Singles-prompt: a novel method to estimate random coincidences by using prompts and singles information

Josep F. Oliver; M. Rafecas

doi:10.1117/12.878087

16 March 2011 Singles-prompt: a novel method to estimate random coincidences by using prompts and singles information

Josep F. Oliver, M. Rafecas

Proceedings Volume 7961, Medical Imaging 2011: Physics of Medical Imaging; 796149 (2011) https://doi.org/10.1117/12.878087
Event: SPIE Medical Imaging, 2011, Lake Buena Vista (Orlando), Florida, United States

Abstract

Random coincidences are one of the main sources of image degradation in Positron Emission Tomography (PET) imaging. This aspect becomes especially important when high image quality is needed or accurate quantitative analysis is undertaken. To correct for these degradation effects, an accurate method to estimate the contribution of random events is necessary. A common method of choice is the so called "Singles Rate" method (SR), widely used because of its good statistical properties. SR is based on the measurement of the singles count rate in each detector, R^SR/_ij = 2τS_iS_j. However, the SR method always overestimates the correct randoms rate value, especially for non-extended sources close to the center field of view of the scanner. In this work an extension of the SR method is proposed. The novel method, called "Singles-Prompts" (SP) takes advantage of the extra information provided by the measured prompts. Changing SR by SP is straightforward since only two simple replacements in the SR formula are required. To validate the method, Monte Carlo simulations have been performed. A small animal PET has been used together with three source geometries that cover two limiting cases: from a point-like source to an extended source. The results show that the SP estimation is more accurate than that of SR and always has a smaller variance. More importantly, for energy windows that prevent to register multiple events caused by inter-crystal scatter (ICS), the SP method provides an estimation compatible with the correct value regardless of the geometry of the source.

Citation Download Citation

Josep F. Oliver and M. Rafecas "Singles-prompt: a novel method to estimate random coincidences by using prompts and singles information", Proc. SPIE 7961, Medical Imaging 2011: Physics of Medical Imaging, 796149 (16 March 2011); https://doi.org/10.1117/12.878087

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