PT  - JOURNAL ARTICLE
AU  - Jonathan van Vliet
AU  - Stephan van Hoesel
AU  - Rob Kreuger
AU  - Frederik Beekman
TI  - Nano TRACTor: 1000 frames per minute slit SPECT for radiolabeled particle tracking
DP  - 2015 May 01
TA  - Journal of Nuclear Medicine
PG  - 1872--1872
VI  - 56
IP  - supplement 3
4099  - http://jnm.snmjournals.org/content/56/supplement_3/1872.short
4100  - http://jnm.snmjournals.org/content/56/supplement_3/1872.full
SO  - J Nucl Med2015 May 01; 56
AB  - 1872 Objectives Fast and precise in vivo tracking of nanoparticles or single cells could provide better understanding of drug and stem cell delivery. Present SPECT with traditional collimators lack sensitivity to achieve sufficiently high frame rates. In this project a multi-slit SPECT system with stationary detectors was designed to track nanoparticles with frame rates of 1000 frames per minute and a precision down to ~1 mm in a mouse-sized field of view (Ø25mmx100mm).Methods The SPECT system used has three large gamma cameras in a stationary triangular configuration. A 198Au nanoparticle of 6 µm diameter can be activated as high as ~37 kBq and is inert in an aqueous solution, which makes it very suitable for in-vivo particle tracking. To track such a particle, a collimator system with four slits in the axial direction and one slit in the transversal plane was designed with a geometric sensitivity higher than 0.5% per slit. Through each slit the particle gives a line-shaped response on a gamma camera. The position of the particle is found by solving the least squares solution of the intersection of the five planes defined by slits and the corresponding detector line responses. Simulations were made to optimise the design and evaluate the precision of this system. A preliminary system with a much larger field of view was used to track a rotating 99mTc source for initial validation.Results First measurements showed that the moving source could be tracked with a precision better than 1 mm at 600 frames per minute. Simulations demonstrate that one can track a 37 kBq 198Au nanoparticle with the optimised slit system up to 1000 frames per minute with a precision better than 1.4 mm (FWHM) in the axial direction and 0.4 mm (FWHM) in the transversal plane.Conclusions Our results indicate that Nano TRACTor is capable of tracking single radiolabeled particles at extremely high frame rates and a resolution close to a millimeter in small animals. This may open many new possibilities for e.g. nanoparticle and stem cell imaging.