PD ISO/TR 24422:2022 PDF

1   Scope A water phantom is used to ensure the accurate measurement of absorbed dose delivered by a radiation therapy machine as well as standardizing the dose distribution produced by the radiation therapy device. This document describes a detailed procedure for the construction and calibration of a polystyrene phantom and the results of its use in measuring the absorbed dose profile around the mechanical centre of a radiosurgery medical device, the full width at half maximum (FWHM) of the field and the physical penumbra at the mechanical centre , as well as the associated uncertainties. According to IAEA TRS‑483 document, the most common design recommended in Gamma Knife ® system is a hemisphere atop a water filled or compact polystyrene cylinder, and when using a polystyrene phantom, the measurement depth of the absorbed dose to water is reported to be the centre of the hemisphere with the radius of 8 cm. This document mainly describes the procedure for measuring the absorbed dose distribution around the mechanical centre of Gamma Knife ® and obtaining the FWHM and penumbra from it. The developed phantom is made of polystyrene and has a hemispherical shape in accordance with the design suggested in IAEA TRS‑483. This type of phantom is specific and adapted only for the Gamma Knife ® radiosurgery facilities (Perfexion TM and Icon TM models) and does not apply to general dosimetry protocols in radiotherapy facilities that use a small ra...