Setup errors and margins of CBCT-guided IMRT in different positions for uterine neoplasms(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2018年第10期
- Page:
- 1122-1127
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Setup errors and margins of CBCT-guided IMRT in different positions for uterine neoplasms
- Author(s):
- OUYANG Shuigen; SU Qun; TAO Na; GUO Qing; LIU Tingting; LIU Zhiqiang; WEI Xiyi; NIU Ruijun; TAO Fali
- Department of Radiation Oncology, Gansu Provincial Cancer Hospital, Lanzhou 730050, China
- Keywords:
- ; uterine neoplasm; image-guided radiotherapy; cone-beam computer; setup error; margin
- PACS:
- R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2018.10.002
- Abstract:
- Objective To study the setup errors and margins in intensity-modulated radiotherapy guided by kV-cone-beam computed tomography (CBCT) for patients with uterine neoplasms who were in prone or supine position. Methods Before radiotherapy began, Elekta Synergy with on-board imager was used to perform CBCT scans on 251 patients with uterine neoplasms, including 117 patients in supine position and 134 in prone position. The setup errors in left-right (x), superior-inferior (y) and anterior-posterior (z) directions were obtained by the registration between the automatically reconstructed images and the planned CT image. Moreover, the margins of planning target areas were also calculated. Results A total of 3 128 CBCT scans were performed on all patients, including 1 679 scans in prone position and 1 449 scans in supine positions. In 981 scans (31.36%), the error of any axis (x, y, z) was less than 0.3 cm; and in 415 scans (13.27%), the deviation distance from the ioscenter was found to be less than 0.3 cm. When the error direction was considered, the setup errors in x, y and z directions were (0.109 5±0.380 7), (-0.035 1±0.569 2), (0.075 1±0.285 2) cm for prone position, and (0.001 1±0.303 4), (0.118 4±0.583 0), (0.033 2±0.248 0) cm for supine position. When the size of the setup error was considered, the setup errors in x, y and z directions were (0.300 8±0.257 7), (0.442 8±0.359 2), (0.227 1±0.188 2) cm for prone position, and (0.229 3±0.198 6), (0.470 2±0.364 4), (0.183 2±0.170 3) cm for supine position. The margins of planning target area in x, y, z directions were 0.540, 0.486, 0.387 cm for prone position and 0.215, 0.704, 0.257 cm for supine position. Conclusion The setup errors of the patients with uterine neoplasms who are in supine versus prone position have differences. The deviation distance from the ioscenter less than 0.3 cm should be used for the calibration of setup errors. The margins of target areas in x, y, z directions are 0.540, 0.486, 0.387 cm for prone position, and 0.215, 0.704, 0.257 cm for supine position.
Last Update: 2018-10-22