Research on the precision and stability of optical surface imaging technology in guiding radiotherapy positioning

Objective To investigate the precision and stability of optical surface imaging (OSI) system Catalyst in guiding radiotherapy positioning. Methods A total of 52 patients with five different tumor sites who underwent cone-beam computed tomography (CBCT)-guided radiotherapy were recruited in this investigation. For the first treatment fraction, the setup error was recorded as C after online CBCT correction, and the surface images of patients taken by Catalyst were set as the reference images Cref. For the following treatment fraction, patients were pre-corrected according to the Catalyst Cref image with the acceptable errors within 2 mm/ 2, and the pre-corrected errors were recorded as C1.Then, after online CBCT correction, the setup errors were recorded as C. The errors between post-corrected Catalyst surface image and Cref image were recorded as C2.For each treatment fraction, the difference between Catalyst correction errors C1 and CBCT corrected errors C was recorded as d1, and the difference between the post-corrected Catalyst errors C2 and Cref image was recorded as d2. d3=d1-d2.The values of d1 and d3 in the 6 dimensions were analyzed using single sample t-test. The correlation between C-C1 and d1-d2 was statistically analyzed by Pearson correlation analysis. Results The mean value of d1 and d3 for 52 patients were within 2 mm/ 2 °. CBCT-C1 and d1-d2 were both significantly correlated (R=3, 7, P=0.00, 0.01). Conclusions OSI system yield high accuracy and stability in radiotherapy positioning, which is of certain significance in radiotherapy positioning for cancer patients. Key words: Optical surface imaging; Tomography, X-ray computed, cone-beam; Active breathing control