title: The clinical feasibility and performance of an orthogonal X-ray imaging system for image-guided radiotherapy in nasopharyngeal cancer patients: Comparison with cone-beam CT.
abstract: The demand for greater accuracy of intensity-modulated radiotherapy (IMRT) has driven the development of more advanced verification systems for image-guided radiotherapy (IGRT). The purpose of this study is to investigate setup discrepancies measured between an orthogonal X-ray guidance system (XGS-10) and cone-beam computed tomography (CBCT) of Varian in the IMRT of patients with nasopharyngeal cancer (NPC). The setup errors measured by XGS-10 and CBCT at the treatment unit with respect to the planning CTs were recorded for 30 patients with NPC. The differences in residual setup errors between XGS-10 system and CBCT were computed and quantitatively analyzed. The time of image acquisition and image registration was recorded. The radiation doses delivered by CBCT and XGS-10 were measured using PTW0.6CC ionization chambers and a water phantom. The differences between setup errors measured by the XGS-10 system and CBCT were generally <1.5 mm for translations, indicating a reasonably good agreement between the two systems for patients with NPC in the translation directions of A-P (P = 0.856), L-R (P = 0.856) and S-I (P = 0.765). Moreover, compared with CBCT, XGS-10 took much shorter image acquisition and registration time (P <0.001) and delivered only a small fraction of extra radiation dose to the patients (P <0.001). These results indicate that XGS-10 offers high localization accuracy similar to CBCT and additional benefits including prompt imaging process, low imaging radiation exposure, real time monitoring, which therefore represents a potential attractive alternative to CBCT for clinical use.
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Li-Rong
authors.initials: LR
authors.lastname: Zhao
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Yi-Bing
authors.initials: YB
authors.lastname: Zhou
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Guang-Hui
authors.initials: GH
authors.lastname: Li
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Qi-Ming
authors.initials: QM
authors.lastname: Li
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Ding-Qiang
authors.initials: DQ
authors.lastname: Yang
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Han-Xu
authors.initials: HX
authors.lastname: Li
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Jiu-Qing
authors.initials: JQ
authors.lastname: Wan
authors.affiliation: Cancer Institute of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. Electronic address: sunjg09@aliyun.com.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Sun
mesh_terms: D000465:Algorithms; D002277:Carcinoma; D003198:Computer Simulation; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011859:Radiography / Q000379:methods*; D011874:Radiometry; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014867:Water; D014965:X-Rays
chemical_list: D014867:Water
keywords: CBCT; IGRT; Nasopharyngeal cancer; Residual setup errors; Setup discrepancies; XGS-10