The present disclosure provides methods of treating a biological tissue using a proton beam. A method includes the steps of: irradiating a proton beam to a biological tissue containing a reactant. The reactant includes a composite. The composite reacts with at least one proton from the proton beam and releases at least one α particle or γ rays. The α particle or γ rays reacts with the biological tissue. Another method includes the steps of: providing a reactant, the reactant comprising a composite; introducing the reactant into a biological tissue, the reactant being distributed in the biological tissue; and irradiating the biological tissue with the proton beam. The composite reacts with at least one proton from the proton beam to release at least one α particle or γ rays, and the α particle or the γ rays reacts with the biological tissue.