Multileaf collimators of two different leaf widths in radiotherapy of nasopharyngeal carcinoma: a dosimetric comparison(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2021年第3期
- Page:
- 302-307
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Multileaf collimators of two different leaf widths in radiotherapy of nasopharyngeal carcinoma: a dosimetric comparison
- Author(s):
- MA Tianbin; JIANG Zhendong; YU Haidong; ZHANG Hanxiong; HU Dan; CHEN Yibiao
- Department of Radiation Oncology, Meizhou Peoples Hospital (Huangtang Hospital), Meizhou 514031, China
- Keywords:
- Keywords: nasopharynx cancer multileaf collimator conformal index homogeneity index
- PACS:
- R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2021.03.006
- Abstract:
- Abstract: Objective To study the dosimetric differences between multileaf collimators (MLC) of different leaf widths (projected 0.5 cm leaf width and 1.0 cm leaf width at the isocenter) in intensity-modulated radiotherapy of nasopharyngeal carcinoma (NPC), and to explore the dosimetric effect of the leaf width of MLC on target areas and organs-at-risk. Methods The treatment plans of 31 randomly selected NPC cases in Meizhou Peoples Hospital (Huangtang Hospital) were re-optimized by accelerator beam models using MLC of different leaf widths under the condition of unchanged radiotherapy prescription and physical optimization parameters. The dosimetric parameters of target areas and main organs-at-risk, such as dose volume parameters, mean dose, conformity index and homogeneity index, were analyzed for discussing the dosimetric differences between 0.5 cm MLC and 1.0 cm MLC. Results The analysis of the whole sample showed that the homogeneity index of all target areas and the conformity index of some target areas (PGTVnx, PCTV2) in treatment plans using 0.5 cm MLC were better than those in treatment plans using 1.0 cm MLC, with statistical differences (P<0.05). No significant difference between 0.5 cm MLC and 1.0 cm MLC was found in the dosimetric parameters of organs-at-risk (P>0.05), except for some dosimetric parameters which were significantly lower in treatment plans using 0.5 cm MLC (P<0.05), including the maximum doses of right optic nerve and optic chiasm, the mean dose of left temporal lobe and right temporomandibular joint, the V30 of right and left parotid glands, and the mean dose of trachea and spinal cord. Similar results were obtained in both Pinnacle3 and Monaco planning systems, and there were statistically significant differences between 0.5 cm MLC and 1.0 cm MLC in target dose conformation and homogeneity, as well as dose delivered to some organs-at-risk (P<0.05). Conclusion In intensity-modulated radiotherapy of NPC, 0.5 cm MLC can effectively improve target dose conformation and homogeneity, and also can significantly reduce the dose delivered to some organs-at-risk, so as to better protect some organs-at-risk adjacent to or overlapping with target areas. Therefore, 0.5 cm MLC is recommended to be used in qualified hospitals.
Last Update: 2021-03-30