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Inventi Rapid - Biomedical Engineering

Articles

  • Inventi:ebe/5/11
    MEASUREMENT AND CALCULATION OF HETEROGENEITY CORRECTION FACTOR FOR AN IR-192 MHDR SOURCE IN THE PRESENCE OF INHOMOGENEITIES
    C S Sureka, K V Subbaiah, P Aruna

    The purpose of our study was to analyze the effect of inhomogeneities on dose estimation near an Ir-192 source. Heterogeneity correction factors (HCFs) are calculated using Monte Carlo method and the computed values are compared with the experimentally measured values using ion chamber for different inhomogeneities viz. air, PMMA, polystyrene, water, bone, soft tissue and polysulphone in various phantom conditions viz. in-air, RTPS-PMMA and in-water phantoms. Study reveals that the dose correction factors are of the order of 15 % to 34 %. The agreement between measured and calculated HCFs was found to be within 7 %. The reason for this discrepancy is not clear although it could be related to the geometry of the ion chamber which is 4 cm in diameter and 1.2 cm thick. Hence, it is concluded that the accuracy of dose calculation in brachytherapy and the problem of inhomogeneity correction will become increasingly more important in the future. Further, the Monte Carlo simulation may be used to calculate basic dosimetry data in order to minimizing the dosimetric perturbation arises due to tissue inhomogeneities.

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