[Physical basics and clinical realization of interstitial brachytherapy of the prostate with iodine 125].
BACKGROUND
Interstitial brachytherapy with I-125 seeds can be used for successful treatment of early stage prostate cancer. There is presented the technique of permanent transperineal implantation of I-125 seeds with intraoperative treatment planning which is suited for the treatment of prostate cancer up to the clinical stage of T2a.


METHODS
Some weeks before the implantation of the seeds the prostate volume is determined using transrectal ultrasound (TRUS) so as to estimate the required number of I-125 seeds. At the outset of the treatment the prostate is stabilized by two perineally inserted needles. Subsequently there is carried out an ultrasound guided treatment planning that allows to optimize the distribution of the seeds within the prostate. In interstitial brachytherapy we use RAPID STRANDS((R)), i. e. the I-125 seeds are embedded in vicryl suture at distances of 1 cm. During implantation of the I-125 seeds the transversal placement of the applicator needles is controlled by TRUS and the cranio-caudal placement of the applicator needles is controlled using the fluoroscopic unit as well as TRUS. About 4 weeks after the implantation of the seeds there is carried out a postoperative computation of the dose distribution of the implant using CT imaging.


RESULTS
The procedure possesses the advantage that ultrasound imaging, treatment planning and seed implantation are carried out with the prostate remaining in an unaltered position. During implantation the combined imaging of TRUS and fluoroscopy allows a safe placement of the seeds with in the prostate.


CONCLUSIONS
The methods for the calculation of the actually attained dose distribution must still be optimized, because the postoperative examination of the individual results has so far been possible only with difficulties resulting from methodological inconveniences.
Kaulich
Theodor W
TW
Abteilung Medizinische Physik, Universitätsklinik für Radioonkologie, Tübingen, Germany. theodor.kaulich@med.uni-tuebingen.de
Lamprecht
Ulf
U
Paulsen
Frank
F
Kahmann
Frank
F
Maurer
Uwe
U
Henkel
Thomas Oliver
TO
Loeser
Wolfgang
W
Bichler
Karl-Horst
KH
Nüsslin
Fridtjof
F
Bamberg
Michael
M
D000368:Aged; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D003198:Computer Simulation; D019160:Endosonography / Q000295:instrumentation; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation; D014057:Tomography, X-Ray Computed
D007457:Iodine Radioisotopes