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Purpose:Carbon-ion therapy can get better dose distribution in comparison with conventional radiotherapy owing to its Bragg Peak.But the beam range verification remained intractable.Positron emission tomography(PET)is potentially a good resolution,especially for in-beam range verification.This method is based on the detection of β+emitted by 11C,15O,10C produced during carbon-ion therapy,thus β+production is important to PET image quality.This study is to calculate the positron emitter production in clinical carbon-ion radiotherapy and give a preliminary result.Methods:For PET imageing during carbon-ion therapy,we use two plate(usually fixed on the gantry)detector heads to avoid the interference with the treatment beamline.The PET head are made of 3*5 detector modules,and each module includes a 25*25 array.For a single array,it consists of a 2mm*2mm*18mm LYSO pixels.A PMMA phantom of 15cm*15cm*15cm was irradiated by a 200 MeV and 250 MeV 12C beamline with 8mm FWHM and 10e6 pps separately.GATE,a monte carlo software based on GEANT4,is used for PET simulation Results:The yield result shows 11C is the most important nuclei contributing to the total positron production,with 9.63%and 12.85%for the simulated beam energy.The production of 10C and 15O are much lower,with about 1.5%in total.As for the simulated beam,we can get larger proportion of positron emitters using higher beam energy.Conclusions:In this study,we simulated a dual-plate PET scanner used in carbon-ion radiotherapy and got the positron emitter yields produced by different beam energy.The result shows the feasibility that PET could be used in carbon-ion radiotherapy for in-beam verification.The future work is to take more detailed analysis using real human phantom.