Background: Radiosurgery is a focal brain irradiation technique that delivers, usually in a single session, high dose of ionizing radiation. The presence of lateral electronic disequilibrium and steep dose gradients in small fields demands special attention to the selection of a suitable detector with respect to its size, composition and response. Materials and Methods : Small circular fields w...

introduction: using beta emitter radionuclide is a useful therapeutic modality in the treatment of skin cancers in areas which are difficult to cure by other methods. the aim of this research is to evaluate the tissue response to beta rays of 166ho and determine the feasibility of beta emitting radionuclide for treatment of skin cancers. methods: in this work, we have calculated depth dose dist...

Background: Prediction of the absorbed dose in irradiated volume plays an important role in the outcome of radiotherapy. Application of small fields for radiotherapy of thorax makes the dose calculation process inaccurate due to the existence of electronic disequilibrium and intrinsic deficiencies in dose calculation algorithms. To study the lung absorbed dose in radiotherapy with smal...

Background: The aim of this work was to establish how well gel dosimeters performed, as substitutes for brain tissue compared with standard phantom materials such as water, polymethyl-methacrylate (or PMMA), A150 plastic and TE- liquid phantom material for dosimetry of neutron beams in boron neutron capture therapy. Materials and Methods: Thermal neutron fluence, photon dose and epithermal neu...

  Introduction: Using beta emitter radionuclide is a useful therapeutic modality in the treatment of skin cancers in areas which are difficult to cure by other methods. The aim of this research is to evaluate the tissue response to beta rays of 166Ho and determine the feasibility of beta emitting radionuclide for treatment of skin cancers. Methods: In this...

introduction: skin dose and depth dose distribution of some beta sources that can contaminate skin or protective clothing covering the skin have been calculated using varskin2. materials and methods: in this research, absorbed dose to skin and depth dose from the skin surface have been calculated for 90sr/90y, 147pm, 32p beta emitter radioisotopes by using input parameters: activity of source, ...

background: use of contrast agents (cas) during ct simulation for treatment planing system leads to changes in  electron density. in this study we aimed to investigate the effect on  calculated dose of various concentrations of cas on treatment planing systems in different dose calculation algorithms. materials and methods: contrast agent (0.769 mg/ml iopromid) - water mixtures at concentration...

In the present work, we investigated the accuracy of the electron pencil-beam redefinition algorithm (PBRA) in calculating central-axis percent depth dose in water for rectangular fields. The PBRA energy correction factor C(E) was determined so that PBRA-calculated percent depth dose best matched the percent depth dose measured in water. The hypothesis tested was that a method can be implemente...

Introduction: In recent decades, several Monte Carlo codes have been introduced for research and medical applications. These methods provide both accurate and detailed calculation of particle transport from linear accelerators. The main drawback of Monte Carlo techniques is the extremely long computing time that is required in order to obtain a dose distribution with good statistical accuracy. ...