflattened beam for all field sizes. Significant decrease in calculated mlc leakage was observed when the flattening filter was removed from the beam line. The total scatter factor, S
was found to show less variation with field sizes for unflattened beam indicating a decrease in head scatter. The beam profiles for unflattened case are found to have lower relative dose value in comparison with flattened beam near the field edge, and it falls off faster with distance.
Our study showed that increase in the dose rate and lower peripheral dose could be considered as realistic advantages for unflattened 6MV photon beams.
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