Heating has been known to cure cancer for over 2000 years1, and recent studies have confirmed this in the treatment of basal cell carcinomas (BCC)2. The application of uncontrolled heating often results in unacceptable scarring. Our ability to control the delivery of heat using a forward-looking infrared (FLIR) camera and a modulated long pulsed (LP) Nd:YAG 1064nm laser has resulted in better outcomes in comparison to traditional destruction techniques3. Use of optical coherence tomography (OCT) enhances our ability to define the tumor margins prior to treatment. The combination of FLIR and OCT allows very precise treatment of BCCs with at least comparable outcomes to conventional LP Nd:YAG treatments.
Optical coherence tomography (OCT) was introduced as an imaging system, but like ultrasonography, other measures, such as blood perfusion and polarization of light, have enabled the technology to approach clinical utility. This review aims at providing an overview of the advances in clinical research based on the improving technical aspects. OCT provides cross-sectional and en face images down to skin depths of 0.4 to 2.00 mm with optical resolution of 3 to 15 μm. Dynamic optical coherence tomography (D-OCT) enables the visualization of cutaneous microvasculature via detection of rapid changes in the interferometric signal of blood flow. Nonmelanoma skin cancer (NMSC) is the most comprehensively investigated topic, resulting in improved descriptions of morphological features and diagnostic criteria. A refined scoring system for diagnosing NMSC, taking findings from conventional and D-OCT into account, is warranted. OCT diagnosis of melanoma is hampered by the resolution and the optical properties of melanin. D-OCT may be of value in diseases characterized with dynamic changes in the vasculature of the skin and the addition of functional measures is strongly encouraged. In conclusion, OCT in dermatology is still an emerging technology that has great potential for improving further in the future.
Optical coherence tomography (OCT) allows non-invasive imaging of sub-surface structures in vivo, ideally without a
need for target preparation. In conventional OCT, the contrast for blood vessels depends on a variety of factors and can
be challenging. Speckle variance has been recognized as a method to enhance contrast for blood flow without the
application of contrast agents in OCT images.
Here, we demonstrate the possibility of extracting blood flow information from a volumetric OCT datasets that was
obtained routinely from a human participant. We used a commercially available OCT system with a clinical CE-mark.
The light source has a central wavelength of 1310 nm. Using Multi-Beam technology, the system achieves an isometric
resolution of better than 7.5 μm in tissue over the entire imaging depth of around 1 mm. At 1 mm image width, 21
frames (B-scans) per second can be imaged.
We used the speckle variance in order to enhance the contrast for blood vessels in vivo. This method allowed us
determining the presence and depth of blood flow within the 1 mm penetration depth, without dependence on direction
or orientation of the blood flow with respect to the scanning beam.
At BIOS08, the authors presented a novel multi-beam Optical Coherence Tomography (OCT) system that overcomes the problem of limited lateral resolution inherent in single-beam Fourier Domain OCT. We now present image processing algorithms for blending the images from each OCT beam, producing a seamless composite image, and show how the use of multiple beams can produce additional benefits, including speckle noise reduction, leading to improved clinical detail in the results.
The lateral resolution of Fourier domain optical coherence tomography (FD-OCT) systems is limited by the depth of focus that can be achieved over the desired imaging depth at the chosen wavelength. I present a solution in which multiple beams focused at different depths are scanned together, so that a mosaic image can be produced, with at least double the resolution possible from a single beam system. Side-benefits also arise from the ability to combine data from
each beam to improve signal-to-noise. The theory of this approach is discussed, advantages, and also the practical realisation in a variety of ex-vivo and in-vivo OCT imaging probes, together with results from a number of applications.
The lateral resolution of Fourier domain optical coherence tomography (FD-OCT)
systems is limited by the depth of focus that can be achieved over the desired imaging
depth at the chosen wavelength. Various solutions have been proposed such as Bessel
beams and computational methods; however these suffer from various practical
drawbacks. We present a novel optical set-up involving multiple optical channels that
does not suffer from these drawbacks and delivers at least double the resolution of a
single beam system. The theory of this approach is discussed, also the realisation in a
practical laboratory system, measurement results and initial application in assessing
oesophageal cancers and pre-cancers.
The Durham University Centre for Advanced Instrumentation (formerly the Astronomical Instrumentation Group) has been involved in the development of both research and facility class astronomical adaptive optics systems and their associated control systems for over 20 years. The centre also has interests in commercial and non-astronomical research AO systems, including the areas of novel wavefront correctors and AO control systems. Firstly this paper summarises Durham's history in AO control, then we seek to provide an overview of why the group is moving to FPGA technology for control systems in the context of new work. We then present a collaboration between Sira Technologies Ltd. and Durham, aimed at exploiting FPGA technology to provide high speed, low cost AO control for commercial applications, we examine the results so far achieved, and finally we present our Integrated Wavefront Sensor product concept.
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