Planning target volume-Is it still suitable for intensity modulated proton therapy for lung cancer?
Shang Haijiao1, Pu Yuehu1, Chen Zhiling1, Shen Liren1, He Xiaodong2, Huang Xiaoyan3, Wang Yuenan4
1Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China; 2Department of Radiation oncology, Ruijin Hospital Affiliated to the Shanghai Jiao Tong University, Shanghai 200025, China; 3Sun Yat-sen University Cancer Center, Cancer Hospital of Sun Yat-sen University, Guangzhou 510060, China; 4Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen 518116, China
Abstract：Objective To demonstrate the concept of planning target volume (PTV) is not suitable for intensity proton therapy (IMPT) in lung cancer, plan differences were compared based on the concept of PTV and Internal target volume (ITV), aiming to provide clinical reference.Methods Six patients were retrospectively selected and approved by the local ethics committee. Each of the six patients received two IMPT plans based on a synchronous accelerator model,developed by SINAP team (Shanghai Institute of Applied Physics, China Academy Science University) and commercial treatment system:one with the PTV-based robust IMPT (PTV-IMPT) plan and the other with ITV-based robust IMPT (ITV-IMPT) plan. Three beams were set in all plans, and the final dose was calculated using Monte Carlo dose algorithm. The plan quality androbustnessof PTV-IMPT and ITV-IMPT plans were evaluatedquantitatively. Results Compared to the PTV-IMPT plan, ITV-IMPT plan showed better target conformity index (conformability index:0.58 vs.0.43),better homogeneity index (homogeneity index:0.96 vs.0.92), lower V5Gy innormal lung tissue(13.1% vs.13.5%) and maximum dose in spinal cord (8.9 Gy vs. 9.5 Gy) as well as plan monitor unit (MU:338 vs. 401) . In addition, ITV-IMPT plan showed more robust in target coverage (0.003-0.032 vs. 0.02-0.28), andnormal lung tissue was also found a bit robust in the ITV-IMPT plan(0.06-0.11,0.07-0.13). Conclusions Compared with the PTV-IMPT plan, ITV-IMPT plan has the advantages of high planning quality, well robustness and better tumor motion mitigation. Therefore, ITV concept is recommended to be applied in the IMPT plan for lung cancer.
Shang Haijiao,Pu Yuehu,Chen Zhiling et al. Planning target volume-Is it still suitable for intensity modulated proton therapy for lung cancer?[J]. Chinese Journal of Radiation Oncology, 2020, 29(7): 540-545.
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