title: Radiation emission dose from patients administered 90Y-labelled radiopharmaceuticals: comparison of experimental measurements versus Monte Carlo simulation.
abstract: OBJECTIVE
  To estimate the radiation dose delivered from patients injected with yttrium-90 (Y)-labelled tiuxetan (Zevalin) to parents and the general population, comparing different techniques.
  
  
  METHODS
  The radiation dose delivered from a group of eight patients injected with Y-Zevalin to treat recurrent lymphoma was measured. The data obtained with the Monte Carlo simulation test were compared with the experimental measurements obtained with an ionization chamber detector and with a crystal NaI(Tl) detector.
  
  
  RESULTS
  A good correlation was found between the Monte Carlo simulation test and the ionization chamber detector results: the air kerma dose rate was 4.2+/-0.1 and 4.4+/-0.8 microGy/h, respectively (r=0.9, P<0.01). Moreover, more than 99.7% of the air kerma dose rate measured with the ionization chamber detector was because of the contribution of electrons, whereas the contribution of photons was less than 0.3%. In contrast, the air kerma dose rate measured with the crystal NaI(Tl) detector was significantly lower (0.76+0.12 microGy/h) in comparison with the Monte Carlo simulation test. This underestimation was related to the limited crystal NaI(Tl) detector response to low energy rates at variance with the ionization chamber detector. The effective radiation dose released by patients treated with Y-labelled tiuxetan to parents and the general population was approximately 0.1 mSv per treatment cycle.
  
  
  CONCLUSIONS
  Using the Monte Carlo model as a benchmark to compare the experimental measurements obtained by the two different detectors, we found that the ionizing chamber detector was more accurate than the crystal Na(Tl) detector for measuring the exposure radiation dose delivered from patients administered with Y-labelled radiopharmaceuticals. Moreover, the effective radiation dose released by these patients to their parents and the general population is significantly lower than the value recommended by international reports and regulations.
authors.affiliation: Laboratory of Ionizing Radiation-ISPESL, Monte Porzio Catone, Roma, Italy.
authors.forename: Sergio Lo
authors.initials: SL
authors.lastname: Meo
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Cicoria
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Montini
authors.forename: Carlo
authors.initials: C
authors.lastname: Bergamini
authors.forename: Francesco
authors.initials: F
authors.lastname: Campanella
authors.forename: Davide
authors.initials: D
authors.lastname: Pancaldi
authors.forename: Antonio Sabatino
authors.initials: AS
authors.lastname: Panebianco
authors.forename: Domenico
authors.initials: D
authors.lastname: Rubello
authors.forename: Mario
authors.initials: M
authors.lastname: Marengo
mesh_terms: D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000627:therapeutic use*; D004579:Electron Transport; D004781:Environmental Exposure; D006282:Health Personnel; D006801:Humans; D008954:Models, Biological; D009010:Monte Carlo Method; D010290:Parents; D017785:Photons; D011829:Radiation Dosage; D019275:Radiopharmaceuticals / Q000008:administration & dosage / Q000627:therapeutic use*; D013194:Staining and Labeling
chemical_list: D000911:Antibodies, Monoclonal; D019275:Radiopharmaceuticals; C422802:ibritumomab tiuxetan