Application of Styrofoam combined with head-neck-shoulder immobilization mask in calculating the expansion margins of target volumes and organs at risk for nasopharyngeal carcinoma
10.13491/j.issn.1004-714X.2025.05.023
- VernacularTitle:应用发泡胶联合头肩颈膜计算鼻咽癌靶区与危及器官外扩边界
- Author:
Zhiyong YANG
1
;
Jiping WANG
2
;
Guodong YANG
1
;
Wenkai LIU
1
;
Chengqiang ZHU
1
;
Kang TAN
3
Author Information
1. The Centre of Radiation Oncology, Huanggang Central Hospital of Yangtze University, Huanggang 438000, China.
2. The Centre of Radiation Oncology, Huanggang Central Hospital of Yangtze University, Huanggang 438000, China;Wuhan University of Science and Technology, Wuhan 430081, China.
3. Dept. of Radiation and Medical Oncology,Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
- Publication Type:OriginalArticles
- Keywords:
Styrofoam;
Nasopharyngeal carcinoma;
Planning target volume;
Planning organ at risk volume;
Setup error;
Expansion margin
- From:
Chinese Journal of Radiological Health
2025;34(5):770-775
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the expansion margins of the planning target volume (PTV) and the planning organ at risk volume (PRV) in nasopharyngeal carcinoma patients immobilized with Styrofoam and head-neck-shoulder mask. Methods A convenient sample of 33 nasopharyngeal carcinoma patients who received radiotherapy at Huanggang Central Hospital from January to October 2024 were selected as the research subjects. All patients underwent cone beam CT scans during the first three treatments and weekly thereafter. After registration and calibration, the setup errors in the X (LAT), Y (LNG), and Z (VRT) directions were recorded. Statistical analysis was performed on the setup errors in each direction to determine differences, and the expansion margins for PTV and PRV were calculated using empirical formulas. Results A total of 229 cone beam CT images were collected. Statistical analysis found that the setup errors (systematic error ± random error) of the patients in the X, Y, and Z directions were 1.05 ± 0.72, 1.30 ± 0.80, and 1.29 ± 0.82 mm, respectively. The expansion margins for PTV in the left-right, superior-inferior, and anterior-posterior directions were 1.40, 1.76, and 1.8 mm, respectively. The expansion margins for PRV in these directions were 0.83, 1.02, and 1.05 mm, respectively. Conclusion For patients immobilized using Styrofoam and head-neck-shoulder mask, it is recommended that the expansion margins for PTV and PRV be set at 2 mm and 1 mm, respectively, in the left-right, superior-inferior, and anterior-posterior directions, and the PRV margin for the spinal cord be set at 3 mm in all directions.
