A device and method for radioembolization in the treatment of cancer cells in the body. In preferred embodiments, a radiomicrosphere is formed from a resin where an alpha emitting isotope is used for tumoricidal purposes. As the alpha emitter decays, daughters of the alpha decay are captured by the resin. In further embodiments, the device comprises at least two isotopes； wherein a first isotope is for therapeutic purposes and a second isotope is for dosimetric purposes. The second isotope is a positron emitter for PET based dosimetry. In preferred embodiments, a post-treatment radiation absorbed dose is determined using the present invention, allowing both treatment and treatment efficacy to be provided to a cancer patient.
