The invention comprises a system for determining the state of a charged particle beam, such as beam position, intensity, and/or energy. For example, the charged particle beam state is determined at or about a patient undergoing charged particle cancer therapy using one or more film layers designed to emit photons upon passage of a charged particle beam, which yields information on position and/or intensity of the charged particle beam. The emitted photons are used to calculate position of the treatment beam in imaging and/or during tumor treatment. Optionally and preferably, updating a tomography map uses the same hardware with the same alignment used for cancer therapy at proximately the same time.
