  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 datas 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. This
is done in comparison to the standard approach that uses polynomial
interpolation. Moreover, we investigate the effect and the utility of flexible
sensor location on the quality of photoacoustic image reconstruction. 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. We show that with appropriate
sampling the imaging quality can be significantly improved. Reconstructions
with synthetic and real data show the superiority of this method.
