Radiation dosimetry of N-([11C]methyl)benperidol as determined by whole-body PET imaging of primates

Abstract

Purpose-N-([ 11 C]methyl)benperidol ([ 11 C]NMB) can be used for positron emission tomography (PET) measurements of D 2 -like dopamine receptor binding in vivo. We report the absorbed radiation dosimetry of i.v.-administered 11 C-NMB, a critical step before applying this radioligand to imaging studies in humans.Materials and methods-Whole-body PET imaging with a CTI/Siemens ECAT 953B scanner was done in a male and a female baboon. After i.v. injection of 444-1221 MBq of 11 C-NMB, sequential images taken from the head to the pelvis were collected for 3 h. Volumes of interest (VOIs) were identified that entirely encompassed small organs (whole brain, striatum, eyes, and myocardium). Large organs (liver, lungs, kidneys, lower large intestine, and urinary bladder) were sampled by drawing representative regions within the organ volume. Time-activity curves for each VOI were extracted from the PET, and organ residence times were calculated by analytical integration of a multi-exponential fit of the time-activity curves. Human radiation doses were estimated using OLINDA/EXM 1.0 and the standard human model.Results-Highest retention was observed in the blood and liver, each with total residence times of 1.5 min. The highest absorbed radiation doses were to the heart (10.5 mGy/kBq) and kidney (9.19 mGy/kBq), making these the critical organs for [ 11 C]NMB. A heart absorption of 50 mGy would result from an injected dose of 4,762 MBq [ 11 C]NMB.

Whole-Body Distribution and Radiation Dosimetry of68Ga-NOTA-RGD, a Positron Emission Tomography Agent for Angiogenesis Imaging

“…20,21 The mean activity per unit volume of sub-sampled VOI was not applied in this study, because average subject weight was significantly lower than the standard adult male and female model (73.7 and 56.9 kg) in OLINDA/EXM software (version 1.1, Vanderbilt University, 2007), which was used for dose calculation. 21,22 Furthermore, subject organ volumes were not identical with those of standard phantom models.…”

Radiation dosimetry and biodistribution in non-human primates of the sodium/iodide PET ligand [18F]-tetrafluoroborate

“…For the spleen, the residence time was calculated from the blood fraction of the spleen, which is 1.5 % of its volume [ 17 ]. For the red marrow, its residence time is taken from [ 18 , 19 ]: …”

Development of a nonhuman primate computational phantom for radiation dosimetry

“…Prior to the development of the NHP phantom described in this work, human models were used as an approximation for the assessment of radiation doses to NHP models from studies involving the use of radiopharmaceuticals to obtain the pharmacokinetics and estimate the absorbed dose in the human body. [9][10][11][12] Total body weight is the most commonly used matching criteria for substitute phantom selection while the torso length or standing height can be used as secondary criteria. 21 The weight of the ICRP reference newborn phantom is 3.5 kg (81% of the mass of the NHP phantom) while the body length of the 1-yr-old human phantom is 76.8 cm (1 cm longer than the NHP phantom).…”

“…7,8 As such, human models were commonly used to perform dosimetry calculations. [9][10][11][12] Therefore, there is a need for such models and detailed dose estimates to fill a gap in the radiation dosimetry literature.…”