title: Assessment of patient dose reduction by bismuth shielding in CT using measurements, GEANT4 and MCNPX simulations.
abstract: This work reports on the use of two different Monte Carlo codes (GEANT4 and MCNPX) for assessing the dose reduction using bismuth shields in computer tomography (CT) procedures in order to protect radiosensitive organs such as eye lens, thyroid and breast. Measurements were performed using head and body PMMA phantoms and an ionisation chamber placed in five different positions of the phantom. Simulations were performed to estimate Computed Tomography Dose Index values using GEANT4 and MCNPX. The relative differences between measurements and simulations were <10 %. The dose reduction arising from the use of bismuth shielding ranges from 2 to 45 %, depending on the position of the bismuth shield. The percentage of dose reduction was more significant for the area covered by the bismuth shielding (36 % for eye lens, 39 % for thyroid and 45 % for breast shields).
authors: Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal monicamendes@ctn.ist.utl.pt.
authors: M
authors: M
authors: Mendes
authors: Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
authors: F
authors: F
authors: Costa
authors: Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
authors: C
authors: C
authors: Figueira
authors: Serviço de Radiologia, Hospital de São José, Centro Hospitalar Lisboa Central, EPE, Rua José António Serrano, 1150-199 Lisboa, Portugal.
authors: P
authors: P
authors: Madeira
authors: Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
authors: P
authors: P
authors: Teles
authors: Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Estrada Nacional 10 (km 139,7), 2695-066 Bobadela LRS, Portugal.
authors: P
authors: P
authors: Vaz
mesh_terms: D000465:Algorithms; D001729:Bismuth; D001940:Breast / Q000528:radiation effects; D003198:Computer Simulation; D003201:Computers; D004867:Equipment Design; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000528:radiation effects; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011482:Protective Devices; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D013961:Thyroid Gland / Q000528:radiation effects; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods
chemical_list: D001729:Bismuth