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Biomedical subjects

C Baldock

Publications and source records attributed to C Baldock.

64 records · Page 4Linked to original sources
PubMed1994

3-D reconstruction of an ancient Egyptian mummy using X-ray computer tomography.

Computer tomography has been used to image and reconstruct in 3-D an Egyptian mummy from the collection of the British Museum. This study of Tjentmutengebtiu, a priestess from the 22nd dynasty (945-715 BC) revealed invaluable information of a scientific, Egyptological and palaeopathological nature without mutilation and destruction of the painted cartonnage case or linen wrappings. Precise details on the removal of the brain through the nasal cavity and the viscera from the abdominal cavity were obtained. The nature and composition of the false eyes were investigated. The detailed analysis of the teeth provided a much closer approximation of age at death. The identification of materials used for the various amulets including that of the figures placed in the viscera was graphically demonstrated using this technique.

Humans↗
PubMed1993

Radiation risks to personnel and public during the treatment of malignant glioma using interstitial brachytherapy.

125I seeds are used in brachytherapy for the treatment of malignant gliomas. The use of such radioactive sources is associated with a certain radiological hazard to both personnel and members of the public. This hazard should be quantified so that the ALARA principle of radiological protection may be implemented satisfactorily. A study was undertaken to derive isodose rate contours in the vicinity of an anthropomorphic phantom with 125I seeds positioned at typical tumour sites within the cranial cavity. These contours are illustrated for seed positions appropriate to deep and superficial temporal tumours. Results indicate that the annual doses to personnel and public should not exceed those recommended by the International Commission on Radiological Protection.

Air Pollutants, Radioactive↗
PubMed1992

Radiation dose to patients and staff from Storz Modulith SL20 lithotripter.

Extracorporeal shock wave lithotripsy (ESWL) uses either X-ray fluoroscopy or ultrasound to localize and determine the end point of treatment. We report radiation doses to patients and personnel from the Storz Modulith lithotripter system recently installed in the Lithotripter Centre, St. Thomas' Hospital, London. The mean annual radiation dose to patients and staff was calculated at 0.73 mSv and 4.8 mSv, respectively.

Humans↗
PubMed1991

Analysis of sample volume dependence of 125I in a radionuclide calibrator.

Results are presented showing the volume dependence of the measured activity of 125I in Capintec radionuclide calibrators. Errors of up to 76% were encountered for commonly used syringes and vials when the manufacturer's calibration factor was used. Calibration factors have been determined for syringes and vials which reduce errors to less than 2%.

Calibration↗
PubMed1991

Field comparison of the interferon-gamma assay and the intradermal tuberculin test for the diagnosis of bovine tuberculosis.

An extensive field comparison of the gamma interferon (IFN-gamma) assay and the single intradermal tuberculin test for the diagnosis of bovine tuberculosis was conducted in Australia. The specificity of the IFN-gamma assay was determined by testing more than 6000 cattle from tuberculosis-free herds and varied from 96.2% to 98.1%, depending on the cut-off point chosen to define a positive reactor. For the sensitivity trial, cattle from herds being de-populated because of bovine tuberculosis were examined with both assays. The sensitivity of the IFN-gamma assay was shown to be significantly higher than the single intradermal tuberculin test and varied from 76.8% to 93.6% depending on the method of interpretation. A maximum overall sensitivity of 95.2% was obtained by testing with the IFN-gamma and the tuberculin test in parallel. The superior sensitivity of the IFN-gamma assay and the ability to adjust the sensitivity of the system depending on the task involved, will provide the Australian Tuberculosis Eradication Campaign with a valuable additional test to enable it to accomplish its goals.

Animals↗
PubMedDate not supplied

Three-dimensional reconstructions of extracellular matrix polymers using automated electron tomography.

The extracellular matrix is an intricate network of macromolecules which provides support for cells and a framework for tissues. The detailed structure and organisation of most matrix polymers is poorly understood. These polymers have a complex ultrastructure, and it has proved a major challenge both to define their structural organisation and to relate this to their biological function. However, new approaches using automated electron tomography are beginning to reveal important insights into the molecular assembly and structural organisation of two of the most abundant polymer systems in the extracellular matrix. We have generated three-dimensional reconstructions of collagen fibrils from bovine cornea and fibrillin microfibrils from ciliary zonules. Analysis of these data has provided new insights into the organisation and function of these large macromolecular assemblies.

Animals↗
PubMedDate not supplied

Measuring facial swelling using three-dimensional imaging.

Requirements exist clinically for quantitative analysis of facial swelling. A quick and non-invasive measurement of facial volume is desirable. The acquisition of three-dimensional images, corresponding to spatial models of patients' facial surfaces, has been facilitated using a Spatial Vision System (SVS) developed by Thorn EMI Central Research Laboratories (UK). The SVS acquires four video images (two step pairs) and constructs a three-dimensional surface representation using stereo matching of spatial features acquired using 'speckled' illumination. Pre- and post-operative binary volumetric images are then spatially aligned using surface matching algorithms. Accuracy of registration is optimized using Match Volume Excavation. Segmentation of post-operative swelling is achieved by volume differencing in combination with morphological erosion. Volumetric quantification is achieved using a method of three-dimensional region growing, giving the number of connected voxels in the image volume from a user selected seed point. Accuracy of image acquisition has ben quantified by imaging a range of hemispherical phantoms of known volumes. The mean error in repeated measurement of volume was found to be within 3.5%. The perception of temporal changes in facial swelling is highly subjective. Further work is being undertaken to develop and Enhanced Reality visualization tool in which graphical swelling annotations are combined with real-time patient images.

Computer Simulation↗