[Optimum placement of radiation sources in the planning of interstitial radiotherapy]

The authors compared the results of the designing of interstitial irradiation using the Paris system and the optimum scheme of placing radiation sources. The qualities of formed dose fields were compared by 5 criteria characterizing a dose field at the border, in the center and beyond the target as well as its homogeneity by volume. The correlation showed the advantages of planning using optimal schemes in volumes with an elliptical and irregular section by the criteria of homogeneity of target contour irradiation, the lessening of radiation exposure beyond the target and an increase in the absolute value of minimum dose rate at the border of an irradiated volume.