Therapeutic potential of90Y- and131I-labeled anti-CD20 monoclonal antibody in treating non-Hodgkin's lymphoma with pulmonary involvement: A Monte Carlo-based dosimetric analysis

Hong Song, Yong Du, George Sgouros, Andrew Prideaux, Eric Frey, Richard L. Wahl

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Pulmonary involvement is common in patients with non-Hodgkin's lymphoma (NHL). 90Y- and 131I-anti-CD20 antibodies (ibritumomab tiuxetan and tositumomab, respectively) have been approved for the treatment of refractory low-grade follicular NHL. In this work, we used Monte Carlo-based dosimetry to compare the potential of 90Y and 131I, based purely on their emission properties, in targeted therapy for NHL lung metastases of various nodule sizes and tumor burdens. Methods: Lung metastases were simulated as spheres, with radii ranging from 0.2 to 5.0 cm, which were randomly distributed in a voxelized adult male lung phantom. Total tumor burden was varied from 0.2 to 1,641 g. Tumor uptake and retention kinetics of the 2 radionuclides were assumed equivalent; a uniform distribution of activity within tumors was assumed. Absorbed dose to tumors and lung parenchyma per unit activity in lung tumors was calculated by a Monte Carlo-based system using the MCNP4B package. Therapeutic efficacy was defined as the ratio of mean absorbed dose in the tumor to that in normal lung. Dosimetric analysis was also performed for a lung-surface distribution of tumor nodules mimicking pleural metastatic disease. Results: The therapeutic efficacy of both 90Y and 131I declined with increasing tumor burden. In treating tumors with radii less than 2.0 cm, 131I targeting was more efficacious than 90Y targeting. 90Y yielded a broader distribution of tumor absorbed doses, with the minimum 54.1% lower than the average dose; for 131I, the minimum absorbed dose was 33.3% lower than the average. The absorbed dose to normal lungs was reduced when the tumors were distributed on the lung surface. For surface tumors, the reductions in normal-lung absorbed dose were greater for 90Y than for 131I, but 131I continued to provide a greater therapeutic ratio across different tumor burdens and sizes. Conclusion: Monte Carlo-based dosimetry was performed to compare the therapeutic potential of 90Y and 131I targeting of lung metastases in NHL patients. 131I provided a therapeutic advantage over 90Y, especially in tumors with radii less than 2.0 cm and at lower tumor burdens. For both 90Y- and 131I-labeled antibodies, treatment ismore efficacious when applied to metastatic NHL cases with lower tumor burdens. 131I has advantages over 90Y in treating smaller lung metastases.

Original languageEnglish (US)
Pages (from-to)150-157
Number of pages8
JournalJournal of Nuclear Medicine
Issue number1
StatePublished - Jan 1 2007


  • Dosimetry
  • I
  • Monte Carlo
  • Non-Hodgkin's lymphoma
  • Pulmonary metastases
  • Y

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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