Print this page

Evaluation of a Bifocal Reflector on a Clinical Lithotripter

Achim M.Loske PhD, Frenando E.Prieto PhD, Jorge Gutierrez MD, Horacio Zendeja BVS, Alberto Saita MD, Esequiel.Velez Gomez MD
Source: Journal of Endourology Volume: 18 Number: 1 Page: 7 -- 16
Achim M.Loske PhD, Frenando E.Prieto PhD, Jorge Gutierrez MD, Horacio Zendeja BVS, Alberto Saita MD, Esequiel.Velez Gomez MD

DOI: 10.1089/089277904322836596

Publisher: Mary Ann Liebert, Inc.


Abstract

Journal of EndoUrology Volume 18 Number 1

Purpose: To perform in vitro and in vivo tests using a clinical lithotripter in order to determine whether a bifocal reflector is more efficient and produces the same or less tissue damage than a conventional ellipsoidal reflector for electrohydraulic lithotripters. Materials and Methods: A standard ellipsoidal and a novel bifocal reflector were tested on a Tripter Compact lithotripter (Direx Medical Systems, Petach Tikva, Israel). The bifocal reflector was constructed by joining two sectors of two rotationally symmetrical ellipsoidal reflectors having different distances between their foci. The F1 foci of the sectors coincided, creating a separation between the F2 foci. The fragmentation efficiency of the reflectors was compared using kidney-stone models. Shockwave-induced trauma was evaluated in vivo by treating both kidneys of six healthy dogs. One kidney was exposed to shockwaves generated with the conventional reflector, and the other kidney was treated using the bifocal reflector. Pressure measurements were obtained for both reflectors using needle hydrophones.

Results

The new design appeared to be more efficient than the conventional reflector in breaking up kidney-stone models. Tissue damage did not increase when using the bifocal reflector.

Conclusion

The use of bifocal, instead of standard ellipsoidal, reflectors should be considered as an alternative to improve extracorporeal shockwave lithotripsy.