Large Chest Phantom for Positron Emission Tomography

The aim of this work is to make the large chest anthropomorphic phantom that closely mimicks the average american adult (male) chest.

Interior of the Phantom: There are a total of 16 spheres (tumors) inside the phantom. This includes 12 Clinical Trial Network (CTN) chest phantom spheres (37, 28, 22, 22, 17, 17, 13, 13, 10, 10, 10, 7 mm) and four additional spheres of internal diameters (19, 15.5, 11.5, and 8.5 mm). These dimensions are the interior diameter of the spheres. All spheres and interior platform of the phantom were 3D printed. Each sphere has a shell thickness of 1 mm. The 12 CTN size speres are placed in the same position as that in CTN chest phantom for fair comparison. The lung cavities consists of spongy materials that closely mimicks the lung tissue of density ~0.3 $ \frac{g}{cm^{3} }$. The total volume occupied by the lungs in this phantom is ~6.038 Liter.

As in CTN existing phantom, we made two circuitary paths to fill this phantom volume. The figure 2 below shows the spheres labelling (A, B, … ,P ,Q). Where, I is two 10 mm contiguous spheres and P and Q are overflow containers for two circuit paths. Fluid path 1 has a sphere volume of ~42.5 ml and fills the spheres (B->D->H->J->M->O->Q) and the fluid path 2 has a sphere volume of ~22.5 ml and fills the spheres (C->E->I->L->A->F->G->K->N->P). A total of ~75 ml radioactive solution is needed to fill all the spheres (total volume ~65 ml) and tubing volume (path 1: 48 ml, path 2: 27 ml).

Phantom measurements:

• Dry phantom weight = 3.54 kg
• Phantom fill volume = 22.35 Liter
• Total phantom weight after filling = 25.90 kg

This phantom is currently being inspected at different institutions (University of Iowa, University of Pensylvania, and Royal Prince Alfred Hospital in Australia).