Circularannular Tomography System Development

Initial studies were carried out with tissue-simulating phantoms using a single-source, single-detector system developed at the Hamilton Regional Cancer Center. This led to the successful demonstration of feasibility for NIR imaging in breast-tissue-like media [59, 60, 97-101]. An initial prototype single-channel system was developed at Dartmouth College in 1997 [102] (Figures 3 and 4). This system's success in imaging tissue phantoms led to the development of a first-generation clinical prototype that was tested in a pilot study involving a small group of women [103] including both normal subjects (to characterize variation between subjects) and a few women with characterized tumors. This first-generation system was adapted to feature an array of 32 optical fibers that could be translated radially in and out to accommodate different breast diameters and to facilitate breast positioning within the array. The second-generation array is shown in Figure 4.

We also developed a second-generation light delivery and acquisition system based on serial input of the source and simultaneous parallel detection at all receiver locations [104] (Figure 5). The number of wavelengths was increased to six, which permitted deconvolution not only of oxyhemoglobin and deoxyhemoglobin but also of tissue water fraction [105, 106]. These advances were key to improving the system's ability to accurately quantify the chromophores and scatterers which cause contrast in tumors. In addition, the newest system interface was designed to include three imaging layers, allowing capture of three cross-sections of light data in one setting.

Figure 3. Schematic of NIS tomography system using 16 source fibers (gray) and 16 detection fibers (black). Light from a single laser is launched into the source fibers by sequential alignment of the laser with each fiber using a translation stage. Detection is achieved by aligning a single detector with each fiber using a separate translation stage.

Figure 3. Schematic of NIS tomography system using 16 source fibers (gray) and 16 detection fibers (black). Light from a single laser is launched into the source fibers by sequential alignment of the laser with each fiber using a translation stage. Detection is achieved by aligning a single detector with each fiber using a separate translation stage.

0 0

Post a comment