ABSTRACT
[Abstact] Objective To analyze the related parameters of the treatment plans for the pancreatic cancer with the Cyber-knife system.Methods The clinical data of 129 patients with single-target pancreatic cancer for the first time who underwent CyberkKnife radiosurgery between January 2017 and December 2017 in Shanghai Changhai Hospital were retrospectively analyzed.The parameters were all selected from the MultiPlan @4.0.2 treatment planning system and the data were analyzed.Results The volume of the targets in 129 patients with pancreatic cancer was 3.355-238.936 cm3,with the average volume of 51.43 ± 55.64 cm3.Patients were averagely treated for 5 to 8 sessions,and the average prescription dose was 6 Gy × 6 fraction,which equaled to 58 Gy in the biological equivalent dose (BED).The collimators with 20 mm and 15 mm accounted for up to 31％ and 27％,respectively,which were the top 2 options.The finally designed the conformal index(CI),new conformal index(nCI),and the homogeneity index were 1.14 ± 0.09,1.29 ± 0.09 and 1.42 ± 0.04,respectively.The coverages of tumor target was 80.3％-95.6％,with the average of 90.0 ± 4.6％.The treatment nodes,beams and Mus are 79,180 and 7 060 in average.The estimated treatment time was 42 ± 8 minutes.The organs at risk can be protected very well.Conclusions Reasonable Cyber-knife treatment plan can guarantee that stereotactic body radiation therapy can effectively treat Pancreatic Cancer.
ABSTRACT
Objective To propose the method of dose distribution calculated by one-step optimization with 7 shells (Cao method) and compare with that by three-step optimization with 4 shells (Blanck method) and CyberKnife treatment plans for pancreatic cancer. Methods 20 cases of pancreatic cancer who underwent CyberKnife treatment were retrospectively analyzed,and CT was performed to localize and delineate the target area and endangering organs. Dosage was optimized and evaluated with Blanck method and Cao method. The planning target volume (PTV) conformity index (CI), new conformity index (nCI), homogeneity index (HI),gradient index (GI), coverage, dose-volume and doses to organs at risk were compared. Results Compared with Blanck method, CI (1.11 ± 0.05 vs 1.15 ± 0.05), nCI (1.20 ± 0.06 vs 1.23 ± 0.06), coverage [(92.48 ± 1.85)% vs (93.53 ± 2.15)%], volumes encompassed by 100% and 30% prescription dose line (36.46 ± 16.64 vs 38.19 ± 17.68; 286.19 ± 126.52 vs 320.93 ± 154.82) and monitor unit (56 369 ± 20 019 vs 57 814 ± 20 531) were significantly decreased,while GI was increased (3.22 ± 0.19 vs 3.11 ± 0.19), and all the differences were statistically significant (P<0.05). Additionally, Dmax of the intestine (21.17 ± 2.90 vs 20.63 ± 3.13), D10cc of the stomach (12.78 ± 2.57 vs 13.11 ± 2.43), D5ccof the duodenum (11.01 ± 3.45 vs 11.50 ± 3.25), D10ccof the duodenum (9.30 ± 3.31 vs 9.78 ± 3.07) and D0.35ccof the spinal cord (6.09 ± 0.98 vs 6.59 ± 0.92) were all significantly decreased (P<0.05). No significant differences were found on other parameters. Conclusions Better dose distributions are accessible by one-step optimization with 7 shells in CyberKnife treatment plans for pancreatic cancer.