Demonstration of quasi-real-time intrafractional motion in esophageal cancer radiotherapy provided by ExacTrac X-ray snap verification

Article type: Research Article

Authors: Duan, Jinghao^{a; b} | Guo, Ran^c | Wei, Wenqiang^b | Zhu, Jian^b | Qiu, Qingtao^b | Zhang, Ruohui^d | Meng, Xiangjuan^{e; *}

Affiliations: [a] School of Precision Instrument and Opto-electronics Engineering, Tianjin University, Tianjin, China | [b] Department of Radiotherapy, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China | [c] Department of Radiation Oncology, Jining NO.1 People’s Hospital, Jining, China | [d] Department of Radiotherapy, the Fourth Hospital of Hebei Medical University, Shijiazhuang, China | [e] Department of Clinical Laboratory, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, China

Correspondence: [*] Corresponding author: Xiangjuan Meng, Department of Clinical Laboratory, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, China. Tel.: +86 053167626292; Fax: +86 053167626292; E-mail: xj_meng@163.com.

Abstract: OBJECTIVE:To investigate the following hypotheses: (1) ExacTrac X-ray Snap Verification (ET-SV) is an alternative to CBCT for positioning patients with esophageal carcinoma (EC), (2) ET-SV can detect displacement in EC patients during radiotherapy (RT) and (3) EC patients can be feasibly monitored in quasi-real-time with ET-SV during RT. METHODS:Anthropomorphic phantoms and 13 patients were included in this study. CBCT and ET-SV were both implemented before treatment delivery to detect displacement, and their correction results were compared. For the patient tests, positional correction in 3 translational directions and the yaw direction were applied using the ET-SV correction results. The residual error was detected immediately using ET-SV. Finally, to acquire the intrafractional motion, ET-SV was implemented when the gantry was at 0°, 90°, 180° and 270°, respectively. RESULTS:In phantom tests, the maximum value of the difference in displacement between the CBCT and ET systems was 1.16 mm for translation and 0.31° for yaw. According to Bland–Altman analysis of the patient test results, 5% (5/98), 5% (5/98), 5% (5/98), and 4% (4/98) of points were beyond the upper and lower limits of agreement in the AP, SI, LR and yaw directions, respectively. The mean residual error was –0.482 mm, 1.215 mm, 1.0 mm, –0.487°, 0.105°, and 0.003° in the AP, SI, LR, pitch, roll and yaw directions, respectively. The intrafractional displacement ranged from –0.21 mm to 0 mm for translation and from –0.63° to 0.21° for rotation. The mean total translational error for intrafractional motion increased from 0.47 mm to 1.14 mm during the treatment. CONCLUSION:The accuracy of ET-SV for EC RT positional correction is comparable to that of CBCT. Thus, Quasi-real-time intrafractional monitoring can be used to detect EC patient displacement during radiotherapy.

Keywords: Quasi-real-time monitoring, esophageal cancer, ExacTrac X-ray Snap

DOI: 10.3233/XST-221165

Journal: Journal of X-Ray Science and Technology, vol. 30, no. 4, pp. 677-687, 2022