SU-E-T-279: Dose Enhancement Effect Due to Cerium Oxide Nanoparticles Employed as Radiation Protectants
- Univ Massachusetts Lowell, Lowell, MA (United States)
Purpose: The goal of radiotherapy is to maximize radiation dose to diseased cells while minimizing radiation damage to normal tissues. In order to minimize damage to normal tissues, cerium oxide nanoparticles (nanoceria) are currently considered as a radioprotectant. However, some studies have reported concerns that nanoceria can also lead to radiotherapy dose enhancement due to the high atomic number of cerium, especially when used in conjunction with kV energy and brachytherapy sources. In this study, this concern is investigated to determine if the concentrations of nanoceria employed in in-vivo studies to confer radioprotection can engender a significant dose enhancement. Methods: Radiation with energies ranging from 50kVp to 140kVp is investigated in this work along with brachytherapy sources Pd-103 and I-125. A previously established theoretical model is used to calculate the dose enhancement factor (DEF). In this model, each cell is assumed to be a voxel of size (10 µm, 10 µm, 10 µm) with nanoceria homogeneously distributed among them. Electron energy loss formula of Cole is used to calculate energy (and hence dose) deposited by photoelectrons and Auger electrons in each tissue voxel due to irradiation of nanoceria. The DEF is defined as the ratio of the dose with and without nanoparticles. Results: DEF calculation results are smaller than 1.02 with dosages of nanoceria smaller than 0.645 mg/g, which is shown to be sufficiently protective by some previous in-vitro and in-vivo experiments. The brachytherapy sources show higher DEF’s than kVp radiations. DEF peaks are consistent with K shell and L shell energies of cerium, 40 keV and 6 keV, respectively. Conclusion: The results show that for sufficiently radioprotective concentrations of nanoceria, there will be minimal DEF when used in conjunction with clinically applicable kV energy radiotherapy sources or brachytherapy sources.
- OSTI ID:
- 22548336
- Journal Information:
- Medical Physics, Journal Name: Medical Physics Journal Issue: 6 Vol. 42; ISSN 0094-2405; ISSN MPHYA6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
61 RADIATION PROTECTION AND DOSIMETRY
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ABUNDANCE
ANIMAL TISSUES
ATOMIC NUMBER
BIOLOGICAL RADIATION EFFECTS
BRACHYTHERAPY
CERIUM OXIDES
CONCENTRATION RATIO
ENERGY LOSSES
IN VITRO
IN VIVO
IODINE 125
IRRADIATION
K SHELL
L SHELL
NANOPARTICLES
PALLADIUM 103
RADIATION DOSES