Variation in dosimeter calibration factor (Ndw) over a period of 20 years

In this study, the NDWfactor for two ion chambers, thimble type (Farmer) and parallel plate type (Markus), used in most of the radiotherapy centers, were retrospectively reviewed for 20 years. The calibration on all occasions except once was carried out at the Secondary Standards Dosimetry Laboratory, Bhabha Atomic Research Centre, Mumbai. The change in the NDWfactor over this period was < ±3%. We, therefore, believe that a dosimeter with no history of repairs showed reasonable stability in the NDWfactor over a long period.

Source: Journal of Medical Physics - August 7, 2021 Category: Physics Authors: Manoj Kumar Semwal Harishchandra Gupta Sakshi Singhal Ashok Kumar Aruna Kaushik Source Type: research