Investigating the Validity of Soft Tissue Signs on Lateral Ankle X-Ray to Aid Diagnosis of Achilles Tendon Rupture in the Emergency Department

AimsTo investigate the diagnostic validity of four radiological soft tissue signs Kager's sign (K), disruption to the tendon (D), loss of parallelism (P) and fusiform swelling of the tendon (F) on a lateral ankle x-ray to aid Achilles tendon rupture diagnosis.MethodsWe retrospectively identified two groups of patients; Group A consisted of patients with an Achilles tendon rupture and Group B included patients with a clinically intact Achilles tendon but with a lateral ankle ligament sprain. Three clinicians independently reviewed all patients' x-rays for each of the radiological features under investigation to determine whether a rupture was present or not. Inter-rater and Intra-rater reliability were calculated using the Kappa coefficient (Kc.) To determine the predicted value of the signs sensitivity, specificity, positive predicted values and negative predicted values were calculated.Results85 patients x-rays were included in this study; Group A n = 47, Group B n = 38. The most valid radiological sign appeared to be loss of parallelism (sensitivity 70%, specificity 97%, kappa 0.55-0.58).ConclusionClinicians reviewing a lateral ankle x-ray of a patient with an acute ankle injury should review the x-ray for loss of parallelism between the tendon and skin; identification of this radiological sign may alert the clinician to the possible diagnosis of a ruptured Achilles tendon. Reviewing this may reduce the number of missed Achilles ruptures

Physical modelling of electroporation in close cell-to-cell proximity environments

Many applications of electroporation, especially those utilizing electrofusion and in-vivo electroporation, involve cell environments that include close cell-to-cell proximity and a wide range of target cell size. It is important to understand how this kind of environment may alter optimum electroporation electrical parameters for any given application. A physical, electrically equivalent model of biological cell electroporation, based on aqueous solution filled thin latex rubber membrane spheroids, was used to investigate membrane permeabilization behaviour where there is both close cell-to-cell proximity and different cell radii. Cell model arrangements were pulsed using either a 50 µs or 10 µs, 1/e decay time constant dc capacitive discharge electric field, with peak amplitudes of 160-500 kV m⁻¹. Results indicate that, compared to cells in isolation, electroporation initiates at substantially decreased applied electric field magnitudes in regions of close cell-to-cell proximity where the external media conductivity is lower than the cell interior conductivity, and the membrane is maximally polarized. Additionally, the use of shorter time constant, higher peak magnitude pulse parameters should reduce the relative difference in threshold membrane permeabilization in regions of close cell-to-cell proximity for cells of different size so that the degree of electroporation is more uniform for variable size and shape target cell populations

Volcanic Ash Contamination of High Voltage Insulators

Awarded Best Paper (Student) - Joint Winner - EEA Conference 2011Recent work in the University of Canterbury high voltage laboratory uncovered an interesting phenomenon. While studying the effect of volcanic ash contamination on high voltage insulator flashover levels, ash was seen ‘blowing’ off the insulator surface before flashover occurred. The goal of this project was to investigate and explain the observed phenomenon to provide a basis for potential development of self-cleaning insulators. Four different types of insulator and three different ash grain sizes were tested. The insulator electric fields were modelled; corona discharge waveforms and visual observations were obtained. Areas of ash removal coincided with areas of corona discharge. It was initially proposed that the ash was removed by an alternating current corona wind however the results do not support this theory. Instead, the observed results suggest that the ash acquires a negative charge and is removed by an electrostatic force. The electrostatic force is strongest during the negative half cycle of the applied voltage due to space charge and hence the ash pulses off the insulator at 50Hz. The amount of ash removed increased with the applied voltage however this led to a trade off between ash removal and flashover. The maximum amount of ash removed during this project was approximately 90% from the top weather shed and 30% from the middle and bottom weather sheds. This study focused on the removal of dry ash. It is unlikely that wet ash can be removed in this fashion, without flashover, due to the conductive and adhesive nature of wet ash

Comparative Dosimetric Analysis and Normal Tissue Complication Probability Modelling of Four-Dimensional Computed Tomography Planning Scans Within the UK NeoSCOPE Trial

Neoadjuvant chemoradiotherapy for resectable oesophageal cancer improves overall survival compared to surgery alone but is associated with increased toxicity. NeoSCOPE is a trial of two different nCRT regimens for resectable oesophageal and was the first multi-centre trial in the UK to incorporate 4D-CT into the radiotherapy planning. Using NeoSCOPE 4D-CT cases, we undertook a dosimetric comparison study of 3D-CT versus 4D-CT plans comparing target volume coverage and dose to organs at risk. We used established normal tissue complication probability (NTCP) models to evaluate the potential toxicity reduction of using 4D-CT plans in oesophageal cancer. Our work shows that incorporating 4D-CT into treatment planning may significantly reduce the toxicity burden from this treatment