Coincidence energy spectra due to the intrinsic radioactivity of LYSO scintillation crystals
Por:
Enriquez-Mier-y-Teran, Francisco Eduardo, Ortega-Galindo, Ana Saret, Murrieta-Rodriguez, Tirso, Rodriguez-Villafuerte, Mercedes, Martinez-Davalos, Arnulfo, Alva-Sanchez, Hector
Publicada:
1 ene 2020
Resumen:
Background: Lutetium oxyorthosilicate or lutetium yttrium oxyorthosilicate (LYSO) scintillation crystals used in most current PET scanner detectors contain 176Lu, which decays by beta emission to excited states of 176Hf accompanied by the emission of prompt gamma rays or internal conversion electrons. This intrinsic radioactivity can be self-detected in singles mode as a constant background signal that has an energy spectrum whose structure has been explained previously. In this work, we studied the energy spectrum due to the intrinsic radioactivity of LYSO scintillation crystals of two opposing detectors working in coincidence mode. The investigation included experimental data, Monte Carlo simulations and an analytical model. Results: The structure of the energy spectrum was completely understood and is the result of the self-detection of beta particles from 176Lu in one crystal and the detection of one or more prompt gamma rays detected in coincidence by the opposing crystal. The most probable coincidence detection involves the gamma rays of 202 and 307 keV, which result in two narrow photopeaks, superimposed on a continuous energy distribution due to the beta particle energy deposition. The relative intensities of the gamma ray peaks depend on crystal size and detector separation distance, as is explained by the analytical model and verified through the Monte Carlo simulations and experiments. Conclusions: The analytical model used in this work accurately explains the general features of the coincidence energy spectrum due to the presence of 176Lu in the scintillation crystals, as observed experimentally and with Monte Carlo simulations. This work will be useful to those research studies aimed at using the intrinsic radioactivity of LYSO crystals for transmission scans and detector calibration in coincidence mode. © 2020, The Author(s).
Filiaciones:
Enriquez-Mier-y-Teran, Francisco Eduardo:
Facultad de Ciencias, Universidad Nacional Autónoma de México, México City, 04510, Mexico
Univ Nacl Autonoma Mexico, Fac Ciencias, Mexico City 04510, DF, Mexico
Ortega-Galindo, Ana Saret:
Facultad de Ciencias, Universidad Nacional Autónoma de México, México City, 04510, Mexico
Univ Nacl Autonoma Mexico, Fac Ciencias, Mexico City 04510, DF, Mexico
Murrieta-Rodriguez, Tirso:
Instituto de Física, Universidad Nacional Autónoma de México, A.P. 20-364, Mexico City, 01000, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, AP 20-364, Mexico City 01000, DF, Mexico
Rodriguez-Villafuerte, Mercedes:
Instituto de Física, Universidad Nacional Autónoma de México, A.P. 20-364, Mexico City, 01000, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, AP 20-364, Mexico City 01000, DF, Mexico
Martinez-Davalos, Arnulfo:
Instituto de Física, Universidad Nacional Autónoma de México, A.P. 20-364, Mexico City, 01000, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, AP 20-364, Mexico City 01000, DF, Mexico
Alva-Sanchez, Hector:
Instituto de Física, Universidad Nacional Autónoma de México, A.P. 20-364, Mexico City, 01000, Mexico
Univ Nacl Autonoma Mexico, Inst Fis, AP 20-364, Mexico City 01000, DF, Mexico
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