Purpose: Modulated electron radiotherapy (MERT) has been demonstrated to be an ideal treatment for lesions close to the surface in terms of dose coverage and sparing of underlying critical organs and ...normal tissues. The purpose of this study was to obtain the parameters and devise strategies for segment matching which are necessary for efficient MERT treatment planning. Methods: In this study we used EGS4nrc/BEAMnrc and MCSim code for Monte Carlo calculations. The Computational Environment for Radiotherapy research (CERR) tool was used for viewing and comparing plans. A water phantom, delineated with stepped target idealized for two segments with sizes from 2 to 6 cm and electron beam energies of 6, 9, 12, 16 and 20 MeV were used for the calculations. The variation in dose distribution with different energies of abutte electron segments and change in segment size were studied. In order to obtain homogenous dose at the segment match, various gaps and smoothing between segments were introduced. Finally, a salivary gland MERT plan was executed using the segment match optimization scheme. Results: As the energy difference between two consecutive segments increased, dose uniformity at the segment junction decreased. For small segments (< 4 cm) optimization can be improved by introducing a gap (1–2 mm) between segments. However, for larger segments, smoothing was found to be more beneficial than gapping the segments. The salivary gland case was successful in terms of dose coverage and homogeneity aided by the segment matching techniques described. Conclusions: We conclude that use of bigger segments, and smaller differences in energy for abutting segments, should be prioritized for MERT planning. This study provides an optimization regimen of segment matching for MERT treatment planning with gaps/smoothing, depending on segment size and energy in order to provide better dose coverage and expedite the forward planning process. Varian Master Research Agreement
Purpose: To develop novel segmentation software that allows users to segment regions of interest and reconstruct three‐dimensional surfaces using non‐transverse image planes. Method and Materials: To ...date the manual segmentation process in radiation oncology has been performed on consecutive transverse computed tomography (CT) image planes. This method of contouring provides little information about the ends of a structure and is poorly suited for structures whose longitudinal axis lies oblique to the transverse plane. Due to these limitations it has been illustrated that the segmentation of structures using only transverse planes is prone to error and time consuming in nature. We hypothesize that the intelligent selection and use of non‐transverse image planes will reduce observer error and the time burden of the segmentation process. At present few treatment planning systems offer segmentation in non‐transverse planes. The development of this software has four phases: 1) Navigation and segmentation toolsets. 2) Segmentation validation. 3) Curve and vertex processing. 4) Three‐dimensional surface reconstruction. Results: The first and fourth phases are complete. Phases two and three are currently underway with data from a user study illustrating process improvements to be addressed by our software. Our initial results are promising and indicate that it is possible to generate accurate surfaces with a significant reduction in the segmentation burden. Conclusions: The current method of manual structure segmentation is not ideal and represents a significant bottleneck in the treatment planning process. This software promises to improve the accuracy and efficiency of the segmentation process through the use of non‐transverse image planes. While this software was specifically developed to improve the segmentation process, we feel the use of non‐transverse image planes is directly applicable to segmentation and dose distribution review.
Study of τ−→KSπ−ντ decay at Belle Epifanov, D.; Aihara, H.; Aulchenko, V. ...
Physics letters. B,
10/2007, Letnik:
654, Številka:
3-4
Journal Article
Recenzirano
We present a study of the decay τ−→KSπ−ντ using a 351 fb−1 data sample collected with the Belle detector. The analysis is based on 53,110 lepton-tagged signal events. The measured branching fraction ...B(τ−→KSπ−ντ)=(0.404±0.002(stat.)±0.013(syst.))% is consistent with the world average value and has better accuracy. An analysis of the KSπ− invariant mass spectrum reveals contributions from the K∗(892)− as well as other states. For the first time the K∗(892)− mass and width have been measured in τ decay: M(K∗(892)−)=(895.47±0.20(stat.)±0.44(syst.)±0.59(mod.)) MeV/c2, Γ(K∗(892)−)=(46.2±0.6(stat.)±1.0(syst.)±0.7(mod.)) MeV. The K∗(892)− mass is significantly different from the current world average value.
We present measurements of decay amplitudes and triple-product correlations in B{yields}{phi}K* decays based on 253 fb{sup -1} of data recorded at the {upsilon}(4S) resonance with the Belle detector ...at the KEKB e{sup +}e{sup -} storage ring. The decay amplitudes for the three different helicity states are determined from the angular distributions of final-state particles. The longitudinal polarization amplitudes are found to be 0.45{+-}0.05{+-}0.02 for B{sup 0}{yields}{phi}K*{sup 0} and 0.52{+-}0.08{+-}0.03 for B{sup +}{yields}{phi}K*{sup +} decays. CP- and T-odd CP-violating triple-product asymmetries are measured to be consistent with zero.
We report the first measurement of the forward-backward asymmetry and the ratios of Wilson coefficients A{sub 9}/A{sub 7} and A{sub 10}/A{sub 7} in B{yields}K{sup *}l{sup +}l{sup -}, where l ...represents an electron or a muon. We find evidence for the forward-backward asymmetry with a significance of 3.4{sigma}. The results are obtained from a data sample containing 386x10{sup 6} BB pairs that were collected on the {upsilon}(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{sup +}e{sup -} collider.
PDF
