The invention comprises an apparatus and method of use thereof for determining a charged particle beam state after passage through a final beam modification insert and prior to entering a patient, such as in cancer treatment or tomographic imaging. The insert comprises a range shifter, a known energy absorber, a ridge filter, a focal length altering insert, an aperture defining element, a compensator, and/or a patient specific beam modifier. The monitoring element comprises one or more sheets, configured to emit photons upon passage therethrough of the charged particle beam, where the emitted photons are detected, tested, such as against a predetermined cancer treatment plan, and/or used to aid in three dimensional tomographic image generation.