Hepatic Structural Dosimetry in 90Y Microsphere Treatment: A Monte Carlo Modeling Approach Based on Lobular Microanatomy

Journal of Nuclear Medicine

Manuel L. Sztejnberg¹  Jeffry A. Siegel¹  Seza A. Gulec¹  Michael Stabin¹  Tatjana Jevremovic¹ 

关键词: hepatology;    oncology;    radiobiology/dosimetry;    radionuclide therapy;    hepatic structural dosimetry;    MCNPX;    SIRT;    ⁹⁰Y microspheres;   

DOI  :  10.2967/jnumed.109.069278

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Selective internal radiation treatment (SIRT) via intrahepatic arterial administration of 90Y microspheres is an effective therapeutic modality. The conventional and generally applied MIRD schema is based on the premise that the distribution of microspheres in the liver parenchyma is uniform. In reality, however, the distribution of the microspheres follows a distinct pattern, requiring that a model be developed to more appropriately estimate radiation absorbed doses to the different structural/functional elements of the hepatic microanatomy. Methods: A systematic investigation was performed encompassing a conventional average absorbed dose assessment, a compartmental macrodosimetric approach that accounts for the anticipated higher tumor–to–normal liver activity concentration ratio, dose point-kernel convolution–derived estimates, and Monte Carlo dose estimates employing a spherical and 3-dimensional hexagonal liver model, including various subunits of the hepatic anatomy, down to the micrometer level. Results: Detailed specifics of the radiation dose deposition of 90Y microspheres demonstrated a rapid decrease in absorbed dose in and around the portal tracts where the microspheres are deposited. The model also demonstrated that the hepatocellular parenchymal and central vein doses could be at significant levels because of a cross-fire effect. Conclusion: The reported microstructural dosimetry models can help in the detailed assessment of the dose distributions in the hepatic functional subunits and in relating these doses to their effects. These models have also revealed that the there is a consistent relationship between the average liver dose as calculated by MIRD macrodosimetry and the structural dosimetry estimates in support of the clinical utility of the MIRD methodology. This relationship could be used to more realistically assess patterns of hepatic toxicity associated with the 90Y SIRT treatment.

【 授权许可】

Unknown