Journal of Radiation Research and Radiation Proces ›› 2018, Vol. 36 ›› Issue (6): 60202-060202.doi: 10.11889/j.1000-3436.2018.rrj.36.060202

• RADIOBIOLOGY AND RADIOMEDICINE • Previous Articles     Next Articles

Influence of CBCT online alignment technology on the target margin and analysis of dosimetric differences in intensity-modulated radiotherapy for postoperative patients suffered from cervical cancer

NIU Ruijun1,2, ZHANG Hui3,4, TAO Na1,2, JIA Huailin1,2, GUO Qing1,2, LIU Tingting1,2, TAO Fali1,2, OUYANG Shuigen1,2, GAO Liying1,2, ZHAO Lin1,2, WEI Shihong1,2, LIU Zhiqiang1,2, AN Yongwei1,2, WEI Xiyi1,2   

  1. 1 Gansu Provincial Cancer Hospital, Lanzhou 730050, China;
    2 Gansu Provincial Radiation Therapy Research Center, Lanzhou 730050, China;
    3 University of Chinese Academy of Sciences, Beijing 100049, China;
    4 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
  • Received:2018-08-06 Revised:2018-09-09 Online:2018-12-20 Published:2018-12-21
  • Supported by:

    Supported by Technology R&D Special Plan of Gansu Provincial Department of Science and Technology (1305TCYA009), Natural Science Foundation of Gansu Province (145RJZA178), and Health Industry Research Project of Gansu Province (GSWSKY-2015-29)


Two designs of planning target volume (PTV) of target margins were derived from the setup errors with or without cone-beam computed tomography (CBCT) online alignment. Different plans were designed with these two sets of PTV target margins using treatment planning systems (TPS). We analyzed dosimetric differences in the target and organ at risk (OAR) caused by different designs of PTV target margins. The two designs of PTV target margins in the X, Y and Z directions, respectively, were as follows:3.73, 5.16 and 4.36 mm and 5.5, 9.89 and 5.83 mm; these designs were derived from setup errors with or without CBCT online alignment. Significant statistical differences (p<0.05) were found among V30, V40, V50 and Dmean of the bladder and rectum; V20, V30, V40, V50 and Dmean of tne small intestine; V10, V20, V30, V40, V50 and Dmean of the marrow; and V50 and Dmean of the left and right femoral head. Significant statistical differences (p<0.05) were also found in D2, D5, D50 and Dmean of clinical target volume (CTV), homogeneity index (IH) and conformity index (IC). The dose in the OAR will on the high side if using larger target margin of PTV with CBCT online alignment, and the dose deficiency was significant in the target if using smaller target margin of PTV without CBCT online alignment. CBCT online alignment can reduce the setup errors and improve the accuracy of the patient positioning. The choice of PTV target margin should be related with the choice of CBCT online alignment, so as to avoid dose deficiency in the target and excessive radiation in the OAR to improve the radiotherapy quality.

Key words: Cone beam computed tomography, Online alignment technology, Cervical cancer, Radiotherapy, Target margin, Dosimetric difference

CLC Number: 

  • TL72