Initial tests of a new phantom for investigation of spatial resolution, partial volume effect and detectability in nuclear medicine tomography

A new phantom has been designed that can provide simultaneously different target to background activity ratios with a linearly changing diameter of lesions. The purpose of the study was to describe and perform initial measurements with the phantom aimed to characterize different nuclear medicine tomographic systems and reconstruction algorithms in their performance and behaviour concerning partial volume effect (PVE) and detectability by varying the acquisition parameters and the count statistics. The phantom has an external vessel whose outline is half-cylindrical and allows it to be incorporated into an anthropomorphic thorax phantom. The phantom itself contains 16 fillable cones with an inner diameter linearly decreasing from 16 mm to 2 mm and a wall thickness of 1 mm acrylic glass. They as well as the outer vessel were separately filled with 99mTc- and 18F-solutions respectively of different activity concentrations. The phantom was easy to fill and air bubbles could easily be avoided. Images taken using a SPECT/CT and a PET/CT system are presented as well as evaluations of PVE. The new phantom seems to be useful for comparison and optimisation of different acquisition and reconstruction parameters in nuclear medicine tomographic studies and for comparisons between various tomographic units.