Introduction: Due to its simplicity, fast response and high reliability, ion chamber detectors are one of the most suitable dosimetry instruments for X and gamma rays. The dosimeter    of photon beams, which used in radiotherapy centers, requires high accuracy and should pass requirements of IEC 60731 standards. About 80 percent of the IEC 60731 standard tests such as stabil...

-Two parallel-plate ionization chambers were projected, constructed and evauated for use in high energy electron beams. They were constructed using the two plastic materials recommended for clinical dosimetry protocols, i.e. acrylic and polystyrene. Both chambers have cylindrical shape with entrance windows in aluminized Mylar and they are open to the air. The acrylic chamber has a 2 mm air gap...

The Keithley model 602 electrometer-Farmer ionization chamber combination has served as the standard dosimetry system for calibration measurements made by the AAPM Radiological Physics Center at 156 different institutions. The constancy of this system is compared to that for the Baldwin-Farmer Secondary Standard Dosemeter type 2502, and is based on measurements made over a 3-yr period on a Coba...

background: hydrogen peroxide (h2o2), produced by gamma ray irradiation to watery solution, was used as an analytical parameter for dosimetry of cobalt-60 (60co) radiation. materials and methods: detection of the produced h2o2 was carried out using two methods: an amperometric biosensor fabricated by immobilization of anthraquinone 2-carboxylic acid modified horseradish peroxidase on glassy car...

PURPOSE To provide a comprehensive investigation of electron beam reference dosimetry using Monte Carlo simulations of the response of 10 plane-parallel and 18 cylindrical ion chamber types. Specific emphasis is placed on the determination of the optimal shift of the chambers' effective point of measurement (EPOM) and beam quality conversion factors. METHODS The EGSnrc system is used for calc...

Background: Hydrogen peroxide (H2O2), produced by gamma ray irradiation to watery solution, was used as an analytical parameter for dosimetry of cobalt-60 (60Co) radiation. Materials and Methods: Detection of the produced H2O2 was carried out using two methods: an amperometric biosensor fabricated by immobilization of anthraquinone 2-carboxylic acid modified horseradish peroxidase on glassy car...

PURPOSE Ion chamber dosimetry is being used to calibrate dose for cell irradiations designed to investigate photoactivated Auger electron therapy at the Louisiana State University Center for Advanced Microstructures and Devices (CAMD) synchrotron facility. This study performed a dosimetry intercomparison for synchrotron-produced monochromatic x-ray beams at 25 and 35 keV. Ion chamber depth-dose...

Absorbed dose to water in a cobalt-60 gamma-ray beam has been determined using a thick-walled graphite ionization chamber. The chamber was calibrated in a graphite phantom against a graphite calorimeter, and the graphite calibration factor was converted to a water calibration factor using published energy absorption coefficient ratios and a measured replacement factor. Comparisons between the g...

The purpose of this study was to compare dose measurements using ion chamber and radiochromic film dosimetry for a 35-keV synchrotron beam useful for Auger electron therapy. A 1.3-GeV electron beam, transported through a 3-pole superconducting wiggler magnet, produced a polychromatic photon beam from which a 35-keV beam (3.3 mm Al HVL) was selected using a monochromator. A 2.8 cm x 2.5 cm field...

normal 0 false false false en-us x-none fa introduction: in radiation therapy centers across iran, protection of normal tissues is usually accomplished by either cerrobend or lead block shielding. in this study, the influence of these two shielding methods on central axis dose distribution of photon beam a cobalt unit was investigated in clinical conditions. materials and methods: all measureme...