Fabrication and validation of a new device for measuring the radiation dose in ethanol-chlorobenzene dosimeters based...

This paper presents a novel digital instrument designed for measuring radiation doses in Ethanol-Chlorobenzene (ECB) dosimeters, based on oscillometry method. ECB dosimeters are versatile tools for radiation measurement, particularly in medical and industrial applications. Various components of the device including measuring cell, analog and digital circuits were designed, simulated, optimized and verified. The measuring cell was manufactured to maximize the sensitivity in detecting changes in the conductivity of the ECB solution inside the ampoules. The analog oscillating circuit was fabricated using new and common elements in the market such as operational amplifiers (Op Amps), diodes and transistors. The oscillator frequency was set to the lowest possible value to reduce the adverse effects of high frequencies. However, further decrease in frequency causes the conductivity changes of the ECB solution to be measured by the analog circuit inefficiently. The digital circuit was designed and constructed to interface with the analog circuit, processing its output voltage. This digital circuit included an ATmega8A microcontroller, a DS18B20 temperature sensor, a graphic LCD, and other widely used integrated circuits (ICs). The overall performance of the apparatus was validated by reading the absorbed dose of a set of dosimeters irradiated at doses of 1, 5, 10, 30, 70, and 100 kGy in the Gamma cell GC-220 of our laboratory. The maximum absolute relative difference between the average dosimeter readouts and expected values was about 7% and the average value of the absolute relative differences at different doses was about 3.3%. The negligible discrepancy between the values read by the manufactured device and the actual values demonstrates the accuracy of the device operation. Therefore, this device can be considered as an appropriate apparatus for reading the ECB dosimeters and can serve as a key component of an ECB dosimetry system for high-dose dosimetry applications.