نتایج جستجو برای: step and shoot radiation therapy

تعداد نتایج: 17019729  

2008
Douglas A. Swartz Roberto Soria Allyn F. Tennant

A thorough search for Ultraluminous X-ray source candidates within the Local Volume is made. The search spatially matches potential ULXs detected in X-ray images or cataloged in the literature with galaxies tabulated in the Catalog of Neighboring Galaxies compiled by Karachentsev et al. (2004). The specific ULX frequency (occurrence rate per unit galaxy mass) is found to be a decreasing functio...

Journal: :International journal of radiation oncology, biology, physics 2001
W De Gersem F Claus C De Wagter B Van Duyse W De Neve

PURPOSE To describe the theoretical basis, the algorithm, and implementation of a tool that optimizes segment shapes and weights for step-and-shoot intensity-modulated radiation therapy delivered by multileaf collimators. METHODS AND MATERIALS The tool, called SOWAT (Segment Outline and Weight Adapting Tool) is applied to a set of segments, segment weights, and corresponding dose distribution...

2006
Sampo Smolander Pauline Stenberg Elja Arjas Ranga B. Myneni

This work develops methods to account for shoot structure in models of coniferous canopy radiative transfer. Shoot structure, as it varies along the light gradient inside canopy, affects the efficiency of light interception per unit needle area, foliage biomass, or foliage nitrogen. The clumping of needles in the shoot volume also causes a notable amount of multiple scattering of light within c...

Journal: :Tree physiology 2001
P Y Bernier F Raulier P Stenberg C H Ung

We have developed a spatially inexplicit model of canopy photosynthesis for balsam fir (Abies balsamea (L.) Mill.) that accounts for key processes of light-shoot interaction including irradiance interception by the shoot, spatial aggregation of shoots into branches and crowns, the differential propagation of diffuse and direct light within the canopy, and an ideal representation of penumbra. Al...

2005
Sampo Smolander Pauline Stenberg

Simulations of the different components of the spectral radiation budget of structurally simple leaf and shoot canopies with varying canopy leaf area index (LAI) were performed. The aims were (1) to test a proposed parameterization of the budget using two spectrally invariant canopy structural parameters ( p and pt) governing canopy absorption and transmittance, respectively, and (2) to incorpo...

2006
Nelia Mann Samuel E. Vázquez

We present a simple procedure to construct non-local conserved charges for classical open strings on coset spaces. This is done by including suitable reflection matrices on the classical transfer matrix. The reflection matrices must obey certain conditions for the charges to be conserved and in involution. We then study bosonic open strings on AdS5×S. We consider boundary conditions correspondi...

Journal: :iranian journal of radiation research 0
a. kazemian department of radiation oncology, cancer institute, tehran university of medical sciences, tehran, iran h.r. dehghan manshadi m. sardari kermani

sinonasal teratocarcinosarcoma (sntcs) is a rare tumor characterized by mixture architecture of epithelial and mesenchymal components. sntcs is a highly malignant tumor displaying progressive and aggressive growth with poor prognosis. only about 40% of all patients survive after five years. it seems the combination of surgery and radiotherapy currently is the most effective treatment. in this r...

Journal: :Physics in medicine and biology 2013
David Craft Christian Richter

We consider Pareto surface based multi-criteria optimization for step and shoot IMRT planning. By analyzing two navigation algorithms, we show both theoretically and in practice that the number of plans needed to form convex combinations of plans during navigation can be kept small (much less than the theoretical maximum number needed in general, which is equal to the number of objectives for o...

2001
Gary A. Ezzell Suzanne Chungbin

The control loop in the Varian DMLC system (V4.8) requires approximately 65 msec to monitor and halt the irradiation of a segment, causing an "overshoot" effect: the segment ends on a fractional monitor unit larger than that planned. As a result, the actual MU delivered may differ from that planned. In general, for step-and-shoot treatments, the first segment receives more, the last receives le...

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