An investigation into the tertiary radiation contributions within an interventional radiology suite

This thesis aims to build on the current body of knowledge relating to the tertiary radiation contributions within an interventional radiology suite. An accurate estimation of tertiary radiation requires knowledge of the amount of patient-scattered radiation incident onto the concrete ceiling (the patient-scattered air kerma) and the fraction of the radiation incident on concrete that is scattered back towards the point of interest (the concrete-scattered air kerma). Evaluating the concrete-scattered air kerma incident on staff per unit Dose Area Product (DAP) incident on the patient, is near impossible during clinical use. Difficulties in measuring the concrete-scattered air kerma per unit DAP arise from the small fluence of X-rays emerging from the concrete ceiling along with the presence of the false ceiling and facilities typically mounted within the ceiling space (air conditioning ducting etc). These difficulties require that the tertiary radiation within an interventional suite be replicated experimentally. To this end, the X-ray spectra of patient-scattered radiation that would typically be incident on a concrete ceiling within an interventional suite was measured using an Amptek X-123 spectrometer. The X-ray spectra of a large number of primary X-ray beams (varying kVp and filtration) were also measured. The primary X-ray beams whose X-ray spectra most closely resembled that of the patient-scattered X-rays for a given scattering angle were identified and used as the source of X-rays incident onto a concrete block. These primary X-ray beams that replicated the patient-scattered X-rays enabled the measurement of X-rays scattered off a concrete block for a wide range of geometries and scenarios, subsequently allowing quantification of the concrete-scattered air kerma per unit DAP. Furthermore, the X-ray spectra of the concrete-scattered X-rays was also measured to gain further insight into the tertiary radiation contributions to interventional staff.<br> <br>For completeness, the patient-scattered air kerma present within an interventional suite under typical clinical conditions was also investigated experimentally. This investigation was undertaken to build upon existing literature which fails to account for relevant clinical aspects such as the patient support and variable X-ray tube angles incorporated within interventional procedures.<br><br>This thesis successfully provides improved knowledge of tertiary radiation within an interventional radiology suite. Empirical equations for the estimation of the patient-scattered air kerma per unit DAP as well as the concrete-scattered air kerma per unit DAP have been developed for typical clinical interventional conditions. The empirical equations developed allow for the accurate estimation of the tertiary radiation contributions to interventional staff. This work is not restricted by the assumptions and subsequent limitations made within the existing literature. In addition, the X-ray spectra scattered from the patient as well as that scattering from the concrete was measured. These findings will assist in the understanding of the characteristics of the patient-scattered and tertiary radiation within a clinical interventional suite.