Patent Number: 
Section: claims

1. A method, implemented by a computing system programmed to perform the following, comprising:determining a full motion range of a target, wherein the full motion range of the target defines an internal target volume (ITV);identifying a partial motion range of the target, wherein the partial motion range is an untracked portion of the full motion range of the target comprising one of an untracked plane or an untracked axis; andgenerating a partial-ITV based on the identified partial motion range, wherein the partial-ITV is a volume swept by the target as the target moves through the partial motion range, the partial-ITV being smaller than the ITV. 2. The method of claim 1, wherein determining the full motion range of the target comprises:acquiring two preoperative images of the target that show two different positions of the full motion range;receiving delineations of the target in the two preoperative images; andinterpolating the full motion range of the target based on the delineations of the target in the two preoperative images. 3. The method of claim 1, further comprising:generating a treatment plan to deliver treatment to the partial-ITV. 4. The method of claim 3, wherein identifying the partial motion range comprises at least one of receiving a user selection of the partial motion range or automatically computing the partial motion range based on at least one of a tracking mode or a treatment mode identified in the treatment plan. 5. The method of claim 1, wherein the target travels through the full motion range during a respiration cycle of a patient, the method further comprising:monitoring the respiration cycle of the patient based on external markers; andgenerating a respiration model that correlates positions of the external markers to phases of the respiration cycle and to a target position. 6. The method of claim 5, further comprising:when the patient is in one or more particular phases of the respiration cycle, activating a radiation treatment beam to treat the partial-ITV, wherein the partial-ITV includes all possible target positions during the one or more particular phases of the respiration cycle; andwhen the patient is in other phases of the respiration cycle, deactivating the radiation treatment beam. 7. The method of claim 1, the method further comprising:determining when the target is located at positions that are within the partial-ITV;while the target is located at the positions within the partial-ITV, activating a radiation treatment beam to treat the volume swept by the target as the target moves through the partial motion range; anddeactivating the treatment beam while the target is outside of the partial-ITV. 8. The method of claim 1, wherein a tracking mode that tracks the target along a single axis will be used during treatment, the method further comprising:identifying the partial motion range by projecting the full motion range of the target onto a plane that is normal to the tracked axis, wherein the partial-ITV covers a motion range of the target the untracked plane. 9. The method of claim 1, wherein a tracking mode that tracks the target along a single imaging plane will be used during treatment, the method further comprising:identifying the partial motion range by projecting the full motion range of the target onto an axis that is normal to the single imaging plane, wherein the partial-ITV covers a motion range of the target in the untracked axis. 10. The method of claim 1, further comprising:aligning a reference structure to a treatment center of a treatment system in three dimensions (3D) by acquiring images by a first image detector and a second image detector and registering the images to a preoperative 3D image;aligning a center of the partial-ITV to the treatment center based on a known offset between the reference structure and the center of the partial-ITV;tracking target position in an imaging plane that is parallel to a treatment plane that intersects the treatment center using one of the first image detector or the second image detector; andconverting image data from the first image detector or the second image detector into 3D positional data by projecting a 2D target position identified in the image data onto the treatment plane. 11. The method of claim 1, further comprising:aligning the target to a treatment center of a treatment system in three dimensions (3D) by acquiring a 3D image of the patient and performing a registration between said 3D image and a previous 3D image of the patient; andtracking target position in an imaging plane using a first image detector. 12. A treatment planning system, comprising:a memory to store instructions for image guided treatment planning; anda processing device coupled to memory, the processing device configured to:determine a full motion range of a target, wherein the full motion range of the target defines an internal target volume (ITV);identify a partial motion range of the target, wherein the partial motion range is an untracked portion of the full motion range of the target comprising one of an untracked plane or an untracked axis;generate a partial-ITV based on the identified partial motion range, wherein the partial-ITV is a volume swept by the target as the target moves through the partial motion range, the partial-ITV being smaller than the ITV; andgenerate a treatment plan that includes instructions for delivering treatment to the partial-ITV. 13. The system of claim 12, wherein the processing device is further configured to:receive delineations of the target in two preoperative images that show two different positions of the motion range; andinterpolate the full motion range of the target based on the delineations of the target in the two preoperative images. 14. The system of claim 12, wherein identifying the partial motion range comprises at least one of receiving a user selection of the partial motion range or automatically computing the partial motion range based on at least one of a tracking mode or a treatment mode identified in the treatment plan. 15. The system of claim 12, further comprising:a motion tracking system to monitor a respiration cycle of a patient based on external markers, wherein the target travels through the full motion range during the respiration cycle of the patient;wherein the processing device is further configured to generate a respiration model that correlates positions of the external markers to phases of the respiration cycle and to a target position; andwherein the treatment plan is for gated radiation treatment in which a radiation treatment beam is activated while the target is located within the partial-ITV and is deactivated while the target is located outside of the partial-ITV. 16. The system of claim 1, wherein the tracking mode tracks the target along a single axis, and wherein the processing device is further configured to identify the partial motion range by projecting the full motion range of the target onto a plane that is normal to the tracked axis, wherein the partial-ITV covers a motion range of the target in the untracked plane. 17. The system of claim 1, wherein the tracking mode tracks the target along a single imaging plane, and wherein the processing device is further configured to identify the partial motion range by projecting the full motion range of the target onto an axis that is normal to the single imaging plane, wherein the partial-ITV covers a motion range of the target in the untracked axis. 18. A treatment delivery system comprising:a treatment bed to support a patient during a treatment;at least one imager to generate images of the patient that include a target during treatment;a radiation source to generate a radiation treatment beam; anda processor to perform the following, comprising:load a treatment plan, wherein the treatment plan identifies a partial internal target volume (partial-ITV), the partial-ITV including a volume swept by the target as the target moves through a partial motion range, wherein the partial motion range is a subset of a full motion range of the target that defines an internal target volume (ITV);align a center of the partial-ITV to a treatment center of the treatment delivery system based on positioning the treatment bed;monitor a current target position based on images generated by the at least one imager; andactivate the radiation source to deliver the radiation treatment beam to the partial-ITV while minimizing radiation delivered to areas outside of the partial-ITV. 19. The treatment delivery system of claim 18, wherein the at least one imager comprises an x-ray imager that has an imaging plane, and wherein the partial motion range corresponds to motion along an untracked axis that is normal to the imaging plane, further comprising the processor to:track the current target position within the imaging plane in two dimensions (2D) based on x-ray images generated by the x-ray imager;convert a 2D target position determined from the x-ray images into three dimensional (3D) positional data by projecting the 2D target position onto a treatment plane, wherein the treatment plane is a plane that passes through the treatment center and that is plane parallel to the imaging plane; andreposition the radiation source to deliver the radiation treatment beam to the target based on the current target position. 20. The treatment delivery system of claim 18, wherein the treatment delivery system is a gantry based system configured to perform gated treatment delivery, and wherein the processor is configured to activate the radiation source when the target is located within the partial-ITV and to deactivate the radiation source when the target is located outside of the partial-ITV. 21. The treatment delivery system of claim 20, further comprising:a motion detecting device to track positions of one or more external markers disposed on the patient;wherein the processing device is further configured to determine when the target is located within the partial-ITV and when the target is located outside of the partial-ITV based on correlating the positions of the one or more external markers to locations of the target using a respiratory model. 22. The treatment delivery system of claim 18, wherein the at least one imager includes an electronic portal imaging device (EPID), and wherein the processor is further configured to perform the following, comprising:track the current target position within an imaging axis in one dimension (1D) based on the images, which are generated by the EPID; andreposition the radiation source to deliver the radiation treatment beam to the target based on the current target position, wherein the processor accounts for target motion outside of the imaging axis by treating the partial-ITV, the partial-ITV including the volume swept by the target in a plane to which the imaging axis is normal.