Human Biodistribution and Dosimetry of the PET Radioligand [11C]Flumazenil (FMZ)

Abstract

On average, the administration of less than 790 MBq (21 mCi) of [¹¹C]FMZ yields (no voiding model) an organ equivalent dose of under 50 mSv [the single dose limit for research studies under US regulations (21CFR361.1) to body organs other than blood forming organs, gonads or the lens of the eye] to all organs. Equivalent dose to the blood forming organs and gonads from a 790 MBq administered FMZ dose is well under the 30 mSv limit provided under 21CFR361.1. Additionally, administration of less than 1320 MBq (35.7 mCi) yields an effective dose [International Commission on Radiation Protection (ICRP) 60 tissue weighting scheme] of under 10 mSv, which is the ICRP IIb (minor to intermediate) risk category limit.

11C Dosimetry Scans Should Be Abandoned

“…For instance, the choice of using a dynamic bladder model and its voiding time may significantly affect the final dose. The doses for different voiding times are not systematically reported, but, for example, a faster voiding schedule would reduce the effective dose of 11 C-flumazenil by 13% (5) and that of 18 F-CP-18 by 61% (6).…”