Amplification of Radiation-Induced Signal of LED Strip by Increasing Number of LED Chips and Using Amplifier Board

Abstract

Transducers, such as photodiodes, phototransistors, and photovoltaic cells are promising radiation detectors. However, for accurate radiation detection and dosimetry, signals that emanate from these devices have to be sufficient to facilitate accurate calibrations, i.e., assigning a quantity of radiation dose to a specific magnitude of the signal. More so, purposely fabricated for luminescence, LEDs produce significantly low signals during radiation detection applications. Therefore, this paper investigates the enhancement and augmentation of photovoltaic signals that were generated when LED strips were being exposed to diagnostic X-rays. Initially, signal amplification was achieved through increasing the effective LED active area (from 60 to 120 chips); by successively connecting LED strips. Further, signal amplification was undertaken by injecting the raw LED strip signal into an amplifier board with adjustable gains. In both the signal amplification techniques, the tube voltage (kVp), tube current-time product (mAs), and source-to-detector distance (SDD) were varied. The principal findings show that effective active area-based signal amplifications produced an overall average of 91.16% signal enhancement throughout all of the X-ray parameter variations. On the other hand, the amplifier board produced an average of 36.48% signal enhancement for the signals that were injected into it. Chip number increment-based signal amplifications had a 0.687% less coefficient of variation than amplifier board signal amplifications. The amplifier board signal amplifications were impaired by factors, such as dark currents, amplifier board maximum operational output voltage, and saturation. Therefore, future electronic signal amplification could use amplifier boards having low dark currents and high operational voltage headroom. The low-cost and simplicity that are associated with active-area amplification could be further exploited in a hybrid amplification technique with electronic amplification and scintillators.