Dosimetric impact of computational grid size in Monaco treatment planning system on small organs-at-risk in patients with head and neck cancer(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2019年第10期
- Page:
- 1145-1151
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Dosimetric impact of computational grid size in Monaco treatment planning system on small organs-at-risk in patients with head and neck cancer
- Author(s):
- PEI Yuntong; HU Jinyan; MA Yangguang; WANG Haiyang; LIU Lele; JI Tengfei; GUO Yuexin
- Department of Radiation Oncology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 453003, China
- Keywords:
- ; Monaco; computational grid; small organs-at-risk; dosimetry
- PACS:
- R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2019.10.006
- Abstract:
- Abstract: Objective To investigate the dosimetric effects of computational grid size in Monaco treatment planning system on the small organs-at-risk (OAR) in patients with head and neck cacer. Methods Ten patients with head and neck NKT (extranodal NK/T-cell lymphoma) were enrolled in the study, and two groups (groups A and B) of radiotherapy plan with different grid sizes were designed by Monaco treatment planning system. The plans in group A were optimized with 3 mm grid, and then 4 new plans were obtained by recalculating the final dose with the grid of 1, 2, 4 and 5 mm; in group B, 5 plans were generated with different grids (1, 2, 3, 4 and 5 mm). The other parameters in groups A and B remain unchanged, and the dose distribution was normalized to a prescription dose of 95% of planning target volume. The maximum, minimum and mean doses of lens, planning organ at risk volume (PRV) of lens, optic chiasm and optic nerve, the homogeneity index and conformity index of target areas, the time for dose recalculation and optimization were analyzed. Paired t test was used to analyze the obtained results, using 1 mm grid data as the reference. Results The paired t test on 2 mm grid and 1 mm grid showed that there was no statistical differences in OAR (P>0.05), except for PRV of the right lens, the right optic nerve and optic chiasm in group A (P<0.05) as well as the PRV of the right lens and optic chiasm in group B (P<0.05). No significant difference was found in OAR between 3 mm grid and 1 mm grid. There were statistical differences in groups A and B between 4 mm grid and 1 mm grid, except for the optic nerve and optic chiasm in groups A and B, and PRV of the right lens in group B. The paired t test on 5 mm grid and 1 mm grid showed that there were statistical differences in lens and lens PRV in groups A and B, and optic chiasm in group A, not in the optic nerve in groups A and B and optic chiasm in group B. There was no statistical difference in the dose parameters of OAR, and the CI and HI of target areas between group A (1 mm grid) and group B (1 mm grid). The time required in group B was 4 times longer than that in group A. Conclusion Compared with optic nerve and optic chiasm, lens and PRV of lens are more sensitive to computational grid size. For the accurate calculation as well as efficiency, using a grid size of 3 mm appears to be the most appropriate choice. For the clinical needs of 1 mm dose grid data, the plan can be firstly optimized by 3 mm grid and then recalculated using 1 mm grid.
Last Update: 2019-10-30