Background and Purpose: After the accident at the Fukushima Daiichi Nuclear Power Station in 2011, detection of radioactive isotopes that were scattered in the atmosphere at that time has become necessary. Furthermore, the shortage of energy resources due to the current conflict between Ukraine and Russia has made it difficult for the EU and Japan to secure electricity. The use of nuclear power plants and detection of the levels of radioactivity are important issues. The aim of this research was to build a system that can easily detect low radioactivity associated with nuclear power. <br>Materials and Methods: To detect low radiation, a coin was placed on a dental imaging plate and a container containing radioactive cesium-contaminated soil was placed on top of it. After a period of exposure （1-30 days）, we detected radioactivity and assessed radiation protection. Using a standard sample （surface dose rate of 0.44μSv）, the detection period with and without post-irradiation X-ray were compared. The relationship between the detection period and the total dose was evaluated by varying the amount of radioactivity. <br>Result: The detection period for a standard sample without post-irradiation X-ray was about 25 to 30 days. Post-irradiation shortened the detection period to 40 hours （approximately 1/15 of the standard detection period）. As the amount of radioactivity increased, the detection period became shorter, but the total exposure dose remained unchanged at 14.4-18.7μSv; furthermore, detection of very low doses was possible. <br>Conclusion: Very low doses of radioactive cesium were detected by the method of post X-ray irradiation to dental imaging plate after exposure to radioactivity. Dental clinics may be useful in the implementation of a large-scale radioactivity detection system.