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Dose Calculation Variations in AAA and Acuros-XB for Pancreatic Cancer Treatment Planning

K Harpool

K Harpool*, E Schnell , T Herman , S Ahmad , T De La Fuente Herman , Oklahoma Univ. Health Science Ctr., Oklahoma City, OK


SU-I-GPD-T-427 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To investigate quantitatively the variations in dose distributions calculated by the anisotropic analytical algorithm (AAA) and Acuros-XB algorithm in the treatment of pancreatic cancer patients.

Methods: CT images from twelve pancreatic cancer patients were used to generate VMAT treatment plans with the Eclipse treatment planning system and the dose distributions were calculated using two dose calculation algorithms: AAA and Acuros-XB with heterogeneity on. The plans used two arc fields, and the photon energy was 6 MV. The prescription dose was 4950 cGy in 18 fractions. Plans were compared quantitatively based on Conformity Index (CI), dosimetric parameters of normal tissues (kidneys, liver, spinal cord, and bowel) utilizing QUANTEC guidelines and the results were statistically compared with student’s two-tail t-test where p-value < 0.05 is considered significant.

Results: The average mean and maximum doses to the total kidney calculated with Acuros XB were lowered by 0.67% (p=0.76) and 1.14% (p=0.77), respectively compared to that calculated by AAA. The dose to a third of the liver volume (V1/3) and mean dose to the liver from Acuros XB plans were lowered by 6.22% (p=0.01) and 1.64% (p=0.09), respectively compared to corresponding AAA calculations. The maximum dose to the bowel was reduced with Acuros XB by 4.60% (p=0.45). The maximum dose to the spinal cord was higher by 3.93% (p=0.03) with Acuros XB compared to that with AAA. The CI for both AAA and Acuros XB calculations was 1.15 (p<0.41).

Conclusion: The dose distributions to the critical normal structures surrounding the Planned Target Volume (PTV) calculated with the Acuros-XB were comparable to the corresponding distributions calculated by AAA while maintaining the same dose conformity of the PTV.

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