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Tomography is a powerful tool for reconstructing the interior of an object from a series of projection images. Typically, the source and detector traverse a standard path (e.g., circular, helical). Recently, various techniques have emerged that use more complex acquisition geometries. Current software packages require significant handwork, or lack the flexibility to handle such geometries. Therefore, software is needed that can concisely represent, visualize, and compute reconstructions of complex acquisition geometries. We present tomosipo, a Python package that provides these capabilities in a concise and intuitive way. Case studies demonstrate the power and flexibility of tomosipo.

We acquired images of breast malignancies using the Twente photoacoustic mammoscope (PAM), to obtain more information about the clinical feasibility and limitations of photoacoustic mammography. Results were compared with conventional imaging and histopathology. Ten technically acceptable measurements on patients with malignancies and two measurements on patients with cysts were performed. In the reconstructed volumes of all ten malignant lesions, a confined region with high contrast with respect to the background could be seen. In all malignant cases, the PA contrast of the abnormality was higher than the contrast on x-ray mammography. The PA contrast appeared to be independent of the mammographically estimated breast density and was absent in the case of cysts. Technological improvements to the instrument and further studies on less suspicious lesions are planned to further investigate the potential of PAM.

We present the Twente Optical Perfusion Camera (TOPCam), a novel laser Doppler Perfusion Imager based on CMOS technology. The tissue under investigation is illuminated and the resulting dynamic speckle pattern is recorded with a high speed CMOS camera. Based on an overall analysis of the signal-to-noise ratio of CMOS cameras, we have selected the camera which best fits our requirements. We applied a pixel-by-pixel noise correction to minimize the influence of noise in the perfusion images. We can achieve a frame rate of 0.2 fps for a perfusion image of 128x128 pixels (imaged tissue area of 7x7 cm2) if the data is analyzed online. If the analysis of the data is performed offline, we can achieve a frame rate of 26 fps for a duration of 3.9 seconds. By reducing the imaging size to 128x16 pixels, this frame rate can be achieved for up to half a minute. We show the fast imaging capabilities of the system in order of increasing perfusion frame rate. First the increase of skin perfusion after application of capsicum cream, and the perfusion during an occlusion-reperfusion procedure at the fastest frame rate allowed with online analysis is shown. With the highest frame rate allowed with offline analysis, the skin perfusion revealing the heart beat and the perfusion during an occlusion-reperfusion procedure is presented. Hence we have achieved video rate laser Doppler perfusion imaging.

A theoretical model is presented and experimentally validated that allows the prediction of the effect of speckles on the depth sensitivity of laser Doppler perfusion imaging. It is shown that the influence of speckles on depth sensitivity is large. In particular the sensitivity to particle motion in superficial layers is strongly beam diameter dependent: decreasing the beam diameter on the tissue surface increases the sensitivity to superficial motion to a much stronger extent than sensitivity to motion at a larger depth. This can be explained through the effect of beam diameter changes on the fractional coherence areas generated by photons with different penetration depths in the tissue.

From calibrated, weakly scattering tissue phantoms (2-6 mm-1), we extract the attenuation coefficient with an accuracy of 0.8 mm-1 from OCT data in the clinically relevant 'fixed focus' geometry. The data are analyzed using a single scattering model and a recently developed description of the confocal point spread function (PSF). We verify the validity of the single scattering model by a quantitative comparison with a multiple scattering model, and validate the use of the PSF on the calibrated samples. Implementation of this model for existing OCT systems will be straightforward. Localized quantitative measurement of the attenuation coefficient of different tissues can significantly improve the clinical value of OCT.