[Present day development of the Paris System. First part: coplanar patterns and those called "in squares" (author's transl)].

The Paris System is a previsional dosimetric system which facilitates the work of curietherapists working with iridium 192 wires. Introduced about twelve years ago for radio-active implantations in one linear plane, this system has now become more generalized for implantations in two or more linear planes. After a brief review of the principles on which the Paris System is based, and introducing the new definitions arising from its development, the authors present the results of a systematic computerized study. The results obtained were used to establish, among others, the simple relationships between the geometric implantation data (disposition, length, number, separation... of the radioactive lines) and the dimensions of the volume treated, for the coplanar patterns and those called "in squares",