نتایج جستجو برای: heterogeneous phantom

تعداد نتایج: 142666  

Background: The purpose of this study is to fabricate inexpensive in-house low cost homogeneous and heterogeneous human equivalent thorax phantom and assess the dose accuracy of the Treatment Planning Systems (TPS) calculated values for different lung treatment dosimetery. It is compared with Thermoluminescent Dosimeter (TLD) measurement. Materials and Methods: Homogeneous and heterogeneous tho...

Journal: :Journal of biomedical optics 2012
Juan Felipe Perez-Juste Abascal Juan Aguirre Judit Chamorro-Servent Martin Schweiger Simon Arridge Jorge Ripoll Juan J Vaquero Manuel Desco

Reconstruction algorithms for imaging fluorescence in near infrared ranges usually normalize fluorescence light with respect to excitation light. Using this approach, we investigated the influence of absorption and scattering heterogeneities on quantification accuracy when assuming a homogeneous model and explored possible reconstruction improvements by using a heterogeneous model. To do so, we...

2016
Byung Do Park Tae Gyu Kim Jong Eon Kim

Intensity-modulated radiation therapy (IMRT) provides the protection of the normal organs and a precise treatment plan through its optimization process. However, the final dose-volume histogram (DVH) obtained by this technique differs from the optimal DVH, owing to optimization convergence errors. Herein, intermediate dose calculation was applied to IMRT plans during the optimization process to...

2017
Om Prakash Gurjar Radha Kishan Paliwal Surendra Prasad Mishra

The aim is to study the density, isodose depths, and doses at different points in slab-pinewood-slab (SPS) phantom, solid phantom SP34 (made up of polystyrene), and chest level of actual patient for developing heterogeneous chest phantom mimicking thoracic region of human body. A 6 MV photon beam of field size of 10 cm × 10 cm was directed perpendicular to the surface of computed tomography (CT...

2000
Tatsuto Kimura Shigeo Maruyama

The heterogeneous nucleation of liquid droplet on a solid surface was simulated with the molecular dynamics method. Argon vapor was represented by 5760 Lennard-Jones molecules and the solid surface was represented by one layer of 1020 harmonic molecules with the constant temperature heat bath model using the phantom molecules. The potential parameter between solid molecule and vapor molecule wa...

2000
Tatsuto Kimura Shigeo Maruyama S. MARUYAMA

Heterogeneous nucleation of a liquid droplet on a solid surface was simulated with the molecular dynamics method. Argon vapor was represented by 5,760 Lennard-Jones molecules and the solid surface was represented by one layer of 4,464 harmonic molecules with the constant temperature heat bath model using the phantom molecules. The potential parameter between a solid molecule and a vapor molecul...

Journal: :iranian journal of radiation research 0
a. mostaar medical physics department, tehran university of medical sciences, tehran, iran m. allahverdi department of radiotherapy physics, cancer institute, tehran, iran m. shahriari gamma irradiation center, atomic energy organization of iran, tehran, iran

background: in treating patients with radiation, the degree of accuracy for the delivery of tumor dose is recommended to be within ± 5% by icru in report 24. the experimental studies have shown that the presence of low-density inhomogeneity in areas such as the lung can lead to a greater than 30% change in the water dose data. therefore, inhomogeneity corrections should be used in treatment pla...

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