background : in spite of clinically useful photon and electron beams, high energy linacs produce secondary particles such as neutrons (photo-neutron production). neutrons have important roles during treatment with high energy photons in terms of protection and dose escalation. in this project, neutron dose equivalent of 18 mv varian accelerators is calculated by tld600 and tld700. materials and...

Introduction: Paediatric patients deserve special attention because of the higher radiation risks compared with adults. The main purpose of this study is to determine patient dose and diagnostic reference level for Paediatric through Entrance Surface Dose (ESD) calculations in common X-ray examination and to establish Paediatric national DRLs in digital radiography in Iran. <...

background: the trabecular bone changes in the tibia of c3h/hen mice were measured 12 weeks after whole body irradiation with various doses of fast neutrons (0-2.4 gy) or 137cs-generated gamma-rays (0-6 gy). materials and methods: serum calcium, phosphorus, estradiol concentration and alkaline phosphatase activity were measured. tibiae were analyzed using microcomputed tomography. biomechanical...

Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields. An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate two-dimensional map of surface dose if required. Results have shown...

Several instruments have been used to measure absorbed radiation dose under non-electronic equilibrium conditions, such as in the build-up region or near the interface between two different media, including the surface." Many of these detectors are discussed in this paper. A common method of measuring the absorbed dose distribution and electron contamination in the build-up region of high-energ...

background: megavoltage beams used in radiotherapy are contaminated with secondary electrons. different parts of linac head and air above patient act as a source of this contamination. this contamination can increase damage to skin and subcutaneous tissue during radiotherapy.  monte carlo simulation is an accurate method for dose calculation in medical dosimetry and has an important role in opt...

background: the shielding methods in radiotherapy due to delivering an accurate radiation dose to cancer tissues and avoiding unnecessary dose to normal tissues are very important. these methods include lead standard blocks, individual molding and multi leaf collimator (mlc). the mlc method is not still common in iran radiotherapy centers. individual molding is better than the lead block shield...