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Modified Dynamic-Conformal-Arc Study for Multiple Anatomic Sites at Standard Dose Fractionation

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R Foster

R Foster1*, H Parks2 , M Xu3 , M Pankuch4 , M Stutz5 , (1) Northwestern Medicine Chicago Proton Center, Warrenville, IL, (2) Northwestern Medicine Cancer Center Delnor, Geneva, IL, (3) CDH Proton Center, Geneva, IL, (4) CDH Proton Center, Warrenville, IL, (5) Radiation Oncology Consultants, Geneva, IL


SU-I-GPD-T-404 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: To evaluate the effects on dose conformity and DVH distributions in plans generated on the Eclipse treatment planning system v11 (TPS) using modified Dynamic-Conformal Arc (MDCA) technique.

Methods: The MDCA technique was applied to clinical simulation images sets on patients with various anatomic target sites including abdomen, lung, esophagus, and pelvis nodes. The MDCA plans included methods of preferentially blocking a local OAR. Additional plans using standard, static 3-D conformal radiotherapy (3DCRT) and Volumetric Modulated Arc Therapy (VMAT) methods were designed for comparisons. PTV and OAR values with respect to maximum dose, mean dose, and prescription coverage using each technique were evaluated in addition to total treatment planning time and treatment delivery time.

Results: The MDCA plan was superior for certain cases compared to 3DCRT plan in coverage of PTV. The MDCA had clinically similar plan quality compared to VMAT to the referring physicians for mean dose, hot spots, and DVH evaluation. The MDCA, as compared to the VMAT plan, showed half cases with lower hot spots, and same mean dose with one case lower, comparable shoulder and tail for DVH and PTV coverage. Compared to the VMAT, the MDCA planning time was reduced by a factor of 3 – 4 because optimization was not needed, in which TPS automatically made PTV conformable and OAR avoidable. An average delivered MU in the MDCA was only 10% higher than the 3DCRT, but 47% lower than the VMAT.

Conclusion: The MDCA technique offers a practical alternative to 3DCRT and VMAT in the ongoing effort to optimize plan quality, treatment delivery, and workflow efficiency in the cases studied. The MDCA was a simplified planning and delivery technique that meets the requirement for PTV coverage, OAR’s avoidance while reducing planning time, beam-on time, and total MU.

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