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In dynamic contrast-enhanced dedicated breast computed tomography (DCE-bCT), functional insights in the breast will potentially be assessed by evaluating the iodine contrast uptake and washout over time. This information is expected to be relevant for breast cancer treatment. However, the image-based quantitative estimates of iodine concentration (mg I/ml) at each time point will need to be validated. To achieve this, we are developing an in-line optical absorption spectroscopy setup that enables real-time iodine concentration monitoring in a dynamic breast phantom. Potassium iodide was used as the contrast agent. First, the relationship between the iodine concentration (0.5 to 7.6mg I/ml) and light absorption was evaluated in a laboratory UV-VIS spectrophotometer (200 to 1000nm). Thereafter, an in-line spectroscopy setup was built including a light source to illuminate the contrast, a light filter (521 to 543nm), and a photodetector to capture the transmitted light. The system’s precision was tested on nine different iodine concentrations (0.5 to 7.6mg I/ml). The detectability of an iodine profile and applicability of the setup in combination with a DCE-bCT phantom was evaluated. The UV-VIS spectrophotometer showed a linear relationship between light absorption and iodine concentrations at wavelengths between 500 to 650nm. The in-line spectroscopy setup showed a coefficient of variation of 0.29%. In combination with a dynamic breast phantom, time-varying iodine profiles could be detected quantitatively, with the injection time matching wash-in and wash-out visible in the transmission curves. The developed in-line absorption spectroscopy setup can quantify time-varying iodine concentrations and shows potential to be a tool for the validation of DCE-bCT imaging.
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