Volumetric Modulated Arc Therapy for Bilateral Breast Carcinoma: Dosimetric Analysis and Immediate Tolerance

Abstract

blocks, which could open the way to improved CTV definition and planning. Materials/Methods: An in-house, spectral domain OCT system was developed for this study. A pair of tilting galvanometer mirrors permits lateral scanning of the infrared beam resulting in a 5x5x3-mm image volume. Paraffin blocks (40x25x4 mm) containing formalin-fixed mouse mammary glands with tumor were imaged. Other than removing the plastic mount, the blocks were not manipulated in any way in preparation for imaging. After each scan, the blockswere translated on amoveable stage until the entire samplewas imaged. Blocks were scanned through both sides in order to image their full thickness. Individual scans were stitched together to generate a final, complete image volume. For comparison, sections at multiple depths were obtained from the blocks, stained with hematoxylin and eosin (H&E), and photographed at high magnification and resolution. Results: Complete 3D images of the tissue blocks were obtained. The scan time for a single 5x5x3-mm image was about 15 seconds. A lateral resolution of 16 mm and a 6-mm resolution in the depth direction permitted visualization of tissue micro-architecture that correlated with the H&E section images. Images from consecutive blocks could be stitched together, allowing reconstruction of larger specimens over multiple blocks. Because of the paraffin medium, both micro-CT and small animal MRI were unable to visualize any features within the blocks. Conclusions: Optical coherence tomography is a fast, non-invasive, highresolution imaging modality capable of volumetric reconstruction of paraffin tissue blocks. As such, it could greatly facilitate the imaging and analysis of microscopic disease needed to study and improve CTV design and treatment. Author Disclosure: L. Kim: None. R. Droz-Rosario: None. E. Hwuang: None. L. Higgins: None. M. Pierce: None.