Evaluating the Application of Tissue-Specific Dose Kernels Instead of Water Dose Kernels in Internal Dosimetry: A Monte Carlo Study

Maryam Khazaee Moghadam, Alireza Kamali Asl*, Parham Geramifar, Habib Zaidi

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    12 Citations (Scopus)

    Abstract

    Purpose: The aim of this work is to evaluate the application of tissue-specific dose kernels instead of water dose kernels to improve the accuracy of patient-specific dosimetry by taking tissue heterogeneities into consideration.

    Materials and Methods: Tissue-specific dose point kernels (DPKs) and dose voxel kernels (DVKs) for yttrium-90 (Y-90), lutetium-177 (Lu-177), and phosphorus-32 (P-32) are calculated using the Monte Carlo (MC) simulation code GATE (version 7). The calculated DPKs for bone, lung, adipose, breast, heart, intestine, kidney, liver, and spleen are compared with those of water. The dose distribution in normal and tumorous tissues in lung, liver, and bone of a Zubal phantom is calculated using tissue-specific DVKs instead of those of water in conventional methods. For a tumor defined in a heterogeneous region in the Zubal phantom, the absorbed dose is calculated using a proposed algorithm, taking tissue heterogeneity into account. The algorithm is validated against full MC simulations.

    Results: The simulation results indicate that the highest differences between water and other tissue DPKs occur in bone for Y-90 (12.2%+/- 0.6%), P-32 (18.8%+/- 1.3%), and Lu-177 (16.9%+/- 1.3%). The second highest discrepancy corresponds to the lung for Y-90 (6.3%+/- 0.2%), P-32 (8.9%+/- 0.4%), and Lu-177 (7.7%+/- 0.3%). For Y-90, the mean absorbed dose in tumorous and normal tissues is calculated using tissue-specific DVKs in lung, liver, and bone. The results are compared with doses calculated considering the Zubal phantom water equivalent and the relative differences are 4.50%, 0.73%, and 12.23%, respectively. For the tumor in the heterogeneous region of the Zubal phantom that includes lung, liver, and bone, the relative difference between mean calculated dose in tumorous and normal tissues based on the proposed algorithm and the values obtained from full MC dosimetry is 5.18%.

    Conclusions: A novel technique is proposed considering tissue-specific dose kernels in the dose calculation algorithm. This algorithm potentially enables patient-specific dosimetry and improves estimation of the average absorbed dose of Y-90 in a tumor located in lung, bone, and soft tissue interface by 6.98% compared with the conventional methods.

    Original languageEnglish
    Pages (from-to)367-379
    Number of pages13
    JournalCANCER BIOTHERAPY AND RADIOPHARMACEUTICALS
    Volume31
    Issue number10
    DOIs
    Publication statusPublished - Dec-2016

    Keywords

    • dose point kernel
    • Monte Carlo simulation
    • patient-specific dosimetry
    • tissue heterogeneity
    • POINT KERNELS
    • SIMULATION TOOLKIT
    • RADIONUCLIDE THERAPY
    • Y-90
    • ELECTRON
    • GATE
    • MICROSPHERES
    • CONVOLUTION
    • VALIDATION
    • INTERFACE

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