Tian, P. Chen, Q.S. Fan, K. Li, J.Q. Tang, K. JACoW Publishing Geneva, Switzerland 978-3-95450-201-1 10.18429/JACoW-IBIC2018-WEPC16 English 516-518 WEPC16 radiation proton photon simulation instrumentation Contribution to a conference proceedings 2019 2019-01 https://doi.org/10.18429/JACoW-IBIC2018-WEPC16 http://jacow.org/ibic2018/papers/wepc16.pdf A proton therapy facility based on a superconducting cyclotron is under construction in Huazhong University of Science and Technology (HUST). In order to achieve precise treatment or dose distribution, the beam current would vary from 0.4 nA to 500 nA, in which case conventional non-intercepting instruments would fail due to their low sensitivity. So we propose to use a retractable scintillating screen to measure beam position and beam profile. In this paper, a comprehensive description of our new designed screen monitor is presented, including the choice of material of the screen, optical calibration and simulation of radiation protection. According to the off-line test, the resolution of the screen monitor can reach 0.13 mm/pixel.