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Dosimetry Study of 99mTc-NTP 15-5 Imaging of Cartilage in Preclinical Trials Using the GATE Monte Carlo Platform

G Fois

G Fois1*, F Cachin2 , E Jouberton2,3 , E Miot-Noirault3 , N Sas2 , C Valla2 , L Maigne1 , (1) Laboratoire de Physique de Clermont UMR 6533 CNRS-IN2P3-Clermont Auvergne University, Aubiere, France (2) CLCC Jean Perrin, Clermont-ferrand, France (3)UMR 1240 INSERM-Clermont Auvergne University, Clermont Ferrand, France


SU-E-708-6 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 708

Purpose: Osteoarthritis is one of the most common musculoskeletal disorders, it is a slowly progressive pathology characterized by cartilage destruction leading to joint instability and painful symptoms.A sensitive imaging approach is essential to quantify osteoarthritis progression and monitor response to new therapies.In this context, INSERM/UCA-UMR1240 developed a radiotracer called 99mTc-NTP 15-5 (world patent WO 01/00621 A1), which binds to cartilage proteoglycans whose decrease content is associated to a loss of biomedical function of cartilage. We have implemented the whole dosimetry study concerning this new radiotracer for rabbits using the GATE Monte Carlo platform.

Methods: Absorbed doses to critical organs is determined using the MIRD formalism. Bio-distribution data are obtained by organ harvesting, measuring the activity in organs at different times. Sources are cartilage in knees and intervertebral disks due to fixation of 99mTc-NTP 15-5 (cumulated activity in cartilage is about 80MBq/g), with liver and kidneys. S-factors are calculated for 4 rabbit’s CT scan. A particular attention is given to dose calculation in bones, bone marrow and organs at risk.Dose is estimated in a human model calculating S-factors from a patient CT scan with GATE. Bio-distribution is extrapolated to humans using the %kg-dose/g method.

Results: The dosimetry performed in animal model, show self doses for organs such as liver and kidneys in the order of tens of μGy per MBq of injected activity.

Conclusion: The dosimetry profile of 99mTc-NTP 15-5, in the context of preclinical trials, is of major importance in order to make sure that organs at risk are not overexposed. GATE gathers now all the facilities to calculate dose profiles for internal dosimetry. The extrapolation of the dose for a human model is a first step towards clinical trials.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by grants from ANR (Agence Nationale pour la Recherche), Programme Recherche translationnelle en sante (DS0411) 2015 under contract ANR-15-CE18-003 and from ITMO Technologies pour la sante - AVIESAN

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