Imaging elastographic contrast in optical coherence tomography for applications in dermatology and oncology

Skin cancer diagnosis often requires invasive biopsies. These can be time-consuming and cause discomfort to the patient. Optical coherence tomography is a non-invasive tool capable of imaging skin on the micron scale. However, the modality’s contrast sensitivity limits its ability to distinguish between healthy and diseased tissue in some non-melanoma skin cancers. In this thesis, optical coherence elastography is explored as a means of contrast enhancement through the analysis of a sample’s mechanical, rather than optical, properties. An analysis of OCT imaging performance is used to design a suitable elastography phantom. Experimental measurements are also used to optimise the image tracking software. A well-defined, controlled actuation is applied to a tissue phantom and imaged using optical coherence elastography. A stiff inclusion is subsequently discerned from the surrounding material, even though conventional image contrast is low. Elastographic detail is also depicted in tissue. Finally, enhancements in axial displacement sensitivity are acquired through the acquisition of phase data and alternative actuation techniques are explored. The optical coherence elastography technique was sensitive to a Young’s modulus ratio of 7 from a 56 μm actuation. The possibility of detecting smaller changes in mechanical properties was also investigated. Axial phase displacement sensitivity was 50 nm, with an order of magnitude increase in strain sensitivity. This demonstrates the technique’s potential usefulness in discriminating between cancerous and healthy tissues

Proposed Environmental Quality Standards for Phenol in Water

This is the Proposed Environmental Quality Standards (EQS) for Phenol in Water prepared for the National Rivers Authority, and published by the Environment Agency in 1995. The report reviews the properties and uses of phenol, its fate, behaviour and reported concentrations in the environment and critically assesses the available data on its toxicity and bioaccumulation. The information is used to derive EQSs for the protection of fresh and saltwater life and for the abstraction of water to potable supply. Phenol is widely used as a chemical intermediate and the main sources for phenol in the environment are of anthropogenic origin. Phenol may also be formed during natural decomposition of organic material. The persistence of phenol in the aquatic environment is low with biodegradation being the main degradation process (half-lives of hours to days). Phenol is moderately toxic to aquatic organisms and its potential to bioaccumulate in aquatic organisms is low

Assisted Probe Positioning for Ultrasound Guided Radiotherapy Using Image Sequence Classification

Effective transperineal ultrasound image guidance in prostate external beam radiotherapy requires consistent alignment between probe and prostate at each session during patient set-up. Probe placement and ultrasound image interpretation are manual tasks contingent upon operator skill, leading to interoperator uncertainties that degrade radiotherapy precision. We demonstrate a method for ensuring accurate probe placement through joint classification of images and probe position data. Using a multi-input multi-task algorithm, spatial coordinate data from an optically tracked ultrasound probe is combined with an image classifier using a recurrent neural network to generate two sets of predictions in real-time. The first set identifies relevant prostate anatomy visible in the field of view using the classes: outside prostate, prostate periphery, prostate centre. The second set recommends a probe angular adjustment to achieve alignment between the probe and prostate centre with the classes: move left, move right, stop. The algorithm was trained and tested on 9,743 clinical images from 61 treatment sessions across 32 patients. We evaluated classification accuracy against class labels derived from three experienced observers at 2/3 and 3/3 agreement thresholds. For images with unanimous consensus between observers, anatomical classification accuracy was 97.2% and probe adjustment accuracy was 94.9%. The algorithm identified optimal probe alignment within a mean (standard deviation) range of 3.7° (1.2°) from angle labels with full observer consensus, comparable to the 2.8° (2.6°) mean interobserver range. We propose such an algorithm could assist radiotherapy practitioners with limited experience of ultrasound image interpretation by providing effective real-time feedback during patient set-up

Voluntary versus ABC breath-hold in the context of VMAT for breast and locoregional lymph node radiotherapy including the internal mammary chain

Background: Deep-inspiration breath-hold (DIBH) reduces radiation dose to the heart in patients undergoing locoregional breast radiotherapy. In the context of tangential irradiation of the breast/ chest wall, a voluntary breath hold (vDIBH) technique has been shown to be as reproducible as a machine-assisted breath hold technique using the active breathing co-ordinator (ABCTM, Elekta, Crawley, UK, ABC_DIBH). This study compares set-up reproducibility for vDIBH versus ABC_DIBH in patients undergoing volumetric-modulated arc radiotherapy (VMAT) for breast cancer, both with and without wax bolus. Method: Patients with breast cancer requiring pan regional lymph node VMAT +/� wax bolus in breathhold were CT scanned in vDIBH and ABC_DIBH. Patients were randomised to receive one technique for fractions 1–7 and the other for fractions 8–15. Daily cone beam computed tomography (CBCT) was performed and registered to planning-CT using bony anatomy. Within-patient comparisons of mean daily chest wall position were made using a paired t-test. Population, systematic (P) and random errors (a) were estimated. Intrafraction reproducibility was assessed by comparing chest wall position and diaphragm movement between consecutive breath holds on CBCT. Results: 16 patients were recruited. All completed treatment with both techniques (9 patients with wax bolus, 7 patients without). CBCT derived P were 2.1–6.4 mm (ABC_DIBH) and 2.1–4.9 mm (vDIBH), a were 1.7–2.6 mm (ABC_DIBH) and 2.2–2.7 mm (vDIBH) and mean daily chest wall displacements (MD) were 0.0–1.5 mm (ABC_DIBH) and - 0.1–1.6 vDIBH (all p non-significant). Chest wall and diaphragm position was equivalent between consecutive breath holds in ABC and vDIBH (median difference 1.0 mm and 0.8 mm respectively, non p significant) demonstrating equivalent intrafraction reproducibility. Conclusion: This study demonstrates that a simple voluntary breath hold technique is feasible in combination with VMAT (+/� bolus) and is as reproducible as ABC_DIBH with VMAT for the irradiation of the breast and axillary and IMC lymph nodes in breast cancer patients

Improving 3D ultrasound prostate localisation in radiotherapy through increased automation of interfraction matching.

Background and purpose Daily image guidance is standard care for prostate radiotherapy. Innovations which improve the accuracy and efficiency of ultrasound guidance are needed, particularly with respect to reducing interobserver variation. This study explores automation tools for this purpose, demonstrated on the Elekta Clarity Autoscan®. The study was conducted as part of the Clarity-Pro trial (NCT02388308). Materials and methods Ultrasound scan volumes were collected from 32 patients. Prostate matches were performed using two proposed workflows and the results compared with Clarity's proprietary software. Gold standard matches derived from manually localised landmarks provided a reference. The two workflows incorporated a custom 3D image registration algorithm, which was benchmarked against a third-party application (Elastix). Results Significant reductions in match errors were reported from both workflows compared to standard protocol. Median (IQR) absolute errors in the left-right, anteroposterior and craniocaudal axes were lowest for the Manually Initiated workflow: 0.7(1.0) mm, 0.7(0.9) mm, 0.6(0.9) mm compared to 1.0(1.7) mm, 0.9(1.4) mm, 0.9(1.2) mm for Clarity. Median interobserver variation was ≪0.01 mm in all axes for both workflows compared to 2.2 mm, 1.7 mm, 1.5 mm for Clarity in left-right, anteroposterior and craniocaudal axes. Mean matching times was also reduced to 43 s from 152 s for Clarity. Inexperienced users of the proposed workflows attained better match precision than experienced users on Clarity. Conclusion Automated image registration with effective input and verification steps should increase the efficacy of interfraction ultrasound guidance compared to the current commercially available tools

London governance and the politics of neighbourhood planning: a case for investigation

The Localism Act 2011 has successfully devolved planning powers to over 2,500 English communities, involving 14 million people, with over 700 ‘made’ neighbourhood plans legitimised by referendum. In London, however, there are less than one-tenth of the made plans than in the rest of England. Institutional resistance and policy choices may be implicated. Two national studies of neighbourhood planning are reviewed. The role of the local authority is found to be a crucial factor in determining progress, and issues of social deprivation and unequal access are highlighted. Theorisation is considered by reference to a range of academic studies of localism and neighbourhood planning. Distinctions made between ‘representative’ and ‘community’ localism, and objections to anti-political effects, are noted. There has been remarkably little research into borough governance and neighbourhood planning in the capital. Based upon evidence of anomalous and differentiated governance practice, a study in London is called for

‘If independence goes, the planning system goes’: New Political Governance and the English Planning Inspectorate

Radical restructuring of 'arms-length' government bodies following the 2010 UK national election signalled a change in relations between government and the civil service. This was seen as a major shift in modes of governance from 'new public management' to a more politicised mode of 'new political governance'. This paper presents an analysis of the impacts of these shifts on the English Planning Inspectorate, an executive agency central to the land-use planning system. It identifies measures by ministers to increase control over the Inspectorate that represent a shift in governance culture and a shift in the planning system itself