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In polymer gel dosimetry, the spin–spin relaxation rate R2=1/T2, is related to the absorbed dose that is delivered to a gel phantom by high-energy radiation beams. In a two-points method, R2 is calculated from two differently T2-weighted images. In the many-points method, R2 is calculated by fitting the pixel intensities of a set of differently exponentially T2-weighted images. An analysis of the influence of noise on the resulting R2 image may contribute considerably to the enhancement of the accuracy of the dose map. The relation between the noise level in the differently T2-weighted images and the noise level in the R2 image is derived mathematically. This relation is dependent on the actual R2, on the choice of the echo times in the sequences used, and the fitting algorithm. Both a least square fit to the semi-logarithmic T2-relaxation plot and a maximum-likelihood estimation on the T2-relaxation plot were …