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 and robustness of PTV-IMPT and ITV-IMPT plans were evaluated quantitatively.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 V 5Gy in normal 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), and normal 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.

Objective:To compare the safety and efficacy of the " step-up approach" versus the " step-jump approach" in treatment of infected pancreatic necrosis (IPN).Method:The clinical data of IPN patients who underwent step-up strategy or step-jump strategy treatment at the Department of Pancreatic and Biliary Surgery of the First Affiliated Hospital of Harbin Medical University from December 2018 to November 2022 were analyzed retrospectively. Propensity score matching (PSM) was done based on the nearest neighbor matching method (1: 1 ratio). After matching the baseline data (the caliper value was 0.01), a total of 62 patients with IPN were included, including 41 males and 21 females, aged (41.1±13.1) years old. Patients who were treated with the step-up strategy were included in the step-up group, while patients who were treated with the step-jump strategy were included in the step-jump group. There were 31 patients in each group after PSM, and the treatment effect of the two groups were compared.Results:Of the 62 patients with IPN, 43 received surgical intervention, and 19 were managed successfully using symptomatic anti-inflammatory treatment or percutaneous catheter drainage. The total hospitalization cost of patients in the step-jump group was significantly higher than that in the step-up group [122 000 (73 000, 179 000) yuan vs. 88 000 (46 000, 144 000) yuan, P=0.034]. The overall cure rate of IPN patients in the step-jump group was 93.5%(29/31). The 2 patients who died had type Ⅲ IPN. In the IPN patients in the step-up group were all cured, and the overall cure rate was 100%(31/31), with no death. There were no statistical differences between the two groups in the rates of death, postoperative complications, residual infection, debridement ≥2 times, and positive bacterial culture in blood or drainage fluid (all P>0.05). A total of 19.4% (12/62) patients had postoperative complications, including 4 patients with abdominal bleeding, 3 patients with new organ dysfunction, 2 patients with gastrointestinal bleeding, 2 patients with gastrointestinal fistula, and 1 patient with venous thrombosis in both lower limbs. Conclusion:Both the step-up treatment strategy and the step-jump treatment strategy were safe and effective for treatment of IPN patients.