the aim of radiation therapy treatment planning is to achieve an optimal balance between delivering a high dose to target volume and a low dose to healthy tissues. in order to refrain any complications resulting from the dose to the surrounding normal organs, the role of treatment plan has been critically evaluated in term of how large the volume or mass of normal tissues exposed in the radiati...

introduction radon is a colorless and tasteless gas which exists in most soils. it is a substance that poses a potential risk for lung cancer in case a person is exposed to high levels over long periods of time. the environmental protection agency (epa) estimates that 90% of lung cancers per year are caused by radon. the aim of this paper is to estimate the absorbed doses of 222rn by mcnpx simu...

introduction bnct is an effective method to destroy brain tumoral cells while sparing the healthy tissues. the recommended flux for epithermal neutrons is 109 n/cm2s, which has the most effectiveness on deep-seated tumors. in this paper, it is indicated that using d-t neutron source and optimizing of beam shaping assembly (bsa) leads to treating brain tumors in a reasonable time where all iaea ...

introduction given the fact that children are more sensitive to radiation, compared to adults, special attention needs to be paid to radiation protection in pediatric radiology. diagnostic reference level (drl) has been defined to be employed as a practical tool for examining the overall performance of a radiological center in terms of patient dose among a series of similar equipments in an are...

background: in radiation therapy, water is the phantom material of choice, both for reference and for relative dosimetry measurements. solid phantoms, however, are more useful for routine measurements because they tend to be more robust and easier to set up than water phantoms. materials and methods: fluka input data cards have been arranged in sequential order. a simple cylindrical geometry wi...

in order to avoid using cytotoxic drugs and to minimize prednisolone side effects in frequent relapsing or steroid-dependent idiopathic nephrotic syndrome, 35 patients, 3 to 15 (mean= 8.1) years of age, were studied. while in remission for at least 6 weeks, the dose of prednisolone was reduced to 0.1-0.37 (mean= 0.23) mg/kg/day as a single dose for 12 to 72 (mean= 27.6) months. it was followed ...

background: the purpose of this paper is to establish an easy and reliable biodosimeter protocol to evaluate the biological effects of proton beams. materials and methods: human peripheral blood lymphocytes were irradiated using proton beams (let: 34.6 kev μm−1), and the chromosome aberrations induced were analyzed using cytokinesis-blocked (cb) micronucleus (mn) assay. to determine the efficie...

background: the existence of some radionuclides in soil and some building materials produce a β-γ radiation field, which in some regions the exposure of these radionuclides to human is high. materials and methods: the air-absorbed dose, indoor and outdoor annual effective dose of soil and some building material samples (ceramic, granite, gypsum, etc.). the samples were collected from 35 differe...

background: palliative whole brain radiotherapy (wbrt) has been the standard treatment for brain metastases. ionizing radiation is known to be one of the most potent cataractogenic agents. we aimed to evaluate two different radiotherapy techniques with respect to the doses received by the organs at risk (oar) in patients with brain metastasis who undergone wbrt. materials and methods: ten conse...

background: patient radiation doses from computed tomography (ct) are increasing due to the number of ct examinations performed every day. the aim of this study was assess and evaluate patient radiation doses for adult’s common ct examinations to derive local diagnostic guidance levels for common ct examinations. materials and methods: volume and weighted computed tomography dose index (ctdivol...