Single-Cell Dosimetry for Radioimmunotherapy of B-Cell Lymphoma Patients with Special Reference to Leukemic Spread

Abstract

This enquiry showed that both (123)I and (125)I have greater potential than (131)I for the treatment of leukemic spread in patients with lymphoma.

CELLDOSE: A Monte Carlo Code to Assess Electron Dose Distribution—S Values for 131I in Spheres of Various Sizes

“…The absorbed fraction of electrons from 131 I reaches 95% for a sphere of 1 g with a 6.2 mm radius (25). However, this fraction will decrease with decreasing sphere size, as shown in Table 1 and Figure 3, indicating that 131 I may be less efficient for treatment of small tumor targets (micrometastases, tumor cell clusters, and isolated tumor cells), as has also been reported by Hindorf et al for lymphoma cells (26). Indeed, a substantial proportion of the disintegration energy escapes and is deposited outside the tumor volume.…”

Monte Carlo single-cell dosimetry of I-131, I-125 and I-123 for targeted radioimmunotherapy of B-cell lymphoma

“…However, in vitro experiments (Hansen et al 1996, Stein et al 2003 indicate that a sizeable fraction (∼ 20-40%) of the initial surface-bound radioactivity can be eliminated from the cell within the first 2-3 days for a residualizing internalized MAb. Thus, in the present work, we further extend the previous studies by Hindorf et al (2007) and Bousis (et al 2010) by employing a typical -biologic halftime, T b , of 48 hours (Stein et al 2003) for the internalized radionuclides. Moreover, we perform calculations for 131 I using its full emission spectrum and compare with the results of Hindorf et al (2007).…”

“…Both use cluster of differentiation (CD) 20-targeting MAb that are not internalized in the cell, labeled with the b-emitters 90 Y (Zevalin) and 131 I (Bexxar). A recent dosimetry study by Hindorf et al (2007) showed that the Auger emitters 125 I and 123 I have greater potential than 131 I for treatment of B-cell lymphoma patients. However, these dosimetric calculations were carried out using the mean energies per decay of the three radioiodines and a simple condensed-history scheme based on the continuous-slowing-down-approximation.…”

“…However, these dosimetric calculations were carried out using the mean energies per decay of the three radioiodines and a simple condensed-history scheme based on the continuous-slowing-down-approximation. In a latter work, we revisited and improved upon the dosimetric calculations of Hindorf et al (2007) for 125 I and 123 I by using: (i) The full Auger spectrum of these radionuclides and, (ii) a more accurate MC transport scheme with full account of straggling which goes beyond the continuous-slowing-down-approximation (Bousis et al 2010). Unfortunately, these studies , Bousis et al (2010) were performed under the oversimplified assumption of permanent retention of the radionuclides once they were internalized.…”

The COOLER Code: A Novel Analytical Approach to Calculate Subcellular Energy Deposition by Internal Electron Emitters

“…Because detailed simulation of electron tracks can be time consuming, condensed history transport codes have often been employed to approach various cellular dosimetric problems (26)(27)(28)(29)(30)(31)(32). Among the shortcomings of using condensed history codes, we point out the adoption of large energy cutoff for electron transport, typically between 1 and 10 keV, which results in a spatial resolution of the order of the biological target.…”