Comparison of Current–Voltage Response to Diagnostic X-rays of Five Light-Emitting Diode Strips

• Main Authors: Edrine Damulira, Muhammad Nur Salihin Yusoff, Suharti Sulaiman, Nur Farah Huda Zulkafli, Nur Amiela Zulkifli, Nur Shahirah Ahmad Shakir, Mohamad Azlan Zainun, Ahmad Fairuz Omar, Nur Hartini Mohd Taib, Nik kamarullah Ya Ali
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Applied Sciences
• Subjects: photonic device; led strip; c–v response; diagnostic x-rays; radiation-induced signal; application of leds
• Online Access: https://www.mdpi.com/2076-3417/10/1/200

Light-emitting diodes (LEDs) have miscellaneous applications owing to their low cost, small size, flexibility, and commercial availability. Furthermore, LEDs have dual applicability as light emitters and detectors. This study explores the current–voltage (C–V) response of LED strips exposed to diagnostic x-rays. Cold white, warm white, red, green, and blue LED strip colors were tested. Each strip consisted of 12 LED chips and was connected to a multimeter. The variable diagnostic x-ray parameters evaluated were kilovoltage peak (kVp), milliampere-seconds (mAs), and source-to-image distance (SID). The radiation dose was also measured using a dosimeter simultaneously exposed to x-rays perpendicularly incident on the strips. Lastly, the consistency of C–V responses, and any possible degradation after 1–2 months was also analyzed. Each LED strip color was ranked according to its C–V response in each of the investigated parameters. The LED strip color with the best cumulative rank across all the tested parameters was then examined for reproducibility. Our findings revealed that the C–V responses of LED strips are (a) generally low but measurable, (b) inconsistent and fluctuating as a consequence of kVp variations, (c) positively correlated to mAs, (d) negatively correlated to SID, and (e) positively correlated to dose. Overall results suggested cold white LED strip as most feasible for x-ray detection—in comparison to examined colors. Additionally, the reproducibility study using the cold white LED strip found a similar trend of C–V response to all variables except kVp. Outcomes indicate that LED strips have the potential to be exploited for detecting low dose (~0–100 mGy) diagnostic x-rays. However, future studies should be carried out to increase the low C–V signal.