Biomedical subjects

M Simonian-Sauve

Publications and source records attributed to M Simonian-Sauve.

3 recordsLinked to original sources

PubMed2003

[Iodine-125 transperineal prostate brachytherapy with preplanning technique: pre and post-implant dosimetry results analysis].

PURPOSE: 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. PATIENTS AND 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. CONCLUSION: 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.

Brachytherapy↗

PubMed2000

Dose escalation with 3D-CRT in prostate cancer: French study of dose escalation with conformal 3D radiotherapy in prostate cancer-preliminary results.

PURPOSE: To evaluate the feasibility of dose escalation in a multi-institutional study in prostate cancer patients. METHODS AND MATERIALS: Between October 1995 and October 1998, 164 patients with localized adenocarcinoma of the prostate were treated with 3-dimensional conformal radiotherapy at one of five French institutions. The dose of radiation was escalated from 66 to 80 Gy (ICRU point). The maximum dose to the rectal wall was limited to 75 Gy. RESULTS: Results were compared in two groups, one (group 1) receiving the standard dose (n = 46 patients; 66 to 70 Gy) and the other (group 2) receiving the escalated dose (n = 118 patients; 74 to 80 Gy). There was no difference in the characteristics of patients between the two groups. The mean follow-up time was 32 months in group 1 and 17.5 months in group 2. No statistical difference between the two groups was observed in the incidence of late gastrointestinal and urinary toxicities. The probability of achieving a posttreatment prostate-specific antigen nadir of </=1 ng/mL in the 120 patients who did not receive neoadjuvant androgen-deprivation therapy was significantly higher in the dose-escalation group and was directly related to the dose of radiation given. CONCLUSION: This multi-institutional study demonstrated the feasibility of escalating the dose of radiation to 80 Gy in prostate cancer patients.

Adenocarcinoma↗

PubMedDate not supplied

[Evaluation tests of computer systems concerning tri-dimensional dose calculations].

The development of irradiation techniques in radiotherapy shows a clear tendency towards the systematic use of three-dimensional (3D) information. Great efforts are being made to set up 3D conformal radiotherapy. Consequently, in the aim of greater coherence and accuracy, "the dosimetric tool" must also meet the requirements of 3D radiotherapy, as it plays a role in the treatment chain. To know if the treatment planning system is a "3D", "2D" or even "1D" system, one should not be satisfied with reading the technical documentation and the program algorithm description nor entirely trust the constructor's assertions. It is essential to clearly and precisely evaluate the possibilities of the treatment planning system. Even if it is proved not to satisfy perfectly all the tests which would qualify it as a real 3D calculation system, the study of the test results helps to give clear explanations of the dosimetric results. Two series of test cases are proposed. The first series allows us to understand in which conditions the treatment planning system takes into account the scatter influence in a volume. The second series is designed to inform us about the capability of the dose calculation algorithm when the medium encloses non-homogeneities. These test cases do not constitute an exhaustive "check-list" able to tackle completely the question of 3D calculation. They are submitted as examples and should be considered as an evaluation methodology for the software implanted in the treatment planning system.

Computer Simulation↗