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SU‐E‐T‐527: Comparison of CT‐On‐Rails and a 3D Surface Imaging System for Image Guided Partial Breast Radiation Therapy
Author(s) -
Zhao H,
Wang B,
RassiahSzegedi P,
Huang Y,
Sarkar V,
Szegedi M,
Sadinski M,
Kokeny K,
Poppe M,
Salter B
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612480
Subject(s) - medicine , radiation therapy , medical imaging , nuclear medicine , cone beam computed tomography , radiology , computed tomography
Purpose: We evaluate the feasibility of using a 3D surface imaging system (AlignRT) for image guidance for partial breast radiation treatments through comparison with the CT‐on‐rails image guidance currently clinically employed at our institution. Methods/Materials: Four patients receiving external beam partial breast radiation therapy with multiple image guidance datasets were analyzed retrospectively. A total of 51 fractions were studied, each with a CT‐on‐rails dataset and an AlignRT body surface contour snapshot. For each fraction, the patient was aligned to treatment isocenter with room lasers and scanned with both CT‐on‐rails and AlignRT. Image guidance shifts were calculated for both modalities by comparison to the simulation CT and the differences between the two sets of shifts were analyzed. Results: Two patients showed significant change in surgical cavity volume and shape between simulation and fraction 1. For these patients it was found that the discrepancy between CT‐on‐rails based shifts and AlignRT shifts was significant (up to 11.1 mm) indicating that use of AlignRT for image guidance of these cases would be inadvisable. The remaining two patients did not show noticeable change in surgical cavity and the discrepancy between the two sets of shifts for these patients was minimal, thus indicating that AlignRT is potentially valuable for these cases. Conclusion: AlignRT appears to be a reasonable and potentially valuable image guidance approach for partial breast radiation therapy for patients with small changes in surgical cavity between CT simulation and treatment. However, there may be potential for alignment inaccuracies when using AlignRT for patients with dramatic changes in surgical cavity.