How image quality affects determination of target displacement when using kV cone-beam computed tomography (CBCT)

Abstract

The advent of kV cone-beam computed tomography (CBCT) integrated with a linear accelerator allows for more accurate image-guided radiotherapy (IGRT). IGRT is the technique that corrects target displacement based on internal body information. To do this, the CBCT image set is acquired just before the beam is delivered and registered with the simulation CT image set. In this paper, we compare the registration results according to the CBCT?s reconstruction quality (either high or medium). A total of 56 CBCT projection data from 6 patients were analyzed. The translation vector differences were within 1 mm in all but 3 cases. For rotation displacement difference, components of all three axes were considered and 3 out of 168 (56  3 axes) cases showed more than 1 of rotation differences.