Detection of Photoacoustic Transients Originating from Microstructures in Optically Diffuse Media such as Biological Tissue

The generation and detection of broadband photoacoustic (PA) transients may be used for on-axis monitoring or for imaging of optically different structures in the interior of diffuse bodies such as biological tissue. Various piezoelectric sensors are characterized and compared in terms of sensitivity, depth response, and directivity with respect to spherical broadband acoustic pulses. The influence on the sensor output of acoustic interference and refraction of the PA transients at the sample-sensor interface is discussed. Ring detectors are suitable for deep on-axis detection thanks to their strong directional sensitivity, and small disk sensors are most suited for 3-D imaging of microstructures such as the (micro)vascular system. Voltage and charge preamplification schemes are compared in terms of the signal-to-noise ratio (SNR). In all cases, the preamplifier noise turns out to be the limiting factor for the sensitivity. Based on experimental data, for several sensor types and optical wavelengths, the theoretical detectability of PA signals generated by blood-like absorbers in biological tissue is discusse

Treatment of pain following cancer : applying neuro-immunology in rehabilitation practice

Aim: Pain is the second most frequent persistent symptom following cancer treatment. This article aims at explaining how the implementation of contemporary pain neuroscience can benefit rehabilitation for adults following cancer treatment within an evidence-based perspective. Materials and methods: Narrative review. Results: First, pain education is an effective but underused strategy for treating cancer related pain. Second, our neuro-immunological understanding of how stress can influence pain highlights the importance of integrating stress management into the rehabilitation approach for patients having cancer-related pain. The latter is supported by studies that have examined the effectiveness of various stress management programmes in this population. Third, poor sleep is common and linked to pain in patients following cancer treatment. Sleep deprivation results in a low-grade inflammatory response and consequent increased sensitivity to pain. Cognitive behavioural therapy for sleep difficulties, stress management and exercise therapy improves sleep in patients following cancer treatment. Finally, exercise therapy is effective for decreasing pain in patients following cancer treatment, and may even decrease pain-related side effects of hormone treatments commonly used in cancer survivors. Conclusions: Neuro-immunology has increased our understanding of pain and can benefit conservative pain treatment for adults following cancer treatment

Photoacoustic tomography system for noninvasive real-time three-dimensional imaging of epilepsy

A real-time three-dimensional (3D) photoacoustic imaging system was developed for epilepsy imaging in small animals. The system is based on a spherical array containing 192 transducers with a 5 MHz central frequency. The signals from the 192 transducers are amplified by 16 homemade preamplifier boards with 26 dB and multiplexed into a 64 channel data acquisition system. It can record a complete set of 3D data at a frame rate of 3.3 f/s, and the spatial resolution is about 0.2 mm. Phantom experiments were conducted to demonstrate the high imaging quality and real time imaging ability of the system. Finally, we tested the system on an acute epilepsy rat model, and the induced seizure focus was successfully detected using this system