This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiation treatment planning, Subject name: Radiology
Gamma knife is used in? 
Select and explain. 
A. Radiotherapy, B. Chemotherapy, C. Nuclear medicine, D. Radioisotope scan
A: Radiotherapy
Answer: A: Radiotherapy 
Explanation: ANSWER: (A) RadiotherapyREF: Practical Radiotherapy physics and equipment Pam Cherry Angela M. Duxbury 2nd Edition page 132, http://en.wikipedia.org/wiki/RadiosurgeryRadiosurgery is a medical procedure that allows non-invasive treatment of benign and malignant tumors. It is also known as stereotactic radiotherapy, (SRT) when used to target lesions in the brain, and stereotactic body radiotherapy (SBRT) when used to target lesions in the body. Inaddition to cancer, it has also been shown to be beneficial for the treatment of some non-cancerous conditions, including functional disorders such as arteriovenous malformations (AVMs) and trigeminal neuralgia.