Spectral Analysis of X-Rays Scattered from Patients in Fluoroscopy

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Addis Ababa University


One of the main tasks in occupational radiation protection is the reliable determi~ nation of radiation protection dose quantities like effective dose or organ equivalent dose. Basic dosimetric quantities like air kerma or operational dose quantities like ambient dose equivalent, directional dose equivalent or personal dose equival~nt as measured by dosimeters provide only a rough approximation of the radiation protec~ tion quantities. To obtain a more detailed description of an exposure situation in terms of protective quantities the radiation field has to be analyzed with regard to its type, spectral energy distribution and direction of incidence to provide the necessary information for the conversion of operational quantities into protection quantities. In this work the spectroscopy of x~rays scattered by a patient. simulated by a wa~ tel' phantom, during fluoroscopic examination is investigated. The experiments are performed using a diagnostic x~ray unit. A spectrometer with a high~purity genna~ nium detector is operated in a highly collimated x-ray beam. An ionization chamber in the entrance field of the phantom serves as a monitor and provides reference values of the x-ray tube output. Scattered x-ray spectra are recorded for different tube voltages. spectrometerphantom distances and angular positions with respect to the direction of the inci~ dent x-rays. To validate the spectroscopic method, spectra of direct x-rays are also measured and compared with reference spectra



X-Rays Scattered from Patients