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Objective:To investigate the factors affecting the accuracy of electronic portal imaging device (EPID)-based in vivo dose verification in radiotherapy for patients with lung and esophageal cancers, and to recommend the workflow and specifications for the application of the in vivo dose verification. Methods:This study randomly selected 32 patients who received radiotherapy for esophageal and lung cancers at the Department of Radiation Oncology, Jinhua Municipal Central Hospital from May to August 2022, including 14 lung cancer cases and 18 esophageal cancer cases. Using a uRT-linac 506c linear accelerator, these patients were treated according to the dynamic intensity-modulated radiotherapy (dIMRT) and EPID-based In vivo dose verification ( In vivo EPID) plans developed with the uRT-TPOIS planning system. The In vivo dose verification performed during the treatment included 238 fractions of In vivo EPID and 80 fractions of image-guided radiotherapy (IGRT) for the lung cancer cases, as well as 414 fractions of In vivo EPID and 105 fractions of IGRT for the esophageal cancer cases. The 2D γ passing rate for each irradiation field was obtained according to the set threshold value. Furthermore, fractioned irradiation fields with γ-passing rates below the threshold value were analyzed, and primary factors decreasing the γ-passing rate were further analyzed by combining the online CT images and 3D reconstruction-derived dose. Results:For lung and esophageal cancers, the mean γ-passing rates were 95.1% ± 5.7% and 96.5% ± 4.5%, respectively at 3 mm/5%; 91.5% ± 8.4% and 92.2% ± 4.9%, respectively at 3 mm/3%, and 79.1% ± 14.7% and 83.7% ± 8.2%, respectively at 2 mm/2%, indicating no statistically significant differences between two cancers ( P > 0.05). The average γ passing rate for beam orientations near 0°/180° (Group A) was higher than those near 90°/270° (Group B) 3 mm/5%: Z = -25.4, P < 0.05; 3 mm/3%: Z = -26.8, P < 0.05). The IGRT correction of setup errors significantly improved the γ passing rates (96.3% ± 5.1% and 96.4% ± 4.9%, respectively at 3 mm/5%, Z = -5.50, P < 0.05; 92.3% ± 8.0% and 91.3% ± 7.7%, respectively at 3 mm/3%, Z = -9.54, P < 0.05). The results of In vivo dose verification were affected by changes in the volumes and motion of tumors and normal tissues, radiotherapy positioning, and adequacy of pre-treatment preparation. Conclusions:EPID-based In vivo dose verification during radiotherapy can avoid incorrect irradiation. However, it is necessary to standardize the workflow of the EPID-based In vivo dose verification to avoid the decrease in the γ passing rate caused by artificial factors.
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OBJECTIVE To observe the ther apeutic efficacy and safety of albumin-bound paclitaxel combined with oxaliplatin in the first-line treatment of advanced gastric cancer （GC）. METHODS A total of 90 advanced unresectable GC patients were randomized into observation group and control group ，with 45 patients in each group. Control group was given oxaliplatin combined with tegafur ，and observation group was given albumin-bound paclitaxel combined with oxaliplatin. A chemotherapy cycle last for 21 days，and both groups received 6 cycles of chemotherapy ，and then the follow-up observation was conducted every 2 weeks. Short-term efficacy （after 2 chemotherapy cycles ），mid-term efficacy （after 6 chemotherapy cycles ），tumor marker，long-term efficacy （after follow-up ），quality of life ，the occurrence of ADRs were compared between 2 groups. RESULTS After 2 cycles of treatment ，objective remission rate （ORR）of observation group was significantly higher than that of control group （60.00％ vs. 37.78％，P＜0.05）；there was no statistical significance in disease control rate between the two groups （P＞0.05）. After 6 chemotherapy cycles ，ORR of observation group was significantly higher than that of control group （55.56％ vs. 31.11％，P＜0.05）；there was no statistical significance in disease control rate between the two groups （P＞0.05）；the levels of tumor markers [carcinoembryonic antigen ， carbohydrate antigen （CA）724， CA199， CA242] in observation group were significantly lower than those of control group （P＜0.05）. After the follow-up period ，the median progression-free survival [ 8.78 （95％CI：6.94-11.01）months] and the median overall survival [ 13.02（95％CI：12.78-15.62）months] of observation group were significantly longer than those [ 6.99（95％CI：3.67-10.88）months and 10.42（95％CI：8.72-13.22）months] of control group （P＜ 0.05）. The score of body dimension in the observation group was significantly higher than that in the control group （P＜0.05）. Except for peripheral neurotoxicity ，there was no significant difference in the incidence of ADR between 2 groups（P＞0.05）. CONCLUSIONS Albumin-bound paclitaxel combined with oxaliplatin has a good effect and safety in the first-line treatment of advanced unresectable GC.