<qa>  What is the minimum maintenance duration of 6 months?The eligibility criteria are patients with unresectable HCC; good performance status; no prior radiotherapy for the liver; clinical measurable tumor; good liver function and good compliance. After entering this study, the testee will receive RT to hepatic tumor with concurrently sorafenib with a dose of 400 mg twice daily. Hepatic RT will be performed with a daily fraction size of 2.0 to 2.5 Gy to a total dose of 46 Gy to 60 Gy. After RT, maintenance sorafenib with a dose of 400 mg twice daily will be ongoing. Sorafenib will be continued until the occurrence of clinical or radiologic progression, or the occurrence of either unacceptable adverse events or death. Minimum maintenance duration of 6 months is recommended, but not mandatory. 