Displacements of pulmonary tumors with the changes of respiratory patterns in fractionated radiotherapy(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2018年第5期
- Page:
- 509-513
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Displacements of pulmonary tumors with the changes of respiratory patterns in fractionated radiotherapy
- Author(s):
- SHI Yujing1; LI Jinkai2; JU Mengyang1; ZHENG Hailun2; SUN Xinchen2
- 1. Department of Special Medicine, Nanjing Medical University, Nanjing 210009, China; 2. Department of Radiation Oncology, the First Affiliated Hospital of Nanjing Medical University, Nanjing 210009, China
- Keywords:
- ; pulmonary tumor; four-dimensional cone beam computed tomography; respiratory phase; respiratory pattern; range of respiratory motion
- PACS:
- 【收稿日期】2018-01-22
- DOI:
- DOI:10.3969/j.issn.1005-202X.2018.05.003
- Abstract:
- Objective To evaluate the displacements and motions of pulmonary tumors with the changes of respiratory patterns in radiotherapy by four-dimensional cone beam computed tomography (4DCBCT). Methods 4DCT images and 125 CBCT images were collected from 25 patients. Image matching between CBCT images and planning CT images was carried out with the use of dual registration (Clipbox and Mask). The change of respiratory patterns was defined as the change of the ratio of time spent in inspiration versus time spent in expiration, I/E ratio, in each CBCT image, and the difference between extrema in Mask registration was used to indicate the changes of the range of respiratory motion. Results With the progression of fractionated treatment, the mean I/E ratio was 1.10±0.12, and the change was related to the treatment fraction and different patients (F=3.890, P=0.000). The time weight of inspiratory phase and expiratory phase was （52±3）% and （47±3）%, respectively. The relative displacements of tumors were 0.20, 0.39 and 0.19 cm in X, Y and Z directions, respectively, and the deviation in Y direction had statistical significance (F=2.070, P=0.040). The changes of the range of respiration motion were consistent with the displacements of tumors: the changes in superior-inferior direction were always larger than those in the other directions. The changes of the range of respiratory motion was not significantly related to radiotherapy fractions (F=0.498, P=0.790) but was found to be related to the size and location of tumor (r=0.720, P=0.000; r=0.360, P=0.018). Conclusion Real-time 4DCBCT-guided radiotherapy is suitable for those patients who have large respiratory motions and who have considerable tumor displacements. The change of respiratory patterns affects the internal target volume so effectively that physicists should design plans based on the respiratory patterns.
Last Update: 2018-05-22