Investigations of Staff Doses during Computed Tomography-Fluoroscopy Procedures Using Monte Carlo Simulation

Abstract

Radiation dose to staff during Computed Tomography (CT) fluoroscopy procedures has been investigated using Monte Carlo N-Particle code 6 (MCNP6). Four (4) CT machines located at Korle-bu Teaching Hospital, Sweden Ghana Medical Centre, Karlsruhe Hospital and FOCOS Orthopaedic Hospital respectively were modelled using SimpleGeo software. The patient (supine) and staff (standing) were represented both by Female Adult meSH (FASH) and Male Adult meSH (MASH) computational voxel phantoms. Seven scenarios consisting of staff use of protective equipment, CT gantry and staff positioning in the CT room, CT room size variation, the use of lead drape and patient cover on patient, the use of protective face mask and apron by staff, scatter radiation distribution in the CT room, and the effective estimation of staff effective dose were investigated for occupational staff protection. A systematic approach for validating CT scanners with unknown bowtie-filter was proposed and tested. The use of protective equipment, lead drape and patient cover, protective face mask and apron, diagonal positioning of CT fluoroscopy gantry, and staff standing away from walls of room were observed to reduce effective dose to staff by a factor of 4.5, 4.4, 2.8, 1.1 and 1.2 respectively. Sex based single and double TLD effective dose estimation algorithm was proposed. The staff dose reduction factors observed for applying protection measures for this study varied by a factor of 1.6 - 6.9 compared with other studies. The use of conventional protection equipment at all times is recommended and complemented with alternative one (that is, standing position) to further reduce doses.