Introduction:There are various low-level radioactive contamination areas in some part of eastern Japan and RI facilities.Radiation exposure from gamma-rays emitted in these contamination areas is one of the social problems in the world.If the radiation sources are visualized in advance,it is possible to decrease the amount of radiation exposure.In this study,we have developed a novel low-cost gamma-ray imaging Compton camera that has a high detection efficiency and is possible to visualize the gamma-ray sources over the all sky direction.Methods:The detector consisted of eleven CsI(Tl)scintillator cubes with a size of 3.5 cm,each of which readout by super-bialkali photomultiplier tubes.We adopted the flash ADC board operated at 2.5 MHz with SiTCP technology which was developed by KEK Open-It project.The SiTCP is a technology used to connect a front-end to a PC via Ethernet,and it is usually implemented with field programmable gate arrays(FPGA).Online program was made with Visual C++language and ROOT library.Image reconstruction was done by accumulating rings with the radius of θ degree which was calculated for each event.Result and Discussion:We conducted an experiment in the laboratory.We successfully reconstructed 22Na(0.33 MBq,100 cm)in all sky direction.The angular resolution was found to be 18 degree after using an image-sharpening technique.By using the developed system,we have done the field trials in Fukushima and in the National Cancer Center hospital East in Japan,the results of which will be shown in this conference in detail.Conclusion:We developed the all sky RI imaging monitor.This monitor is able to visualize the gamma-ray source over the all sky direction.The experimental results show that our proposed detector would be suitable for a low-level radioactive contamination monitor.