Image guided radiotherapy apparatus and control method therefor

A control method for a radiotherapy apparatus, the apparatus comprising a treatment unit which comprises a treatment head for generating radiation beam for radiotherapy;

• an imaging unit integratedly mounted with the treatment head for imaging a target area of a patient;
• and a planning unit connected to the treatment unit and the imaging unit via a connecting cable,
• wherein the control method comprises:
• positioning the radiotherapy apparatus so that the center point of a treatment area coincides with a virtual isocenter of the radiotherapy apparatus;
• obtaining an optical image of the treatment area by using the imaging unit;
• using the planning unit to generate an anatomical structure contour of the target area based on the optical image;
• and
• determining, by the planning unit, a size parameter and/or motion parameter of the treatment unit based on the anatomical structure contour, and sending the motion parameter to the treatment unit for execution.