FOUR-DIMENSIONAL (4D) IMAGE VERIFICATION IN RESPIRATORY GATED RADIATION THERAPY

摘要

A method for four-dimensional (4D) image verification in respiratory gated radiation therapy, includes: acquiring 4D computed tomography (CT) images, each of the 4D CT images representing a breathing phase of a patient and tagged with a corresponding time point of a first surrogate signal (102); acquiring fluoroscopic images of the patient under free breathing, each of the fluoroscopic images tagged with a corresponding time point of a second surrogate signal (110); generating digitally reconstructed radiographs (DRRs) for each breathing phase represented by the 4D CT images (116); generating a similarity matrix to assess a degree of resemblance in a region of interest between the DRRs and the fluoroscopic images (117); computing a compounded similarity matrix by averaging values of the similarity matrix across different time points of the breathing phase during a breathing period of the patient (118); determining an optimal time point synchronization between the DRRs and the fluoroscopic images by using the compounded similarity matrix (120); and acquiring a third surrogate signal and turning a treatment beam on or off according to the optimal time point synchronization (128).