Published in:
01-11-2008 | Original Article
Hepatic absorbed radiation dosimetry during I-131 Metaiodobenzylguanadine (MIBG) therapy for refractory neuroblastoma
Authors:
Kenneth F. Koral, John P. Huberty, Bill Frame, Katherine K. Matthay, John M. Maris, Denise Regan, Daniel Normolle, Gregory A. Yanik
Published in:
European Journal of Nuclear Medicine and Molecular Imaging
|
Issue 11/2008
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Abstract
Purpose
To compare the prediction of therapeutic hepatic radiation-absorbed dose rates from tracer imaging plus a linearity assumption to estimation based on intra-therapy imaging in 131I metaiodobenzylguanidine (MIBG) therapy of refractory neuroblastoma.
Materials and methods
Conjugate-view images of the liver were obtained before therapy for seven patients at seven times after a tracer infusion of 131I MIBG and at three times after the therapy infusion. Measured liver activities were converted to dose-rate estimates. Three statistical models of the rates assuming double exponential dependences on time were examined. One of the three models allowed for a multiplicative correction to the therapeutic late-phase dose-rate amplitude. Results from that model: (1) the tracer prediction of the late-phase absorbed-dose-rate amplitude was a factor of 1.75 times the intra-therapy-estimated value, and (2) the difference between tracer prediction of the radiation-absorbed dose and intra-therapy estimation of it was statistically significant, and (3) the liver radiation-absorbed dose did not reach 30 Gy.
Conclusions
A statistical modeling analysis finds that the radiation-absorbed dose after therapy appears to be lower than that which is predicted from the linear scaling with administered activity of the tracer radiation-absorbed dose. Hepatocyte toxicity is the most likely reason but it is not high enough to produce clinically observable results.