The realization and application on image pasting for Cone-beam Computed Tomography

Abstract

Objective To enlarge the scan width of Cone-beam Computed Tomography (CBCT) and offer the integrity of structures (including tumor targets and organs at risk) on CBCT images by pasting the CBCT images together without gap and lose data out. Methods Give the patient CBCT scan two times at different longitude position. Import the two CBCT image series to TPS and then fusion the planning CT and CBCT together. Find the same layer of two CBCT series by analyzing the two fusion results and remember their sequence number. Offer the CBCT image series and the sequence number to “CBCT Pasting” which is the software we developed in this investigating. Then the software will merge the CBCT series into the same reference frame. To validate the feasibility of CBCT Pasting, we observe its geometric characteristics by patients and phantoms. Result The volume of phantom has the difference 0.26% (28.34 cm³) between CT and CBCT images and 1.87% (12.82 cm³), 1.47% (10.07 cm³) for the two lungs. On the images of patients, the difference is 1.97% (64.53 cm³) for total-lung, 2.30% (33.32 cm³) for lung left and 1.75% (31.21 cm³) for lung right. Conclusion This work proved that the CBCT scan and pasting can enlarge the scan width without image data loosing. This technique can provide the chance to observe the whole target and OAR and the chance for physicists to evaluating the treatment plan and even replanning.