Final answer:
The correct statement by the patient, 'I will need to buy a water bottle to carry with me,' indicates an understanding of dealing with the side effect of dry mouth due to radiation therapy, which is common and can be alleviated by staying hydrated.
Step-by-step explanation:
The correct statement by the patient that indicates effective teaching about radiation therapy is "I will need to buy a water bottle to carry with me." This reflects an understanding of the potential for a dry mouth and the need for hydration, which is a common side effect due to radiation therapy. Special mouthwashes are also advised instead of regular alcohol-based mouthwashes to help with dry mouth without causing irritation. It is important to manage skin care during radiation, and the use of gentle, non-irritating lotions might be recommended, contrasting the patient's incorrect belief that they should not use any lotions. Diarrhea is indeed a potential side effect, but not all patients will experience it. As for the consumption of alcohol-based mouthwashes, it is generally ill-advised as they can further irritate oral ulcers instead of cleaning them. Therefore, the patient's statement about carrying a water bottle signifies a grasp of measures to deal with the side effects of radiation therapy.