Ans. is 'd' i.e. Damage to nearby structures is significant* Streotactic radiosurgery is a form of radiation therapy that focuses high powered X-rays on a small area of the body. Stereotactic radiosurgery better focuses teh radiation on the abnormal area. Despite its name, radiosurgery is a form of radiation therapy, not a surgical procedure. Stereotactic radiosurgery is often used to slow down the growth of small, deep brain tumors that are hard to remove during surgery. Such therapy may also be used in patients who are unable to have surgery, such as the elderly or those who are sick.* In Stereotactic radiosurgery, focused high dose of radiation is administered to a precisely defined volume of tissue in a single treatment, usually using the gamma Knife. Gamma knife contains Cobalt-60 sources of approximately 30 curis placed in circular array in a heavily shielded unit. The unit directs the gamma rays to the target. Besides gamma knife, X-ray knife (linear accelerator) and cyclotron (proton beam) are also used.* Advantage of stereotactic radiosurgery are: -i) Achieve tumor ablation without surgery.ii) Damage to nearby structure is minimized as radiation is delivered to focused area.iii) Tumor ablation can be achieved in difficult location, e.g., brainUses of stereotactic surgery* The most important use of stereotactic surgery is for brain tumors and the use of stereotactic surgery was once limited to brain tumors. But today it may be used to treat many other diseases and conditions.Uses of Stereotactic radiosurgeryTumors in Nervous systemOther conditionsOther cancers for which radiosurgery is being used or studied* Brain tumors (including metastasis)* Acoustic neuroma* Head & Neck (e.g., nasopharyngeal carcinoma)* Pituitary tumors* Spinal cord tumors* Cancer of eye (uveal melanoma)* AV malformation* Movement disorders* Parkinsonism* Some type of epilepsy* Trigeminal neuralgia* Liver cancer* Lung cancer (Stage I inoperable)* Prostate cancer