Study on robustness of two kinds of IMRT plans on fixed field of whole brain and whole spinal cord of pediatric patients
10.3969/j.issn.1672-8270.2025.08.009
- VernacularTitle:儿童全脑全脊髓两种固定野调强放射治疗计划的稳健性研究
- Author:
Yuejian HE
1
;
Weichen LI
;
Guanhua DENG
;
Maoying LAN
Author Information
1. 中山大学附属第六医院放疗科 广州 510655;广州市黄埔区中六生物医学创新研究院 广州 510700
- Publication Type:Journal Article
- Keywords:
Radiotherapy for whole brain and whole spinal cord;
Intensity-modulated radiotherapy(IMRT)on fixed field;
Overlapping method;
Gradient optimization method;
Stability
- From:
China Medical Equipment
2025;22(8):46-51
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the sensitivity of intensity-modulated radiotherapy(IMRT)designed respectively by overlapping method and gradient optimization method on fixed field of whole brain and whole spinal cord of pediatric patients to positioning error.Methods:A retrospective study analyzed 10 pediatric patients who underwent radiotherapy on whole brain and whole spinal cord at The First Affiliated Hospital of Guangzhou Medical University during December 1,2022 and January 1,2024.Overlapping method and gradient optimization method were respectively adopted to design IMRT plan for whole brain and whole spinal cord.The length of the merged region of the field was set as 10 cm.The positioning errors of±1 mm,±3 mm and±5 mm on head-foot direction that occurred in spinal cord segmentation and other isocenter field were simulated,and the flux optimization did not be conducted,and the dose distribution was recalculated.The exposure doses of D2%,D98%,V30Gy,homogeneity index(HI),conformity index(CI)and organ at risk(OAR)of target regions in the merged region of field were recorded and compared,thus the robustness of the two optimization methods were assessed.Results:The IMRT plan of whole brain and whole spinal cord that were designed respectively by overlapping method and gradient optimization method can meet the clinical requirements under the condition that did not introduced positioning error.With the increasing of positioning error,the changes of cold and hot spots(ΔD2%,ΔD98%and ΔV30 Gy)of doses in the merged region of field were more and more significant.In the merged region of field,theΔD2%,ΔD98%and ΔV30 Gy of the overlapping method were respectively 13.98%±3.29%,-17.26%±3.44%and-44.06%±9.17%,and those of the gradient optimization method were respectively 6.0%±0.75%,-6.31%±0.81%and-37.37%±4.3%when positioning error was 5 mm.The differences of them between the overlapping method and the gradient optimization method were statistically significant(t=-10.889,15.928,2.808,P<0.05).Conclusion:With increase of positioning error in the merged region of field of IMRT plan for whole brain and whole spinal cord,the gradient optimization method can effectively relieve the changes of the cold and hot spots in the merged region of field,and its each indicator was less than that of the overlapping method.Therefore,it can effectively improve the plan's robustness.
