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Optimization of aluminum thickness for absorption of undesired Ti K X-rays in the measurement of low energy brachytherapy source strength
The contribution of Ti K X-rays to total air kerma strength for low energy brachytherapy sources ( 125I and 103Pd) are calculated for different source-to-aperture distances of an indigenously designed free air ionization chamber. For 30 cm source-to-aperture distance, calculated contribution of Ti K...
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Published in: | Annals of nuclear energy 2011-02, Vol.38 (2), p.632-636 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The contribution of Ti K X-rays to total air kerma strength for low energy brachytherapy sources (
125I and
103Pd) are calculated for different source-to-aperture distances of an indigenously designed free air ionization chamber. For 30
cm source-to-aperture distance, calculated contribution of Ti K X-rays is 4%. The Ti K X-rays can be eliminated by a relatively thin aluminum filter, but the primary photons emitted by the source will also be attenuated. This effect should be compensated by applying a suitable correction factor. The uncertainty in the attenuation correction factor has been also calculated for different thicknesses of aluminum by a Monte Carlo uncertainty analysis algorithm programmed in FORTRAN. The results show that the optimum thickness of the aluminum absorber is 100
μm, for which the contribution of Ti K X-rays in air kerma strength is reduced to less than one hundredth of the uncertainty in the correction factor, ensuring that the uncertainty in the air kerma strength will be mainly due to the uncertainty in the correction factor. The calculated uncertainties are 1.7
×
10
−3, and 3.4
×
10
−3 for
125I and
103Pd sources, respectively. |
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ISSN: | 0306-4549 1873-2100 |
DOI: | 10.1016/j.anucene.2010.09.006 |