Program Information
Site Specific Image-Guided Radiotherapy (IGRT) Tolerances for Patient Safety
K Wijesooriya*, K Seitter , I Dharia , P Read , J Larner , University of Virginia Health Systems, Charlottesville, VA
Presentations
SU-E-T-703 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:
To present our single institution experience of a very large pool of data, for all treatment sites, with image-guided radiotherapy, comparing patient’s external tattoo marks, kV or MV orthogonals to align to bony anatomy, and CBCT for soft tissue registration of the tumor volumes. To present measurement based tolerances for daily imaging registration shifts that could be used as guidelines.
Methods:
From March 2013 to March 2014, 17197 patient treatment fields were analyzed for the treatment of brain, chest-wall, esophagus, head and neck, lung, pelvis, prostate, spine, extremities, and breast. TrueBeam trajectory log files for all imaging types as well as all treatment types were accessed, and couch parameters compared. Three types of shifts are evaluated: i) kV, or MV orthogonal imaging shifts from patient’s tattoo marks to bony anatomy surrounding the tumor, ii) CBCT imaging shifts from patients bony alignment to soft tissue alignment of tumor, iii) CBCT imaging shifts from patients tattoo marks to soft tissue alignment of tumor. Shifts in the anterior-posterior (AP), superior-inferior (SI), and left-right (LR) dimensions were recorded. Site specific mean and standard deviation of absolute differences were also compared.
Results:
Site specific observed imaging tolerances are: brain (1.82 cm), chest-wall (1.26 cm), esophagus (1.60 cm), head and neck (1.2 cm), lung (1.97 cm), pelvis (3.65 cm), prostate (2.64 cm), spine (1.38 cm), extremities (3.96 cm).
Conclusion:
These site specific imaging tolerances could be used as guidelines for raising a red flag when exceeded.
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