Dosimetric Comparison of Different Fielding Schemes in Volumetric Rotational Intensity-
Modulated Radiotherapy for Nasopharyngeal Carcinoma
SHE Jin1, LI Lixin2, ZHANG Da3
1. Department of Medical Equipment, Yichang Central People’s Hospital, Yichang Hubei 443003, China;
2. Department of Radiotherapy, Sichuan Friendship Hospital, Chengdu Sichuang 610041, China;
3. Center of Radiation Therapy, Sichuan Cancer Hospital, Chengdu Sichuang 610058, China
Abstract：Objective To design double-arc coplanar (2F) plan, quadruple-arc coplanar (4F) plan and non-coplanar butterfly-shaped
field (BF) plan respectively of volumetric modulated arc therapy (VMAT) program for nasopharyngeal cancer, and compare the
dosimetric differences of different plans. Methods Ten patients with nasopharyngeal carcinoma were selected as the research
subjects, 2F, 4F and BF plans were designed respectively, and the differences of target area, organs at risk (OAR) and machine
parameters between 2F and 4F plans, 2F and BF plans were compared. Results In the target area, only the Dmax of target volume
(PGTV) in BF plan was significantly less than 2F (P<0.05), and other parameters of dosimetry had no significant difference (P>0.05).
The conformity index of 4F plan was higher than 2F (P<0.05) except for PGTV, while the BF plan was no significant different
compared with 2F. The homogeneity index of 4F plan was less than 2F (P<0.05) except for PCTV1, and only PCTV2 and PCTVln
of BF plan were less than 2F (P<0.05). The Dmax of spinal cord, the Dmean of left and right parotid glands as well as larynx of 4F plan
were significantly less than 2F (P<0.05). The Dmean of larynx of BF plan was significantly smaller than 2F (P<0.05), but the Dmax of
optic chiasm and left and right lenses were significantly higher than 2F (P<0.05). The machine units in 4F plan was significantly
higher than that of 2F plan (P<0.05). Conclusion All the three plans could satisfy the requirement of target dosimetry, but the BF
plan does not protect OAR better than the coplanar plan. The 4F plan can reduce the normal tissue spare while obtaining better dose
distribution, but it will increase the number of machine units.
佘瑾1，黎李鑫2，张达3. 鼻咽癌容积旋转调强放疗中不同布野方案的剂量学对比研究[J]. 中国医疗设备, 2022, 37(7): 31-34.
SHE Jin1, LI Lixin2, ZHANG Da3. Dosimetric Comparison of Different Fielding Schemes in Volumetric Rotational Intensity-
Modulated Radiotherapy for Nasopharyngeal Carcinoma. China Medical Devices, 2022, 37(7): 31-34.
