Validation of a model for estimating patient dose in computed radiography and application of diagnostic reference levels in direct radiography

The growing use of ionizing radiation in the medical field, due to its benefits in both diagnostic and therapeutic practices, has recently led to increased concern about the risks of exposure to such radiation on human health. As a result, it has arisen the need to regulate the medical use of ionizing radiation, as well as in other fields. To this end, Diagnostic Reference Levels (DRLs) have been introduced as a key tool for optimizing patient dose in medical imaging procedures. This thesis, carried out at the Operative Unit of Medical Physics of the IRCCS Azienda Ospedaliero-Universitaria di Bologna, focuses on DRLs for digital projectional radiography examinations of adult patients. The first part concerns an example of application of DRLs to the main radiographic procedures performed in an X-ray room at the IRCCS Azienda Ospedaliero-Universitaria di Bologna equipped with a Direct Radiography (DR) system, following the directives of the recent Legislative Decree n. 101/2020. All the procedures analyzed were found to comply with the national DRL values indicated in the ISTISAN report 20/22. The second part concerns the validation of a model for estimating the patient dose in some Computed Radiography (CR) examinations, proposed as a tool for verifying compliance with DRLs in such procedures. In fact, CR systems, unlike DR ones, do not provide information on the dose received by the patient, but only an indicator of the average exposure of the image receptor, i.e. the Exposure Index (EI) in the Carestream Health systems used in this thesis. For this reason, a model based on experimental dose measurements on uniform and anthropomorphic phantoms was constructed to evaluate the patient dose from the EI. The comparison between the model-derived patient dose and the one experimentally measured on the anthropomorphic phantom proved the correctness of the model. In addition, to be validated, the model was applied in another X-ray room obtaining consistent results.