Can we compare systems for interstitial therapy?

Three main dosimetry systems are used for interstitial brachytherapy: Manchester, Quimby and Paris Systems. A comparison is made of the rules of source distributions recommended by the three systems stating the advantages and disadvantages of each system. The comparison shows up the differences in the size of the treated volumes for similar implanted volumes. The next sections emphasize the differences in dose specification which make very difficult any comparison of clinical resuults obtained with different systems. Furthermore, the recent development of computers has lead some radiotherapists to specify the dose individually for each patient without reference to any published system. Very large variations in the dose delivered to a patient for a given implant and for the same prescribed dose, may result from this subjective procedure. In the last section one considers the various quality criteria proposed in the literature. 18 refs.; 7 figs