Journal of Radiation Research and Radiation Processing ›› 2020, Vol. 38 ›› Issue (5): 20-25.doi: 10.11889/j.1000-3436.2020.rrj.38.050301

• RADIOBIOLOGY AND RADIOMEDICINE • Previous Articles    

Actual absorbed dose in radiotherapy of patients with rectal cancer based on cone-beam CT

CHEN Liming1,FU Juan1,ZHANG Yanlong2,MING Xin3,WANG Keqiang2,DUAN Jinghao2,MENG Huipeng1,2()   

  1. 1.Characteristic Medical Center of PAP, Tianjin 300162, China
    2.School of Precision Instrument and Opto-electronics Engineering, Tianjin University, Tianjin 300072, China
    3.School of Biomedical Engineering, Tianjin Medical University, Tianjin 300050, China
  • Received:2020-05-06 Revised:2020-05-27 Accepted:2020-05-27 Online:2020-10-20 Published:2020-10-19
  • Contact: MENG Huipeng E-mail:hongyi1218@163.com
  • About author:CHEN Liming (male) was born in July 1985, and obtained his bachelor’s degree from North China Coal Medical College in 2010. Now he majors in gastroenteric tumor-related research, attending physician
  • Supported by:
    National Natural Science Foundation of China(11805144);Science & Technology Development Fund of Tianjin Education Commission for Higher Education(2017KJ231)

Abstract:

In the radiotherapy of rectal cancer, the actual dose received by the patient's body always differs from the planned design due to setup errors. Twenty rectal cancer cases undergoing RapidArc treatment were selected. The treatment plan of the pCT images was transplanted to the scatter-corrected cone-beam computed tomography (CBCT) images. Then, the dose was calculated to generate the revised CBCT plan after the raw CBCT plan was corrected using the weekly setup error data. Finally, a paired t-test was used to compare the results of the dose calculation between the CBCT and pCT plans. This showed that the dosimetric parameter average values of D2, D98, D50, CI, and HI in the target of the CBCT plan were lower than those in the pCT plan. The differences of 2.8%, 2.5%, 2.9%, 2.0%, and 4.4%, respectively, were statistically significant (p<0.001). The dosimetric parameter average values of Dmean, D5, V20, V30, and V40 in the small intestine of the CBCT plan were higher than those in the pCT plan. The differences of 3.0%, 3.1%, 2.5%, 3.1%, and 3.6%, respectively, were statistically significant (p<0.001). The dosimetric parameter average values of Dmean, D5, V20, V30, and V40 in the bladder of the CBCT plan were higher than those in the pCT plan. The differences of 3.0%, 1.8%, 0.9%, 3.2%, and 3.4%, respectively, were statistically significant (p<0.001). The difference between the left and right femoral heads was small (maximum difference: 0.3%, minimum difference: 0.1%); however, statistical significance was found (p<0.001). The comparative analysis indicates that the CBCT plan, based on scatter-corrected CBCT images combined with setup error data, provides a reference for the actual absorbed dose of each tissue in rectal cancer radiotherapy. These findings are useful for the quantitative evaluation of the therapeutic effect of radiotherapy for rectal cancer.

Key words: Cone-beam CT(CBCT), Absorbed dose, Rectal cancer, Radiotherapy

CLC Number: 

  • TL72