title: Prediction of radiation doses from therapy using tracer studies with iodine-131-labeled antibodies.
abstract: Tracer pharmacokinetic studies are often used in treatment planning for radionuclide therapy including radioimmunotherapy. This study evaluates the validity of using tracer studies to predict radiation doses from therapy with the same radiolabeled antibody.
  
  
  METHODS
  Quantitative imaging and blood radioactivity were used to obtain the pharmacokinetics and radiation doses that were delivered to the total body, blood, marrow, lungs, liver, kidneys, thyroid, spleen and tumors. Tracer and therapy data for eight patients with lymphoma and one patient with breast cancer were compared using linear regression statistics. Doses of 131I-labeled antibody for the tracer studies ranged from 0.1 to 0.4 GBq (2 to 10 mCi), and therapy doses ranged from 0.7 to 5.6 GBq (20 to 150 mCi).
  
  
  RESULTS
  Radiation doses to tissues and, in particular, the bone marrow and tumors were reliably predicted from tracer studies. In this group of patients, median dose to marrow from marrow targeting, total body and blood was 9.2 cGy/GBq for tracer studies and 7.6 cGy/GBq for therapy studies with a median difference of 0.5 cGy/GBq. Median dose to tumors was 81.1 cGy/GBq for tracer studies and 70.3 cGy/GBq for therapy studies with a median difference of 5.9 cGy/GBq.
  
  
  CONCLUSIONS
  In these patients, tracer studies were predictive of the radiation doses from therapy for total body, major organs and tumors. The radiation doses to marrow and tumors, which are the usual determinants of the therapeutic index, correlated well between tracer and therapy studies (r > or = 0.95).
authors.affiliation: Department of Internal Medicine, University of California Davis Medical Center, Sacramento, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: DeNardo
authors.forename: G L
authors.initials: GL
authors.lastname: DeNardo
authors.forename: A
authors.initials: A
authors.lastname: Yuan
authors.forename: S
authors.initials: S
authors.lastname: Shen
authors.forename: S J
authors.initials: SJ
authors.lastname: DeNardo
authors.forename: D J
authors.initials: DJ
authors.lastname: Macey
authors.forename: K R
authors.initials: KR
authors.lastname: Lamborn
authors.forename: M
authors.initials: M
authors.lastname: Mahe
authors.forename: M W
authors.initials: MW
authors.lastname: Groch
authors.forename: W D
authors.initials: WD
authors.lastname: Erwin
mesh_terms: D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000627:therapeutic use; D001853:Bone Marrow / Q000528:radiation effects; D001943:Breast Neoplasms / Q000532:radiotherapy; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000627:therapeutic use*; D008228:Lymphoma, Non-Hodgkin / Q000532:radiotherapy; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000532:radiotherapy; D016499:Radioimmunotherapy; D011879:Radiotherapy Dosage
chemical_list: D000911:Antibodies, Monoclonal; D007457:Iodine Radioisotopes