1. A thermoacoustic tomographic method for imaging an object, which comprises: thermally exciting the object and causing acoustic waves to emanate from the object; detecting the acoustic waves from the object, caused by the thermal excitation, from different directions of the object using at least one detector; integrating the acoustic waves detected by the detector at least in one direction over a length of at least √{square root over (8)}·d, where d denotes a maximum distance from a point of the object to the detector; and reconstructing an image of the object from the acoustic waves detected by the detector and positional information.