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Android App for Converting Smartphone to Individually Calibrated Dosimeter

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A Sebastin

J Joseph, A Sebastin*, W Michael Raj, PB Ravindran, RR Singh, Christian Medical College, Vellore, India


SU-I-GPD-T-633 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: CCD (Charged coupled Device) or CMOS (Complementary metal-oxide-semiconductor), used as camera sensors, also detects ionising radiation. The objective of the study is to develop an android application to convert a smartphone into individually calibrated dosimeter. We would also like to study its characteristics such as dose-rate response, consistency, energy response, etc.

Methods: When a CCD/CMOS is exposed to ionising radiation (X/Gamma rays), specks proportional to the number of incident photons will be formed on the frame. By counting the number of specks formed, radiation can be quantified and then calibrated.To achieve this, we developed an android app that includes algorithms for:(1)Calibration - to determine the threshold pixel value above which the pixel is to be considered as a radiation signal.(2)Noise filtration - by high-delta method which will also help in determining the signal from each frame.Dose-rate Response: Using a brachytherapy unit (gamma source – 192Ir), the response of a smartphone camera was studied and compared with the theoretical exposure rate at various distances.Energy Response: Images were captured at various energies (40 kV, 60 kV, 80kV) and the sum of pixel values in each image were observed.The smartphone readings are compared with a standard dosimeter and cross-calibrated to standard units.

Results: From the algorithms implemented, the app gave raw data sums to be calibrated to doses. The linear plot obtained between these sums measured at various distances and the inverse of square-of-distances shows a linear dose-rate response.The smartphone is found to have linear energy response as the sum of the pixels in images captured at various energies of X-rays varied linearly with the energy.

Conclusion: Though smartphones have already been shown to be good radiation detectors, an effective individual calibration algorithm for each device can make them comparable to standard detectors.

Funding Support, Disclosures, and Conflict of Interest: Fluid Research Funding, Institutional Review Board, Christian Medical College, Vellore

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