[Iodine-125 transperineal prostate brachytherapy with preplanning technique: pre and post-implant dosimetry results analysis].
OBJECTIVE
Post-implant CT-based dosimetry is the only method of assessing the quality of permanent prostate brachytherapy. As a consequence of our permanent feedback with the preplanned technique, geometric and dosimetric criteria for optimal seed implantation are proposed and pre and post-implantation dosimetric results are presented.


METHODS
In 2000 and 2001, one hundred and twenty patients with early stage prostate cancer were treated with transperineal I-125 preplanned brachytherapy (RAPID Strand, Amersham Health). The prescription dose was 145 Gy to the planning target volume. For the pre-planning and post-implant dosimetry the Variseed 6.7 version software was used (Varian Medical Systems). The D90, V100 and V150 values, the position of the dose peak [Dose] peak) and the full width at half maximum (FWHM) on differential dose volume histogram from both planned and post-implant dosimetry were compared for all patients.


RESULTS
For preplanned dosimetry, the mean values for D90, V100, V150, [Dose] peak, FWMH were respectively of 199Gy, 100%, 70%, 220Gy, 113Gy. For post-implantation, these values became respectively of 157Gy, 90%, 62%, 220Gy, 194Gy.


CONCLUSIONS
In our practice, differences are noted between preplanned and post-implant dosimetry parameters that should be anticipated to assure optimal definitive result. A working methodology both for performing the preplanned dosimetry and for evaluating the post-implantation dosimetric results is proposed.
Simonian-Sauve
M
M
Département de radiothérapie, institut Paoli-Calmettes, 232, boulevard Sainte-Marguerite, BP 156, 13273 cedex 9, Marseille, France.
Smart
C
C
Mailleux
H
H
Rosello
R
R
Bladou
F
F
Salem
N
N
D001918:Brachytherapy / Q000379:methods*; D019583:Dose Fractionation, Radiation; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D012984:Software; D014057:Tomography, X-Ray Computed
D007457:Iodine Radioisotopes
Curiethérapie prostatique transpérinéale par iode 125 avec dosimétrie prévisionnelle: analyse des résultats dosimétriques pré- et post-implantation.