Carbon ion radiotherapy planning: a study of prescription dose conversion between microdosimetric kinetic model and local effect model
10.3760/cma.j.cn113030-20231007-00112
- VernacularTitle:碳离子放射治疗计划中MKM和LEM模型的处方剂量转换研究
- Author:
Zijie ZUO
1
;
Zhiqiang LIU
;
Qinghua ZHANG
;
Xu HAN
;
Tianqi DU
;
Hongtao LUO
;
Shilong SUN
;
Yu ZHANG
;
Qiuning ZHANG
;
Xiaohu WANG
Author Information
1. 中国科学院近代物理研究所，兰州 730000
- Publication Type:Journal Article
- Keywords:
Radiotherapy, carbon ion;
Microdosimetric kinetic model;
Local effect model;
Prostatic neoplasms;
Chordoma
- From:
Chinese Journal of Radiation Oncology
2025;34(2):151-159
- CountryChina
- Language:Chinese
-
Abstract:
Objective:In carbon ion treatment planning of water phantom, establish a conversion factor calculation system and conversion factor curves for organs at risk (OAR) for microdosimetric kinetic models (MKM) and local effect models (LEM), and validate them in clinical patient planning.Methods:Using a uniform spherical water phantom as the research object, relative biological effectiveness-weighted doses (RWD) for the LEM were re-calculated based on the physical dose of RayStation-MKM. The median dose within the planning target volume (PTV) of LEM and MKM was regarded as the conversion factor. The impacts of single-fraction target prescription dose, spread-out Bragg peak (SOBP) width and depth, shape, and irradiation mode on the conversion factor were assessed, and a conversion factor calculation system was established. Additionally, the accuracy of the conversion factor calculation system was validated using both water phantoms and clinical patient cases. The conversion factor curves for OAR were computed based on clinical patient treatment plans.Results:The primary influencing factors for the conversion factors were the single-fraction prescription dose, target SOBP width and depth. The conversion factors were increased with the increase of SOBP width and target depth, whereas decreased with the increase of the single-fraction prescription dose. Under single-field irradiation, a conversion factor calculation system was established based on above 3 parameters. For the plans of 9 patients, the average difference between the calculated results and the conversion factor calculation system was 0.340% ± 0.203%, and the average difference in the conversion curves for OAR was 2.650% ± 2.399%.Conclusion:A dose conversion factor calculation system and conversion factor curves for OAR for carbon ion radiotherapy are established for MKM and LEM, and their accuracy meets the requirements for use in clinical patient treatment plans.
