In relation to the aim of internal shielding in electron beam therapy, what primary outcome should be avoided?

In electron beam therapy, internal shielding serves to protect the skin and underlying tissues from unnecessary radiation while delivering an effective dose to the target area. The primary aim is to ensure that while the radiation is focused on the tumor or target area, there is minimal impact on the surrounding healthy tissues, particularly the skin, which is often the first tissue encountered by the electron beam.

Excessive skin dose should be avoided because high doses of radiation to the skin can lead to acute and chronic skin reactions, such as dermatitis, ulceration, and fibrosis. These conditions can cause significant morbidity and may affect the patient's quality of life. By effectively utilizing internal shielding, dosimetrists can ensure that the skin receives a dose that is within safe limits while still allowing the prescribed dose to be delivered to the tumor. This balance is crucial for maximizing treatment efficacy while minimizing adverse effects.

While under dosing the target area, severe patient discomfort, and increased treatment time are also important considerations in treatment planning, they are secondary to the critical need to avoid excessive skin dose, as skin toxicity can severely compromise the safety and tolerability of radiation therapy.