نتایج جستجو برای: heterogeneous phantom

تعداد نتایج: 142666  

Journal: :CoRR 2016
Mahdi Ajamgard Hamid Shahrokh Shahraki

Vastly increasing capacity and coverage demand in communication networks accompanied by energy efficiency challenge is getting attraction in research topics of this area. In this paper, an improved structure of Phantom cell heterogeneous networks (HetNets) is proposed to fulfil these requirements in the next generation cellular networks.It will be shown that the proposed orthogonal frequency-di...

2012
Tayeb Allahverdi Pourfallah Mahmoud Allahverdi Mohammad Hasan Zahmatkesh

Introduction Polymer gel dosimeters offer a practical solution to 3D dose verification for conventional radiotherapy as well as intensity-modulated and stereotactic radiotherapy. In this study, EGSnrc calculated and PAGAT polymer gel dosimeter measured dose profiles from single shot irradiation with 18 mm collimator of Gamma Knife in homogeneous and inhomogeneous phantoms were compared with eac...

2017
Weixin Si Xiangyun Liao Qiong Wang Pheng Ann Heng

BACKGROUND Biomechanical deformable volumetric registration can help improve safety of surgical interventions by ensuring the operations are extremely precise. However, this technique has been limited by the accuracy and the computational efficiency of patient-specific modeling. METHODS This study presents a tissue-tissue coupling strategy based on penalty method to model the heterogeneous be...

2002
Kent A. Gifford David S. Followill H. Helen Liu George Starkschall

An extensive set of measured data was developed for the purpose of verifying the accuracy of a photon dose-calculation algorithm. Dose distributions from a linear accelerator were measured using an ion chamber in a water phantom and thermoluminescent dosimeters in a heterogeneous anthropomorphic phantom. Test cases included square fields, rectangular fields, fields having different source-to-su...

2013
Martin Maas Eric Love Emil Stefanov Mohit Tiwari Elaine Shi Krste Asanović John Kubiatowicz Dawn Song

In recent work published at ACM CCS 2013 [5], we introduced Phantom, a new secure processor that obfuscates its memory access trace. To an adversary who can observe the processor’s output pins, all memory access traces are computationally indistinguishable (a property known as obliviousness). We achieve obliviousness through a cryptographic construct known as Oblivious RAM or ORAM. Existing ORA...

Journal: :Measurement science & technology 2013
James A Guggenheim Hector R A Basevi Jon Frampton Iain B Styles Hamid Dehghani

A multi-modal optical imaging system for quantitative 3D bioluminescence and functional diffuse imaging is presented, which has no moving parts and uses mirrors to provide multi-view tomographic data for image reconstruction. It is demonstrated that through the use of trans-illuminated spectral near infrared measurements and spectrally constrained tomographic reconstruction, recovered concentra...

Journal: :iranian journal of radiation research 0
a. takavar department of medical physics, tehran university of medical sciences,tehran, iran gh. shamsipour m. sohrabi m. eftekhari

background: in myocardial perfusion spect imaging, images are degraded by photon attenuation, the distance-dependent collimator, detector response and photons scatter. filters greatly affect quality of nuclear medicine images materials and methods: a phantom simulating heart left ventricle was built. about 1mci of 99mtc was injected into the phantom. images were taken from this phantom. some fi...

Journal: :Medical physics 2006
Ann Van Esch Laura Tillikainen Jukka Pyykkonen Mikko Tenhunen Hannu Helminen Sami Siljamäki Jyrki Alakuijala Marta Paiusco Mauro Iori Dominique P Huyskens

The analytical anisotropic algorithm (AAA) was implemented in the Eclipse (Varian Medical Systems) treatment planning system to replace the single pencil beam (SPB) algorithm for the calculation of dose distributions for photon beams. AAA was developed to improve the dose calculation accuracy, especially in heterogeneous media. The total dose deposition is calculated as the superposition of the...

Journal: :Transactions of the American Mathematical Society 2007

Journal: :Cancer biotherapy & radiopharmaceuticals 2016
Maryam Khazaee Moghadam Alireza Kamali Asl Parham Geramifar Habib Zaidi

PURPOSE The aim of this work is to evaluate the application of tissue-specific dose kernels instead of water dose kernels to improve the accuracy of patient-specific dosimetry by taking tissue heterogeneities into consideration. MATERIALS AND METHODS Tissue-specific dose point kernels (DPKs) and dose voxel kernels (DVKs) for yttrium-90 (90Y), lutetium-177 (177Lu), and phosphorus-32 (32P) are ...

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