  We address the problem of the electromagnetic radiation produced by charge
distributions in the framework of a semiclassical approach proposed in the work
by Bagrov, Gitman, Shishmarev and Farias [J. Synchrotron Rad. (2020). 27,
902-911]. In this approach, currents, generating the radiation are considered
classically, while the quantum nature of the radiation is kept exactly. Quantum
states of the electromagnetic field are solutions of Schr\"odinger's equation
and relevant quantities to the problem are evaluated with the aid of transition
probabilities. This construction allows us to introduce the quantum transition
time in physical quantities and assess its role in radiation problems by
classical currents. We study radiated electromagnetic energies in detail and
present a definition for the rate at which radiation is emitted from sources.
In calculating the total energy and rate radiated by a pointlike charged
particle accelerated by a constant and uniform electric field, we discover that
our results are compatible with results obtained by other authors in the
framework of the classical radiation theory under an appropriate limit. We also
perform numerical and asymptotic analysis of the results.
