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Title: The use of tomography images in the XRF measurement of platinum in tumours following chemotherapy
Author: Ghara'ati, H.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1994
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The technique of X-ray fluorescence of heavy elements is widely used in medical physics and has been used for tracing the platinum-based drugs administered for the treatment of malignant tumours. A method is developed for analyzing an in vivo XRF system and optimizing the system for measuring the absorption of platinum in the target. The nature of the emitted radiation and its interaction with materials are explained. The general principles of the Monte Carlo method are described. A flexible program for an annular source/collimator and back-scattering geometry is developed. Several techniques are employed to improve the statistics and the program calculates the XRF spectrum for several heavy elements simultaneously. The dimensions and shielding materials of the source collimator are investigated in detail. The results support the choice of tungsten with a thin lining of tin or copper. The background spectrum contains a prominent Compton peak, the region above this containing mainly singly-scattered photons and the region below mainly multiply-scattered photons (plus the target element K-line). Very few of these multiply-scattered photons originate in the phantom, and the high background observed experimentally in the low-energy region is therefore attributed to scattering on the surface of the detector collimator. A design is proposed which would reduce this scattering considerably. A matrix of detection sensitivity versus depth and radius of the field is obtained. To calculate the response due to the tumour one can integrate the sensitivity over the volume of the tumour using data obtainable from tomographic images (like CT or MRI). It is also found that the regions of producing the greatest number of K-photons are not directly visible from the detector. A design is proposed which corrects for this deficiency and should therefore greatly improve the detection limit.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available