Km. Bograchev et Vi. Pasechnik, Estimations of the precision of temperature reconstruction in passive thermoacoustic tomography, ACOUST PHYS, 45(6), 1999, pp. 667-676
Possible characteristics of a passive thermoacoustic tomograph designed for
the reconstruction of a two-dimensional distribution of the internal tempe
rature of an object from its own thermal acoustic radiation in the megahert
z frequency range are estimated by numerical simulation. Two types of Tikho
nov's method of regularization, i.e., the global and the local types, are u
sed to solve the inverse problem. The local type takes into account the phy
sical features of the internal temperature distribution in a human body. It
is demonstrated that, if the rms error of a single measurement is equal to
0.1 K, the average total rms error of the temperature reconstruction is [d
T(R)] approximate to 0.3 K. The utilization of a local regularization provi
des an opportunity to reduce [dT(R)] by 10-15% in many cases. The value of
[dT(R)] weakly depends on the error of a single measurement, and its major
part (approximate to 90%) is determined not by the precision of the physica
l measuring device, but by the algorithms used in the solution of the inver
se problem. The error [dT(R)] relatively weakly depends on the number of re
adings N-H Of the thermodynamic temperature to be determined in the studied
area of the object as well as on the number of measurements N-S > N-H. The
maximum spatial resolution necessary for practical medical tasks is about
6 mm, if the size of the area under investigation is approximate to 10 x 10
cm(2), N-H = 225, and the energy absorption coefficient is gamma 0.2 cm(-1
). This spatial resolution is primarily determined by the thermophysical pr
operties of human tissues.