title: Single-cell dosimetry for radioimmunotherapy of B-cell lymphoma patients with special reference to leukemic spread.
abstract: OBJECTIVE
  Many lymphoma patients have both macroscopic tumors and single-cell manifestations of their disease. Treatment efficacy could, therefore, depend on the radionuclide used. The aim of this study was to investigate dosimetry at a cellular level for three isotopes of radioiodine.
  
  
  METHODS
  Cells were assumed to be spherical with radii of 6.35, 7.7, and 9.05 microm corresponding to the dimensions of the Raji cells. The radius of the nucleus was assumed to be 75% of the cellular radius. The electron energies were 18, 28, and 190 keV, corresponding to the mean electron energy per decay for (125)I, (123)I, and (131)I, respectively. S-values for different activity distributions were simulated using Monte Carlo and dose-volume histograms as well as absorbed doses, and absorbed dose rates were calculated.
  
  
  RESULTS
  (125)I gives the highest absorbed dose (approximately 4-40 times that of (131)I), whereas (123)I will give the highest absorbed dose rate (approximately 100 times that of (131)I). Under the given assumptions, the absorbed dose at this level is more dependent on the size of the cells than on whether the radioimmunoconjugate is internalized.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Foundation Trust, Sutton, Surrey, United Kingdom. cecilia.hindorf@icr.ac.uk
authors.forename: Cecilia
authors.initials: C
authors.lastname: Hindorf
authors.forename: Dimitris
authors.initials: D
authors.lastname: Emfietzoglou
authors.forename: Ola
authors.initials: O
authors.lastname: Lindén
authors.forename: Christos
authors.initials: C
authors.lastname: Bousis
authors.forename: Andreas
authors.initials: A
authors.lastname: Fotopoulos
authors.forename: Kostas
authors.initials: K
authors.lastname: Kostarelos
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Flux
mesh_terms: D000042:Absorption; D004583:Electrons; D006207:Half-Life; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D016393:Lymphoma, B-Cell / Q000473:pathology* / Q000532:radiotherapy*; D017785:Photons; D016499:Radioimmunotherapy / Q000379:methods*; D011879:Radiotherapy Dosage
chemical_list: D007457:Iodine Radioisotopes