Study of Four-Dimensional CT Combined with Cone-Beam CT on the Target Margin of Lung
Cancer Radiotherapy
HUANG Yan1, CAO Hongli1, PEI Xi2, WANG Zhi1
1. Department of Radiotherapy, The First Affiliated Hospital of Anhui Medical University, Hefei Anhui 230022, China;
2. Center of Radiological Physics, University of Science and Technology of China, Hefei Anhui 230022, China
Abstract：Objective To analyze the impacts on the external release value of target volume due to respiratory movement and setup
errors in radiation therapy for lung cancer with the help of four-dimensional computed tomography (4D-CT) combined with conebeam
CT (CBCT), to provide a reference for clinical target volume delineation. Methods A total of twenty-four lung cancer patients
who received 4D-CT scanning and radiation therapy from July 2020 to September 2022 in The First Affiliated Hospital of Anhui
Medical University were selected, among which twelve patients were treated with respiratory gating technique and twelve patients
were treated without respiratory gating technique. All patients underwent 4D-CT scanning during localization, and underwent CBCT
scanning before the first radiotherapy, and then underwent CBCT scanning weekly. Among them, patients treated with respiratory
gating underwent CBCT scanning before each treatment. The displacement of the tumor center at ten-time phases of the 4D-CT image
was used as the parameter affecting the respiratory movement, and the margin value of target volume was calculated in combination
with the displacement data of CBCT. Analyzed the position and setup errors of the tumor center point, as well as the correlation in
the three-dimensional direction of the tumor center point. Results In the 24 patients with respiratory movement, the displacement
of tumor center point in the directions of left-right, superior-inferior, and anterior-posterior were (0.21±0.20), (0.52±0.49) and
(0.29±0.21) cm, respectively. The displacement of setup errors in left-right, superior-inferior, and anterior-posterior directions were
(0.06±0.31), (-0.06±0.46) and (0.07±0.36) cm, respectively. Only by using the setup error, the external boundary value from
internal target volume to planning target volume can be obtained, and the maximum values in the three directions are 0.36, 0.47 and
0.43 cm, respectively. Using the displacement of the tumor center point and the displacement of the setup errors, the maximum values
of the three directions of the tumor target area were 0.73, 1.31, and 0.82 cm, respectively. Conclusion 4D-CT combined with CBCT
can reduce the target margin in the radiotherapy for lung cancer patients, and the use of respiratory gating based on 4D-CT plan can
also further accurately expand the target margin.
黄燕1，曹泓立1，裴曦2，汪志1. 4D-CT联合锥形束CT在肺癌放疗中
靶区外放边界的研究[J]. 中国医疗设备, 2023, 38(8): 32-37.
HUANG Yan1, CAO Hongli1, PEI Xi2, WANG Zhi1. Study of Four-Dimensional CT Combined with Cone-Beam CT on the Target Margin of Lung
Cancer Radiotherapy. China Medical Devices, 2023, 38(8): 32-37.
