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  • br Finally the new planning target volume and standard plann

    2019-10-14


    Finally, the “new” planning target volume and standard planning target volume were compared and analysed by an inde-pendent samples T test.
    2.5. “New” plan and standard RTOG 0848 plan generation for adjuvant radiotherapy
    2.5.1. Volumetric modulated arc therapy plan
    We applied the “new” target PTV-90 edited and standard tar-get PTV edited to create “new” and standard plans, respectively, in the above five simulated patients using volumetric modulated arc therapy techniques by EclipseTM 13.5 TPS software. The determi-nation of organs at risk, dose–volume constraints and prescription doses for all plans were all based on the RTOG 0848 protocol. Organs at risk included the liver, stomach, left kidney, right kidney, small intestine and spinal cord, of which the kidneys, liver and stomach should be delineated entirely but the renal hilum was excluded, and
    Fig. 1. Pancreatic cancer local recurrence map. (a): Anterior-posterior view; (b): lateral view. Digitally reconstructed radiographs showing local recurrences with respect to the celiac artery (orange) and the superior mesenteric artery (magenta) for patients with resected primary pancreatic head (red) and body (green) cancer.
    the small intestine from the LY 379268 to 2 cm below the lowest slice of the CTV was delineated. Furthermore, we decided to only con-tour the spinal cord within the cranial–caudal extent of the PTV. The dose–volume constraints for organs at risk are shown in Table 2. The “new” and standard plans both included delivery of 5040 cGy in 180 cGy fractions to the PTV-90 H edited and PTV edited, respectively, for 5 consecutive days weekly. To ensure consistency of all plans, more than 95% of the target volume received at least 95% of the prescription dose, and no more than 1 cm3 of PTV-90 H edited and PTV edited received 107% of the prescription dose. All the volumet-ric modulated arc therapy plans employed two arcs with angles of 100◦ to 260◦ counter clockwise and 260◦ to 100◦ clockwise, respec-tively, and 6MV X-rays at a dose rate of 600 monitor units (MU) per minute were adopted. The “new” plans and standard plans were evaluated by comparing the planning parameters, the dose distribution of the target volumes, and organs at risk utilizing the dose–volume histogram.
    2.6. Statistical analysis
    IBM SPSS Statistics 21.0 and Excel software were used for data calculations and statistical analyses of all data, and the results were expressed as the mean or mean ± standard deviation.
    3. Results
    3.1. Three-dimensional local recurrence map
    The three-dimensional local recurrence map is shown in Fig. 1, in which the red dots and green dots in the template image represent the location of local recurrences for the postoperative patients with pancreatic head cancer and pancreatic body cancer, respectively. In general, most of the recurrences were distributed around the celiac artery and the superior mesenteric artery. Thirteen patients (27%) developed recurrences closer to the celiac artery, with a mean and standard deviation of the distance to the celiac artery of 2.20 ± 0.97 cm, and the average distance for patients with pan-creatic head cancer and pancreatic body cancer were 2.47 cm and 1.88 cm, respectively, in this group. Thirty-five patients developed recurrences closer to the superior mesenteric artery, with a mean and standard deviation of the distance to the superior mesenteric artery of 2.32 ± 1.04 cm, and the average distance for patients pan-creatic head cancer and pancreatic body were 2.17 cm and 2.60 cm, respectively.
    The standard abdominal width and thickness of the template patient were 28.03 cm and 20.16 cm, respectively. The results of the