نتایج جستجو برای: photon

تعداد نتایج: 70717  

Journal: :iranian journal of medical physics 0
m. t. bahreyni toosi professor, medical physics research center, bu-ali research institute, mashhad university of medical sciences, mashhad, iran. m. momen nezhad ph.d. student in medical physics, mashhad university of medical sciences, mashhad, iran h. saberi ph.d. student in medical physics, mashhad university of medical sciences, mashhad, iran m. h. bahreyni toosi professor, medical physics research center, bu-ali research institute, mashhad university of medical sciences, mashhad, iran. a. hashemian assistant professor, medical physics research center, bu-ali research institute, mashhad university of medical sciences, mashhad, iran. r. salek assistant professor, radiation oncology dept., imam reza hospital, mashhad university of medical sciences, mashhad, iran.

ntroduction:  monte  carlo  simulation  is  the  most  accurate  method  of  simulating  radiation  transport  and  predicting doses at different points of interest in radiotherapy. a great advantage of the monte carlo method  compared  to  the  deterministic  methods  is  the  ability  to  deal  accurately  with  any  complex  geometry.  its  disadvantage is the extremely long computing time r...

Journal: :iranian journal of radiation research 0
gh. geraily department of medical physics, tehran university of medical science, tehran, iran m. mirzapour department of electronic, east tehran branch, islamic azad university, tehran, iran s.r. mahdavi department of medical physics, tehran university of medical science, tehran, iran m. allahverdi department of medical physics, tehran university of medical science, tehran, iran a. mostaar department of biomedical engineering and medical physics, shahid beheshti university of medical science, tehran, iran m. masoudifar department of radiation oncology, mahak hospital, tehran, iran

background: physical wedges are still widely used as beam modifiers in external beam radiotherapy. however the presence of them in the beam trace may cause beam hardening which may not be considered in many treatment planning systems. the aim of this study is to investigate the beam hardening effect generated by physical wedges via different beam quality indexes as photon spectrum, half value l...

2000
Markus H. Thoma

Using the effective Lagrangian for the low energy photon-photon interaction the lowest order photon self energy at finite temperature and in nonequilibrium is calculated within the real time formalism. The Debye mass, the dispersion relation, the dielectric tensor, and the velocity of light following from the photon self energy are discussed. As an application we consider the interaction of pho...

Journal: :journal of medical signals and sensors 0
keyvan jabbari somayeh senobari mahnaz roayaei masoumeh rostampour

the cancer of oral cavity is related to lesions of mucous membrane of tongue and gum that can be treated with radiation therapy. a lateral photon field can be used to treat this kind of tumor, which has a side‑effect on normal tissue in the opposite side of the oral cavity. in this study the dosimetric effect of the various shields in oral cavity is evaluated. in this study, a special phantom s...

Journal: :journal of lasers in medical sciences 0
maryam afsari golshan sharif university of technology, tehran, iran maryam ghasemi tarei sharif university of technology, tehran, iran ahmad amjadi sharif university of technology, tehran, iran

introduction : due to the importance of laser light penetration and propagation in biological tissues, many researchers have proposed several numerical methods such as monte carlo, finite element and green function methods. among them, the monte carlo method is an accurate method which can be applied for different tissues. however, because of its statistical nature, monte carlo simulation requi...

Journal: :journal of biomedical physics and engineering 0
s. chatterjee indian institute of astrophysics, bangalore 560034, india a. vyas indian institute of astrophysics, bangalore 560034, india r. ravanfar haghighi medical physics unit, all india institute of medical sciences, ansari nagar, new delhi 110029 india p. kumar medical physics unit, all india institute of medical sciences, ansari nagar, new delhi 110029 india

introduction: the photoelectric attenuation coefficient of substances is known to depend upon the energy e of the photon and the effective atomic number of substances (zeff) as (zeff x /e y ).  no definitive values about these indices x, y are given in the literature. the index x is said to lie between, 3.0 and 4.0, while for ‘y’ different values have been assigned, between 3.0 and 4.0. methodo...

Journal: :iranian journal of radiation research 0
i. akkurt suleyman demirel university science faculty physics department, isparta, turkey h. canakci gaziantep university engineering faculty civil engine department, bol. gaziantep, turkey

background: radiation shielding properties is an important for a material wish can be used the photon attenuation coefficients of clay produced using different rate of boron have been measured for the purpose of radioactive waste disposal. materials and methods: the measurement has been performed using gamma spectrometer contains nai (tl) detector at the photon energies of 662, 1173 and 1332 ke...

Background and purpose: Breast‑conserving surgery followed by radiation therapy to the whole breast is now recognized as a standard strategy in patients with breast cancer. Recommended technique for radiotherapy is whole breast irradiation followed by boost to the tumor bed. This study aimed to compare the dosimetric parameters of electron and photon beams for boosting irradia­tion in post‑lump...

A. Mostaar, Gh. Geraily, M. Allahverdi, M. Masoudifar, M. Mirzapour, S.R. Mahdavi,

Background: Physical wedges are still widely used as beam modifiers in external beam radiotherapy. However the presence of them in the beam trace may cause beam hardening which may not be considered in many treatment planning systems. The aim of this study is to investigate the beam hardening effect generated by physical wedges via different beam quality indexes as photon spectrum, half value l...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید