A new precision measurement of the branching ratio of the rare pion decay into a positron and a neutrino Or-* ev) has been completed. A beam of positive pions was stopped in an active target of plastic scintillator surrounded by a An BGO calorimeter. 3xl0 5 rare decays and 1.2xl0 6 normal pion decays (/r-*/xv) were recorded. The branching ratio was finally calculated from 1.2 xlO 5 rare decays after various cuts in the time window from 7.5 to 200 ns after pion stop. The errors of the result (1.235 ±0.005) x 10 " 4 are 0.28% statistical and 0.29% systematical.PACS numbers: 13.20.Cz An experiment was performed to measure the branching ratio R for the rare decay /r-> ev(y) (i.e., K-+ ev including K-* evy), normalized to the normal pion decay K-* jnv(y) with high precision, testing the fie universality of the weak interaction. This rare decay has been treated theoretically many times and values for R have been published by several authors during the development of the theory of the weak interaction [1-3] and also later inthe framework of gauge theories. The most recent predictions for R are as follows: Marciano and Sirlin [4], (1.233 ±0.004) x 10 " 4 ; Goldman and Wilson [5], (1.239 ± 0.001) x 10 " 4 ; Marciano [6], (1.2345 ± 0.0010) x 10 " 4 .
DTRT plans for different treatment sites were generated and compared with VMAT plans. The delivery is suitable and dose comparisons demonstrate a high potential of DTRT to reduce dose to OARs using less dynamic trajectories than arcs, while target coverage is preserved.
The aim of this work is to develop and investigate an inverse treatment planning process (TPP) for mixed beam radiotherapy (MBRT) capable of performing simultaneous optimization of photon and electron apertures. A simulated annealing based direct aperture optimization (DAO) is implemented to perform simultaneous optimization of photon and electron apertures, both shaped with the photon multileaf collimator (pMLC). Validated beam models are used as input for Monte Carlo dose calculations. Consideration of photon pMLC transmission during DAO and a weight re-optimization of the apertures after deliverable dose calculation are utilized to efficiently reduce the differences between optimized and deliverable dose distributions. The TPP for MBRT is evaluated for an academic situation with a superficial and an enlarged PTV in the depth, a left chest wall case including the internal mammary chain and a squamous cell carcinoma case. Deliverable dose distributions of MBRT plans are compared to those of modulated electron radiotherapy (MERT), photon IMRT and if available to those of clinical VMAT plans. The generated MBRT plans dosimetrically outperform the MERT, photon IMRT and VMAT plans for all investigated situations. For the clinical cases of the left chest wall and the squamous cell carcinoma, the MBRT plans cover the PTV similarly or more homogeneously than the VMAT plans, while OARs are spared considerably better with average reductions of the mean dose to parallel OARs and D to serial OARs by 54% and 26%, respectively. Moreover, the low dose bath expressed as V to normal tissue is substantially reduced by up to 45% compared to the VMAT plans. A TPP for MBRT including simultaneous optimization is successfully implemented and the dosimetric superiority of MBRT plans over MERT, photon IMRT and VMAT plans is demonstrated for academic and clinical situations including superficial targets with and without deep-seated part.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.