Applying Block to reduce low-dose volume of lungs in helical tomotherapy of lung cancer(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2019年第2期
- Page:
- 152-156
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Applying Block to reduce low-dose volume of lungs in helical tomotherapy of lung cancer
- Author(s):
- ZHANG Jinjian; LI Zhiqiang; WEN Ting; WANG Yan; ZHONG Yu; CHEN Jing; LI Jing
- Helical Tomotherapy Center, PLA Guangzhou General Hospital, Guangzhou 510010, China
- Keywords:
- ; Keywords: non-small-cell lung cancer; helial tomotherapy; low-dose volume; radiotherapy dose
- PACS:
- R815
- DOI:
- DOI:10.3969/j.issn.1005-202X.2019.02.006
- Abstract:
- Abstract: Objective To study the method of reducing the low-dose volume of lungs by Block in helical tomotherapy of non-small cell lung cancer. Methods Twenty cases of non-small-cell lung cancer were selected in this study. For each case, the protected area was plotted as Block and the radiotherapy plan was designed according to the 3 different Block settings. Unblock mode was adopted in group I, Directional Block mode in group II, Complete Block+Directional Block mode in group III. After the optimization results met the dose limits of target areas and organs-at-risk, the dose distribution, dose-volume histogram and single treatment time were compared among 3 groups, and one-way ANOVA was used to analyze the differences of the relevant data. Results The V5 of lungs was (51.3±6.5)%, (37.4±5.0)%, (26.5±2.9)% in group I, II and III, respectively, and mean lung dose (MLD) was (10.4±0.5)%, (9.4±0.8)%, (8.2±1.0)%, respectively. Compared with those in group I, the V5 of lungs in group II and III was reduced by 27%, 48%, and MLD was decreased by 9.6%, 21%, respectively, with statistical differences. The homogeneity index of planning target volume (PTV) was 0.065±0.003, 0.082±0.006 and 0.084 ± 0.011 in group I, I and III, respective, and the difference was statistical significant. The conformity index of PTV was 0.77±0.07, 0.69±0.09 and 0.62±0.08 in group I, II and III, without statistical significance. The treatment time of group II and group III was (11.8 ± 0.6), (16.3 ± 2.3) min, respectively, which was 2.1 times and 2.9 times longer than (5.5±0.5) min in group I. Conclusion The use of Complete Block and Directional Block can reduce the V5 of normal lung tissue and decrease MLD, but affect the homogeneity index and conformity index of PTV (still meet the clinical requirements) and prolong the treatment time.
Last Update: 2019-02-26