title: Dosimetric results in treatments of neuroblastoma and neuroendocrine tumors with (131)I-metaiodobenzylguanidine with implications for the activity to administer.
abstract: OBJECTIVE
  The aim was to investigate whole-body and red marrow absorbed doses in treatments of neuroblastoma (NB) and adult neuroendocrine tumors (NETs) with (131)I-metaiodobenzylguanidine and to propose a simple method for determining the activity to administer when dosimetric data for the individual patient are not available.
  
  
  METHODS
  Nine NB patients and six NET patients were included, giving in total 19 treatments as four patients were treated twice. Whole-body absorbed doses were determined from dose-rate measurements and planar gamma-camera imaging. For six NB and five NET treatments, red marrow absorbed doses were also determined using the blood-based method.
  
  
  RESULTS
  Dosimetric data from repeated administrations in the same patient were consistent. In groups of NB and NET patients, similar whole-body residence times were obtained, implying that whole-body absorbed dose per unit of administered activity could be reasonably well described as a power function of the patient mass. For NB, this functional form was found to be consistent with dosimetric data from previously published studies. The whole-body to red marrow absorbed dose ratio was similar among patients, with values of 1.4 ± 0.6-1.7 ± 0.7 (1 standard deviation) in NB treatments and between 1.5 ± 0.6 and 1.7 ± 0.7 (1 standard deviation) in NET treatments.
  
  
  CONCLUSIONS
  The consistency of dosimetric results between administrations for the same patient supports prescription of the activity based on dosimetry performed in pretreatment studies, or during the first administration in a fractionated schedule. The expressions obtained for whole-body absorbed doses per unit of administered activity as a function of patient mass for NB and NET treatments are believed to be a useful tool to estimate the activity to administer at the stage when the individual patient biokinetics has not yet been measured.
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund 22185, Sweden and Department of Medical Physics, Gurutzeta/Cruces University Hospital, Barakaldo 48903, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Mínguez
authors.affiliation: Joint Department of Physics, Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton SM2 5PT, United Kingdom.
authors.forename: Glenn
authors.initials: G
authors.lastname: Flux
authors.affiliation: Department of Nuclear Medicine, Gurutzeta/Cruces University Hospital, Barakaldo 48903, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Genollá
authors.affiliation: Department of Nuclear Medicine, Gurutzeta/Cruces University Hospital, Barakaldo 48903, Spain.
authors.forename: Sonía
authors.initials: S
authors.lastname: Guayambuco
authors.affiliation: Department of Nuclear Medicine, Gurutzeta/Cruces University Hospital, Barakaldo 48903, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Delgado
authors.affiliation: Department of Nuclear Medicine, Gurutzeta/Cruces University Hospital, Barakaldo 48903, Spain.
authors.forename: José Cruz
authors.initials: JC
authors.lastname: Fombellida
authors.affiliation: Department of Medical Radiation Physics, Lund University, Lund 22185, Sweden.
authors.forename: Katarina
authors.initials: K
authors.lastname: Sjögreen Gleisner
mesh_terms: D019797:3-Iodobenzylguanidine / Q000009:adverse effects / Q000627:therapeutic use*; D000293:Adolescent; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000528:radiation effects; D002648:Child; D002675:Child, Preschool; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D009447:Neuroblastoma / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011877:Radionuclide Imaging; D011879:Radiotherapy Dosage; D014915:Whole-Body Counting; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D019797:3-Iodobenzylguanidine