This is one a bit rough, but it has what many call a Chi-Rho on the reverse in the left field. This should probably be called an Iota-Chi, rather than a Chi-Rho, since it looks very little like the Greek Rho and more like an Iota combined with a Chi. On some examples there is a bit of roundness to the top of the Iota, but not enough to call the symbol a Rho. The second picture is another example that has more detail.
Constantine I
A.D. 320
18mm 2.4gm
CONSTANTINVS AVG; Helmeted, cuirassed
VIRTVS-EXERCIT; Standard inscribed VOT/XX with captive seated on ground on either side. Stylized Chi-Rho in left field.
In ex. AQP
RIC VII Aquileia 58