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Implementation of Routine Clinical Daily Dose Evaluation for Patient Specific Quality Control

K Brock

K Brock*, C Lee , C Lockhart , J Balter , R Ten Haken , A Eisbruch , University of Michigan, Ann Arbor, MI


SU-E-CAMPUS-J-2 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: The use of deformable registration and dose assessment in prospective clinical trials and routine patient quality control has been limited, largely due to lack of integration of the tools into standard clinical practice and decision support tools. A clinical workflow has been developed and implemented in a standard planning system using in room image.

Methods: A patient-specific quality control procedure has been initiated to ensure safe and accurate treatment delivery and develop decision making guidelines for future adaptation scenarios. Deformable registration, contour propagation, and dose calculation was performed in a clinical system (Varian, Eclipse v11). Twenty head and neck patients diagnosed with base of tongue cancer and treated with volumetric modulated arc therapy (VMAT) following daily kV-CBCT were evaluated. The planning CT was deformed to the daily CBCT to propagate the planning contours. Daily dose was calculated on the CBCT using a density calibration table and evaluated using the mapped contours. Deviations in the normal tissues were evaluated including the mean dose to the superior constrictors, left and right parotid glands (LPG, RPG), and left and right submandibular glands (LSG, RSG). The CTV D95 was also evaluated.

Results: Deformable registration and contour propagation was qualitatively evaluated and deemed acceptable for each fraction. The average (SD) daily fluctuation (planned-daily) in mean dose to the superior constrictor, LPG, RPG, LSG, and RSG was -3.0(6.0), 1.4(8.8), -1.1(10.7), 1.0(5.4), -2.0(8.5) cGy, respectively. The average (SD) daily fluctuation in D95 for the CTV was 3.7(3.8) cGy.

Conclusion: Daily dose assessment is feasible in a clinically available system. Data to guide adaptive decision making guidelines have been suggested, but require evaluation on additional patients for validity, which is ongoing. Dose accumulation, which is necessary for optimizing adaptive replanning, is needed within the clinical system to fully take advantage of this data.

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