What two important effects must be considered when planning with electron beams due to the presence of bone?

When planning with electron beams, particularly in the context of their interaction with bone, it is crucial to understand that bone has a higher density compared to surrounding soft tissue. This density impacts how the electron beams behave as they penetrate various materials.

One important effect to consider is the reduction in dose behind the bone. When electrons collide with bone, some of their energy is absorbed, which diminishes the dose that would otherwise be delivered to tissues located deeper, beyond the bone. This phenomenon occurs because the electron beam's energy gets attenuated by the dense structure of the bone.

Additionally, the lateral scattering of electrons is significant. As electrons interact with tissues, especially denser materials like bone, they will scatter laterally. This scattering can lead to an increased dose in the surrounding tissues, which must be carefully planned for in dosage calculations to ensure that the intended treatment area receives the appropriate amount of radiation, while also protecting surrounding critical structures.

Considering both of these effects—reduced dose in regions behind bone and increased lateral scattering—is essential for optimal treatment planning with electron beams. It helps dosimetrists balance adequate doses for tumor control while minimizing unwanted side effects to adjacent normal tissues.