Energy and air kerma dependence of response of a photodiode-based dosimetric system for radioprotection

Abstract

Low-level X-ray dose measurements are carried out to characterize a portable photodiode-based dosimetric system. In this paper, the energy and air kerma dependence of response is evaluated. The developed system is capable of real-time direct-reading radiation-dose measurement for radioprotection (occupational monitoring) or radiodiagnostic (patient dosimetry). The system can be configured to use various remote portable dosimeters and a computer server for data processing and display. The communication between the portable dosimeter and the server can be carried out in two modes: wireless or USB. The wireless connection is the standard usage mode, and the USB connection is for configuration or testing. The communication protocol is custom-made. For occupational monitoring, ISO 4037–1 was applied, and the following radioprotection qualities were tested: N40, N60, N80, N100, and N120. It was also tested in the following radiodiagnostic qualities: RQR3, RQR5, RQR8, and RQR10, as defined by IEC 61267. Besides X-rays, the developed dosimeter was evaluated for gamma ray energies of Cs-137 and Co-60. It is observed that the dosimeter sensitivity response displays a standard deviation less than 10% within a coefficient of variation of 1% in the reproducibility tests. The system is considered closely linear for air kerma dependence in the radiation qualities investigated. Goodness of fit was evaluated with the reduced chi-squared test.