Individualized elective irradiation of the clinically node-negative neck in definitive radiotherapy for head and neck squamous cell carcinoma

Background:Oral cavity(OC),oropharyngeal(OP),hypopharyngeal(HP),and laryngeal(LA)squamous cell carcinoma(SCC)have a high incidence of regional lymph node metastasis(LNM).Elective irradiation for clinically node-negative neck is routinely administered to treat lymph nodes harboring occult metastasis.However,the optimal elective irradiation schemes are still inconclusive.In this study,we aimed to establish individualized elective irradiation schemes for the ipsilateral and contralateral node-negative neck of these four types of cancer.Methods:From July 2005 to December 2018,793 patients with OC-SCC,464 with OP-SCC,413 with HP-SCC,and 645 with LA-SCC were recruited retrospectively.Based on the actual incidence of LNM and the tumor characteristics,risk factors for contralateral LNM,as well as node level coverage schemes for elective irradiation,were determined using logistic regression analysis.Additionally,we developed a publicly available online tool to facilitate the widespread clinical use of these schemes.Results:For the ipsilateral node-negative neck,elective irradiation at levels Ⅰ-Ⅲ for OC-SCC and levels Ⅱ-Ⅳa for OP-,HP-and LA-SCC are generally recommended.In addition,level Ⅶa should be included in patients with OPSCC.Multivariate analyses revealed that posterior hypopharyngeal wall and post-cricoid region involvement were independently associated with level Ⅶa metastasis in HP-SCC(all P<0.05).For the contralateral node-negative neck,multivariate analyses revealed that ipsilateral N2b2-N3,tumors with body midline involvement,and degree of tumor invasion were the independent factors for contralateral LNM(all P<0.05).In patients who require contralateral neck irradiation,levels Ⅰ-Ⅱ are recommended for OC-SCC,and additional level Ⅲ is recommended for patients with ipsilateral N3 disease.Levels Ⅱ-Ⅲ are recommended for OP-,HP-,and LA-SCC,and additional level Ⅳa is recommended for patients with advanced T or ipsilateralNclassifications.Furthermore,additional level Ⅶa is recommended only for OP-SCC with T4 and ipsilateral N3 disease.Conclusion:Based on our findings,we suggest that individualized and computer-aided elective irradiation schemes could reduce irradiation volumes in OC-,OP-and HP-SCC patients,as compared to current guidelines,and could thus positively impact the patients’quality of life after radiotherapy.

LB-AGR: level-based adaptive geo-routing for underwater sensor network

Underwater sensor network（UWSN） adopts acoustic communication with more energy-consumption and longer propagation-delay, which bring great challenges to protocol design. In this paper, we proposed level-based adaptive geo-routing（LB-AGR） protocol. LB-AGR divides traffics into four categories, and routes different types of traffic in accordance with different decisions. Packets upstream to the sink are forwarded unicast to the best next-hop instead of broadcasting to all neighbor nodes as in present UWSN routing protocols. LB-AGR defines an integrated forwarding factor for each candidate node based on available energy, density, location, and level-difference between neighbor nodes, which is used to determine the best next-hop among multiple qualified candidates. Through simulation experiments, we show the promising performance of LB-AGR.

A RECTANGULAR SHELL ELEMENT FORMULATION WITH A NEW MULTI-RESOLUTION ANALYSIS

A multi-resolution rectangular shell element with membrane-bending based on the Kirchhoff-Love theory is proposed. The multi-resolution analysis （MRA） framework is formulated out of a mutually nesting displacement subspace sequence, whose basis functions are constructed of scaling and shifting on the element domain of basic node shape functions. The basic node shape functions are constructed from shifting to other three quadrants around a specific node of a basic element in one quadrant and joining the corresponding node shape functions of four elements at the specific node. The MRA endows the proposed element with the resolution level （RL） to adjust the element node number, thus modulating structural analysis accuracy accordingly. The node shape functions of Kronecker delta property make the treatment of element boundary condition quite convenient and enable the stiffness matrix and the loading column vectors of the proposed element to be automatically acquired through quadraturing around nodes in RL adjusting. As a result, the traditional 4-node rectangular shell element is a mono-resolution one and also a special case of the proposed element. The accuracy of a structural analysis is actually determined by the RL, not by the mesh. The simplicity and clarity of node shape function formulation with the Kronecker delta property, and the rational MRA enable the proposed element method to be implemented more rationally, easily and efficiently than the conventional mono-resolution rectangular shell element method or other corresponding MRA methods.