Radiation emission dose from patients administered 90Y-labelled radiopharmaceuticals: comparison of experimental measurements versus Monte Carlo simulation.
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.
Meo
Sergio Lo
SL
Laboratory of Ionizing Radiation-ISPESL, Monte Porzio Catone, Roma, Italy.
Cicoria
Gianfranco
G
Montini
Giancarlo
G
Bergamini
Carlo
C
Campanella
Francesco
F
Pancaldi
Davide
D
Panebianco
Antonio Sabatino
AS
Rubello
Domenico
D
Marengo
Mario
M
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
D000911:Antibodies, Monoclonal; D019275:Radiopharmaceuticals; C422802:ibritumomab tiuxetan