Integrated helical fan-beam computed tomography in image-guided radiation treatment device

A method of acquiring projection data from a radiotherapy device including a first radiation source configured for therapeutic radiation and a second radiation source configured for imaging radiation coupled to a rotatable gantry system, comprising:

• controlling the second radiation source and a collimator assembly positioned relative to the second radiation source to provide a fan beam of radiation that exposes a single, continuous area of a radiation detector that is less than an active area of the radiation detector;
• controlling the rotatable gantry system and a patient support to provide a helical scan of a patient on the patient support;
• and
• providing imaging data from the active area of the radiation detector;
• wherein controlling the second radiation source and the collimator assembly is based on speed and image quality objectives.

A radiotherapy delivery device, comprising:

• a rotatable gantry system positioned at least partially around a patient support;
• a first radiation source coupled to the rotatable gantry system, the first radiation source configured for therapeutic radiation;
• a second radiation source coupled to the rotatable gantry system, the second radiation source configured for imaging radiation, wherein the second radiation source comprises an energy level less than the first radiation source;
• a radiation detector coupled to the rotatable gantry system and positioned to receive radiation from the second radiation source;
• a collimator assembly positioned relative to the second radiation source to selectively control a shape of a radiation beam emitted by the second radiation source to selectively expose a single, continuous area of the radiation detector to the radiation beam during a helical scan;
• a data processing system configured to:
• receive imaging data from an active area of the radiation detector;
• and
• reconstruct an image of a patient based on the imaging data during IGRT;
• wherein the collimator assembly selectively controls the shape of the radiation beam based on speed and image quality objectives.