Patent ID: 7349522

Claim:
A method for dynamic radiation therapy simulation of a treatment plan for a patient, comprising the steps of: storing on a computer readable medium a set of reference images of the patient, planning a multi-leaf collimator plan for dynamic radiation therapy for the patient comprising a sequence of plan images and storing said plan images on a computer readable medium; acguiring a sequence of real-time fluoroscopic images of the patient over at least one respiration cycle of the patient; correcting image intensifier distortion of said fluoroscopic images in real-time; and displaying the plan or reference images overlying the corrected fluoroscopic images in real-time; wherein a respiration cycle indicator indicates the respiratory cycle by changes in the circumference of the patient's chest; and wherein said respiration cycle indicator comprises a belt for encircling the patient's chest, said belt having an elastic portion extending between a first point and a second point on said belt; a tube having a first end in a fixed relationship to said first point; a flexible wire having a first end affixed to said second point, said wire passing through said tube and extending beyond a second end of said tube; a radio-opaque marker attached to a second end of said flexible wire whereby changes in circumference of the patient's chest effect a linear translation of said marker.