[Dose-volume histograms for optimization of radiotherapy planning based on the example of esophageal carcinoma].

PURPOSE: The tissue tolerance of a small radiation dose to a large tissue volume applied in small fractions is expected to be different from the tolerance of a high dose to a small volume given in large fractions. Corresponding criteria for judgment have to be worked out.

METHODS

Using the example of oesophagus carcinoma, dose-volume histograms for diverse treatment techniques are calculated and judged by means of multiplanar isodose representations.

RESULTS

The selected treatment plans are ranked with the aid of the dose-volume histograms. We distinguish the tissue inside and outside of the target volume.

CONCLUSIONS

The description of the spatial dose distribution in dependence of the different volumes and the respective fractions of the tumor dose therein with the help of dose-volume histograms brings about a correlation between the physical parameters and the biological effects. In addition one has to bear in mind the consequences of measures that influence the reaction and the side-effects of radiotherapy (e.g. chemotherapy), i.e. the recuperation of the tissues that were irradiated intentionally or inevitably. Taking all that into account it is evident that the dose-volume histograms are a powerful tool for assessing the quality of treatment plans.