Abstract
BackgroundRadiomercury 197mHg and 197Hg, henceforth referred to as 197(m)Hg, is a promising theranostic radionuclide endowed with properties that allow diagnostic and therapeutic applications. The aim of this work was to investigate the capabilities of 197(m)Hg for nuclear medicine imaging. Therefore measurements were performed by using a Philips BrightView SPECT camera. Furthermore, Monte Carlo simulations using the GATE software were performed to theoretically explore the imaging contribution from the various gamma and X-ray emissions from 197(m)Hg for a commercial clinical camera with low-energy high-resolution (LEHR) and high-energy general-purpose (HEGP) collimators. We estimated the spatial resolution by using a four-quadrant bar phantom, and we evaluated the planar and tomographic images from an abdominal phantom containing three cylindrical sources of 197(m)Hg solution.ResultsA good accordance between measurements and simulations was found for planar and SPECT imaging. Simulations allowed the decomposition of the detected energy spectrum into photon origins. Measurements and simulations for the bar phantom revealed that for the LEHR collimator, the 6-mm pattern could be resolved, whereas for the HEGP collimator, the resolution is about 10 mm. Furthermore, we found that no significant image distortion results from high-energy photons when using the LEHR collimator.ConclusionsWe demonstrated the imaging capabilities of 197(m)Hg which is essential both for diagnostic applications and to determine the in vivo biodistribution for dose calculations in therapeutic applications.
Highlights
Radiomercury 197mHg and 197Hg, referred to as 197(m)Hg, is a promising theranostic radionuclide endowed with properties that allow diagnostic and therapeutic applications
A good accordance between measurements and simulations was found for planar and SPECT imaging
Simulations allowed the decomposition of the detected energy spectrum into photon origins
Summary
Radiomercury 197mHg and 197Hg, referred to as 197(m)Hg, is a promising theranostic radionuclide endowed with properties that allow diagnostic and therapeutic applications. The physical fundament of nuclear medicine is the application of radioactive isotopes. It is favorable that the isotopes emit gamma radiation with energies of a few hundred kiloelectron volt like 99mTc, 123I, or 111In. For therapeutic application, alpha- or beta-particle emitting radionuclides are applied to achieve a large dose deposition in tumors or metastases like 223Ra, 90Y, 177Lu, and 188Re. Freudenberg et al EJNMMI Physics (2018) 5:15. It is mandatory to estimate the absorbed dose. To this end, pre-therapeutic imaging is performed in order to visualize the distribution of lesions and to estimate the biokinetics of the radionuclides. A special focus is on the development of “theranostic” radioisotopes that combine the advantages of therapeutic and diagnostic radioisotopes
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