title: Analysis of precision in tumor tracking based on optical positioning system during radiotherapy.
abstract: Tumor tracking is performed during patient set-up and monitoring of respiratory motion in radiotherapy. In the clinical setting, there are several types of equipment for this set-up such as the Electronic Portal imaging Device (EPID) and Cone Beam CT (CBCT). Technically, an optical positioning system tracks the difference between the infra ball reflected from body and machine isocenter. Our objective is to compare the clinical positioning error of patient setup between Cone Beam CT (CBCT) with the Optical Positioning System (OPS), and to evaluate the traditional positioning systems and OPS based on our proposed approach of patient positioning. In our experiments, a phantom was used, and we measured its setup errors in three directions. Specifically, the deviations in the left-to-right (LR), anterior-to-posterior (AP) and inferior-to-superior (IS) directions were measured by vernier caliper on a graph paper using the Varian Linear accelerator. Then, we verified the accuracy of OPS based on this experimental study. In order to verify the accuracy of phantom experiment, 40 patients were selected in our radiotherapy experiment. To illustrate the precise of optical positioning system, we designed clinical trials using EPID. From our radiotherapy procedure, we can conclude that OPS has higher precise than conventional positioning methods, and is a comparatively fast and efficient positioning method with respect to the CBCT guidance system.
authors.affiliation: Department of Radiotherapy Center, Jinling Hospital, Nanjing, China.
authors.forename: Han
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Department of Radiotherapy Center, Jinling Hospital, Nanjing, China.
authors.forename: Junshu
authors.initials: J
authors.lastname: Shen
authors.affiliation: Department of Radiotherapy Center, Jinling Hospital, Nanjing, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Radiotherapy Center, Jinling Hospital, Nanjing, China.
authors.forename: Junting
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Radiotherapy Center, Jinling Hospital, Nanjing, China.
authors.forename: Xixu
authors.initials: X
authors.lastname: Zhu
authors.affiliation: School of Electronic Science and Engineering, Nanjing University, Nanjing, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ge
authors.affiliation: Department of Emergency, Shenzhen Hospital of Southern Medical University, Shenzhen, Guangdong Province, China.
authors.forename: Yongjian
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D006257:Head / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000532:radiotherapy*; D056888:Patient Positioning / Q000379:methods*; D019047:Phantoms, Imaging; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results
keywords: Cone BeamCT; Electronic Portal imagingDevice; linear accelerator; optical positioning system; patient setup error; radiotherapy procedure