background: absolute dosimetry of external beam radiotherapy is carried out by the use of ionization chambers. these chambers must be calibrated at a standard dosimetry laboratory before any use in clinical dosimetry. the secondary standard dosimetry laboratory of iran (ssdl) has the duty of calibrating the ionization chambers used in radiotherapy centers in iran. materials and methods: the pre...

The practice of using the direct ionization radiation (electrons, protons, antiprotons, pions, ions, etc) or of the indirect ionization radiation (photons, neutrons, etc) in economy and social life has led to the introduction of the absorbed dose magnitude (ICRU 1953) defined as the energy absorbed per mass unit of the irradiated substance. This is a fundamental magnitude valid for any type of ...

background: the monte carlo method is the most accurate method for simulation of radiation therapy equipment. the linear accelerators are currently the most widely used machines in radiation therapy centers. methods: in this work, a monte carlo modelling of the siemens oncor linear accelerator in 6 mv and 18 mv beams was performed. the results of simulation were validated by measurements in wat...

Background: Absolute dosimetry of external beam radiotherapy is carried out by the use of ionization chambers. These chambers must be calibrated at a standard dosimetry laboratory before any use in clinical dosimetry. The secondary standard dosimetry laboratory of Iran (SSDL) has the duty of calibrating the ionization chambers used in radiotherapy centers in Iran. Materials and Methods...

When pulse of electromagnetic radiation impinges upon a moving plasmalneutral gas boundary, i.e., an ionization front, its frequency and duration are altered. The largest frequency upshifts and pulse compressions are obtained when radiation is incident on an ionization front moving at close to the speed of light. Such an ionization front is created when a short laser pulse photo-ionizes a gas t...

We have just concluded the study of radiation interaction with matter in which the basic mechanisms of charged particle, neutron and gamma interactions were discussed separately. A topic which makes use of all this information is the general problem of detection of nuclear radiation detection. Although this subject properly belongs to a course dealing with experimental aspects of applied nuclea...

The non linear interaction between an intense laser radiation and atoms leads to ionization through the absorption of N photons from the laser radiation via laser-induced virtual states. The multiphoton ionization rate varies as a function of the laser intensity I as IN. We discuss the two most important effects which govern multiphoton ionization processes : resonance effects and laser-coheren...

8-Oxoguanine is one of the key products of indirect radiation damage to DNA by reactive oxygen species. Here, we describe ionization of this damaged nucleobase and the corresponding nucleoside and nucleotide in aqueous phase, modeled by the nonequilibrium polarizable continuum model, establishing their lowest vertical ionization energies of 6.8-7.0 eV. We thus confirm that 8-oxoguanine has even...