The electrons contained within high energy photon beams may result from photon interactions with the:

When high energy photon beams interact with collimators, secondary electrons are produced as a consequence of photon interactions with the material of the collimators. Collimators are typically made from dense materials such as lead or tungsten, which can effectively interact with high energy photons.

As photons collide with the nuclei of the atoms in the collimator, they can transfer energy, resulting in the ejection of electrons from these atoms. These ejected electrons can contribute to the therapeutic dose delivered to the patient during radiation therapy.

This interaction process highlights the importance of the design and material of the collimators in shaping the radiation beam and determining the distribution of dose in the target tissue, which is critical for effective treatment planning in radiation therapy.

The photon interactions leading to the creation of secondary electrons are not primarily associated with room air, bolus material, or lucite trays. Room air has lower density and a lower atomic number compared to collimators, making it less effective for significant photon interactions. Bolus is used to bring the dose closer to the surface in certain situations but does not primarily generate electrons from photon interactions. Lucite trays may serve specific functions, such as supporting bolus or other accessories but are not the primary site of significant