Microwave transurethral applicator with helix-loaded-dipole-antenna (HLDA) for prostate treatment

Three designs of transurethral applicators have been analysed to find the one that is best able to selectively heat the desired volume of prostate. A helix-loaded-dipole-antenna (HLDA) inserted into a Foley type catheter was found to be the most promising design. A change in the heat deposition pattern of the antenna depending on prostate size is possible by moving the position of the antenna within a Foley catheter. A number of prototypes of HLDA were manufactured and tested to optimize their design. These tests were performed in solid and liquid phantoms and in laboratory animals. Intra-operative measurements of intra-prostatic temperature distribution were also performed. A comparison of the HLDA with other commercially available transurethral applicators and the published data showed that the present design has a higher linear homogeneity coefficient and a better heat deposition in the prostate.