What should i avoid doing during radiation therapy treatment?

Smoking/ Vit E: Mega dose of antioxidants, vitamin e, excess sun exposure to the treatment area, usually excessive alcohol or tobacco ( the more oxygen around, the more effective the radiation).

Depends on site: The activities, diet, medications, etc to avoid during radiation depend heavily on where you are receiving radiation. Your radiation oncologist administering your treatments is the best source of information for you in this regard.