  To obtain the initial pressure from the collected data on a planar sensor
arrangement in photoacoustic tomography, there exists an exact analytic
frequency domain reconstruction formula. An efficient realization of this
formula needs to cope with the evaluation of the data's Fourier transform on a
non-equispaced mesh. In this paper, we use the non-uniform fast Fourier
transform to handle this issue and show its feasibility in 3D experiments with
real and synthetic data. This is done in comparison to the standard approach
that uses linear, polynomial or nearest neighbor interpolation. Moreover, we
investigate the effect and the utility of flexible sensor location to make
optimal use of a limited number of sensor points. The computational realization
is accomplished by the use of a multi-dimensional non-uniform fast Fourier
algorithm, where non-uniform data sampling is performed both in frequency and
spatial domain. Examples with synthetic and real data show that both approaches
improve image quality.
