Influence of CT Value-Electron Density Conversion Curve on VMAT Planning Dose Calculation
ZHOU Jun, LU Aiqiong, HE Shui, KE Zhenqi, WANG Haiyi
Department of Oncology and Hematology, Meishan Hospital Affiliated to Chengdu University of Traditional Chinese Medicine/
Meishan Traditional Chinese Medicine Hospital, Meishan Sichuan 620010, China
Abstract：Objective To analyze the influence of CT value-electron density conversion curve on volumetric modulated arc therapy
(VMAT) plan dose calculation. Methods A total of nine CT value-electron density conversion curves (H_100, H_120, H_140,
C_100, C_120, C_140, A_100, A_120, A_140) of different tube voltages, tube currents and scanning sites were collected and
established. Taking H_120 condition of head scan sequence as standard scanning condition, dose calculation was performed on the
same VMAT radiotherapy plan for nasopharyngeal carcinoma, respectively. The VMAT plan was transplanted to the verification
phantom, the dose calculation was performed, the verification plan was created, and the dose difference between standard and nonstandard
conditions was analyzed. Results The dose comparison between the standard condition and the non-standard condition of
the VMAT plan showed that the dose error of brainstem was the largest, Dmax error was 26.90 cGy, and the relative error was 0.52%.
There was no statistically significant difference in dosimetry between the abdominal condition A_140 (abdominal 140 kV 300 mA)
and the standard condition (P>0.05). There were statistically significant differences in dosimetry between other conditions and
standard conditions (P<0.05). Compared with the standard condition and non-standard condition dose of the phantom verification
plan, the Dmean error of the dense bone was the largest, which was 0.30 cGy, and the relative error was 0.56%. The statistical analysis
results showed that there were statistically significant differences between the non-standard condition and the standard condition dose
of the phantom verification radiotherapy plan (P<0.05). Conclusion Different CT value-electron density conversion curves have a
certain influence on the dose calculation of VMAT plan. In clinical work, it is necessary to establish a standard CT value-electron
density conversion curve for different tube voltages, tube currents, scanning sites, etc. During CT simulation and dose calculation,
CT simulation localization and dose calculation, the corresponding scanning parameter conditions and CT value-electron density
conversion curve should be selected to improve the accuracy of dose calculation.
周军，卢爱琼，何水，柯珍奇，王海屹. CT值-电子密度转换曲线对VMAT
计划剂量计算的影响[J]. 中国医疗设备, 2023, 38(8): 26-31.
ZHOU Jun, LU Aiqiong, HE Shui, KE Zhenqi, WANG Haiyi. Influence of CT Value-Electron Density Conversion Curve on VMAT Planning Dose Calculation. China Medical Devices, 2023, 38(8): 26-31.
