Can a cyberknife be used to treat limited small cell lung cancer?

There is no. Cogent role for cyberknife in sclc and it would be a misuse of that expensive technology. Chemotherapy is the standard for limited or extensive disease, thoracic radiotherapy with linac is standard in disease confined to chest. All those warrant preventitive radiotherapy to the brain if the chest responds.
Yes. By cyberknife ( trade name ) a system focused precise radiation will be given just to cancer area only with out injuring adjacent normal tissue as in brain , lung , pancreatic tumors. Small cell lung cancer is an indication for radiation therapy.
It depends. The term "limited" when applied to lung cancer can mean anything from a pinpoint of a tumor to tumor taking up half of the chest. The term is very misleading. Please accept my apologies on behalf of the medical establishment for use of that term. If the patient has only a single tumor, and especially if the tumor is relatively small, cyberknife can be an excellent choice. Chemo also needed.
Yes. However, it would not be the best treatment. If someone is very weak then it could be a consideration. Small cell lung cancer in the limited stage should be treated with chemotherapy and radiation therapy at the same time. This type of cancer spreads to distant organs so if treated with radiation therapy alone, distant disease will develop. Hope this helps.