A novel method of measuring the HU value of Varian carbon fiber Exact IGRT Couch and its clinical application
10.3969/j.issn.1005-202X.2025.09.002
- VernacularTitle:一种新型测量瓦里安碳纤维Exact IGRT Couch HU值的方法及临床应用
- Author:
Guangshan WANG
1
;
Tongmei ZHANG
;
Yan XING
;
Yiting NIU
;
Jianyue JIN
Author Information
1. 首都医科大学附属北京胸科医院放射治疗科,北京 101149
- Publication Type:Journal Article
- Keywords:
Exact IGRT Couch;
treatmen tcouch;
attenuation;
Hounsfield Unit value;
couch model
- From:
Chinese Journal of Medical Physics
2025;42(9):1130-1135
- CountryChina
- Language:Chinese
-
Abstract:
Objective To develop a novel method for measuring the Hounsfield Unit(HU)value of the surface carbon fiber material of the Varian Exact IGRT Couch,and to establish a treatment couch model in the treatment planning system(TPS)for correcting the attenuation of radiation dose caused by the treatment couch.Methods Two different field combinations were used to measure the radiation dose attenuation at the thin end and the middle medium-thickness part of the Varian Exact IGRT Couch.Dose deviations were measured when radiation passed through the treatment couch or not.Multiple sets of different HU values for the couch surface materials were defined in the TPS,and the dose difference between with and without couch was calculated under the same conditions as the measurements.The HU value of the treatment couch material corresponding to the actual measurements was found by data comparison and analysis.Results The attenuation for two interpenetrating fields was-2.49%to-1.69%at the thin end,and-3.43%to-2.23%at the medium-thickness part.The attenuation for multiple oblique incident fields ranged from-3.12%to-2.17%at the thin end,and that was-3.59%to-2.86%at the medium-thickness part.When the HU values of the couch model's surface and internal materials in the TPS were defined as-500 and-960,for two interpenetrating fields,the attenuation was-2.57%to-1.53%at the thin end,and-3.28%to-2.18%at the medium-thickness part;while for multiple oblique incident fields,the attenuation was-3.12%to-2.21%at the thin ends,and-3.42%to-2.43%at the medium-thickness part.These calculated results were consistent with the actual measurement values.For 40 verification plans,the average point dose difference between measurement and calculation in TPS were 0.90%and 0.89%at the thin end and medium-thickness part,respectively.Conclusion This novel measurement method can measure the HU value of the surface carbon fiber material and internal foam material of Exact IGRT Couch.Defining the HU values of these two materials of the couch model in the TPS as-500 and-960 can correct the radiation dose attenuation caused by the treatment couch,thereby improving the dose accuracy of the target volume and organs-at-risk.
