Linacs equipped with flattening filter-free (FFF) megavoltage photon beams are now commercially available. However, the commissioning of FFF beams poses challenges that are not shared with traditional flattened megavoltage X-ray beams. The planning system must model a beam that is peaked in the center and has an energy spectrum that is softer than the flattened beam. Removing the flattening fil...

This work outlines the development of a robust method of calculating modulation factors used for the independent verification of MUs for IMRT and VMAT treatments, to replace onerous ion chamber measurements. Two-dimensional fluence maps were calculated for dynamic MLC fields that include MLC interleaf leakage, transmission, and tongue-and-groove effects, as characterized from EPID-acquired imag...

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...

A new proposal is given to design a spin half-adder in nano-junction. It well known that at finite voltage net circulating current (known as circular current) appears within mesoscopic ring under asymmetric ring-to-electrode interface configuration. This induces magnetic field the center of ring. We utilize this phenomenon construct half adder. The induced used regulate alignments local free sp...

introduction: in radiotherapy, methods of treatment planning are becoming increasingly more complicated. this requires verification of the doses delivered to increasingly smaller and more precise regions. radiotherapy techniques are continuously employing smaller and smaller field sizes to deliver tighter radiation doses with higher therapeutic ratios, generating interest among researchers to p...

Introduction Magnetic fields are capable of altering the trajectory of electron beams andcan be used in radiation therapy.Theaim of this study was to produce regions with dose enhancement and reduction in the medium. Materials and Methods The NdFeB permanent magnets were arranged on the electron applicator in several configurations. Then, after the passage of the electron beams (9 and 15 MeV Va...

Previous investigators of EPID dosimetric properties have ascribed the backscatter, that contaminates dosimetric EPID images, to its supporting arm. Accordingly, Monte-Carlo (MC) EPID models have approximated the backscatter signal from the layers under the detector and the robotic support arm using either uniform or non-uniform solid water slabs, or through convolutions with back-scatter kerne...

INTRODUCTION The magnitude of intra- and inter-fractional variation in the set up of breast cancer patients treated with tangential megavoltage photon beams was investigated using an electronic portal imaging device (EPID). METHODS Daily cine-EPID images were captured during delivery of the tangential fields for ten breast cancer patients treated in the supine position. Measurements collected...

PURPOSE The aim of this study is to evaluate the ability of transit dosimetry using commercial treatment planning system (TPS) and an electronic portal imaging device (EPID) with simple calibration method to verify the beam delivery based on detection of large errors in treatment room. METHODS AND MATERIALS Twenty four fields of intensity modulated radiotherapy (IMRT) plans were selected from...

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 small fields,...