Monte Carlo Investigation into Scatter Radiation from CT Fluoroscopy Gantry: Effect on Staff Dose. A Contribution to Occupational Radiation Protection in Medicine

Investigation into scatter radiation from CT fluoroscopy gantry using Monte Carlo N-Particle eXtended (MCNPX) has been done. Using already proven method of modelling point source, bowtiefilter and collimator, the CT compartment of the PET-CT equipment at Karlsruhe Klinikum was modelled. Additions to the model were CT gantry block, patient table, CT room, standing and supine Male Adult meSH (MASH) phantom. Varying the gantry block material with air, zinc, iron, tungsten, aluminium, magnesium, barium, tin, gadolinium oxysulfide, caesium iodide and xenon, the scatter radiation at the isocenter of the CT and to the medical staff was investigated. Scatter radiation from the gantry block had an influence on measurements with inonisation chamber at the isocenter. Radiation exposure to the eye lens and thyroid of medical staff was independent of the presence of a gantry block or material. The whole body exposure of medical staff was however dependent on the presence of a gantry block but independent of gantry block material of zinc or tin. (author)