What additional particles are produced as a result of the interaction of the beam with patient tissues and accelerator components?

When a therapeutic beam, such as that from a linear accelerator, interacts with patient tissues and various components of the accelerator, one of the primary outcomes is the release of low energy electrons. This occurs due to the ionization and excitation of atoms within the tissue and the accelerator's components as they absorb energy from the high-energy photon or particle beam.

As the primary beam penetrates the tissues, it can knock electrons off atoms, which results in the production of secondary electrons. These secondary or low energy electrons are crucial in radiation therapy because they contribute to the dose delivered to the tumor and surrounding tissues. They tend to have a larger distribution in tissue due to their lower energy and, thus, enable a more effective utilization of radiation near the tumor while sparing critical structures.

Furthermore, low energy electrons are significant in the context of radiation protection and risk assessment in clinical settings since they play a role in biological effects associated with radiation exposure.

While other particles like alpha particles, proton clusters, and neutrons may be generated in specific high-energy physics experiments or in certain rare interactions, they are not typically produced in significant quantities from standard treatment modalities used in a clinical setting with electron or photon beams. Therefore, low energy electrons are the most relevant and abundant secondary particles