  Within the classical emission model, where the emission region is placed
within the broad line region (BLR), flat spectrum radio quasars (FSRQs) were
believed not to emit photons with energies above few tens of GeV because of the
absorption with the optical-UV photons from the BLR. However, photons with
observed energies up to about $300 \, \rm GeV$ have been detected for few
FSRQs, whose most iconic example is PKS 1441+25 at redshift $z = 0.94$. The
most conservative explanation for these observations is that the emission
occurs at distances comparable to the size of the dusty torus. In this case,
absorption of high-energy gamma-ray photons for energies above $200-300 \, {\rm
GeV}$ is dominated by the interaction with infrared radiation emitted by the
torus. We investigate if current observational data about FSRQs in flaring
state can give us information about: (i) the importance of the torus absorption
and (ii) the properties of the torus i.e. its temperature and its geometry. We
find that present data do not arrive at energies where the torus influence is
prominent and as a result it is currently hardly possible to infer torus
properties from observations. However, with dedicated simulations, we
demonstrate that observations with the forthcoming Cherenkov Telescope Array
(CTA) will be able to constrain the torus parameters (temperature and
geometry).
