$20 Posters

structures hence obtain better quality implants. We thank RadTech for providing us with the Thomson-Nielsen MOSFET detectors used in the study

62 poster Monotherapeutic 3-D CT-gu ided pararectal brachytherapy of prostate cancer with biopsy-proven seminal vesicle invasion: 6-year follow-up P. Koutrouvelis Uro-Radiology Prostate Institute, Brachytherapy Department, 8320 Old Courthouse Road, Suite 150, Vienna VA 22182, United States

Three-dimensional monotherapeutic computed tomography-guided posteri- or pararectal brachytherapy for 3-D CT-guided brachytherapy. Each under- went further staging with 3-D CT-guided brachytherapy. Each underwent further staging with 3-D CT-guided pararectal biopsy of the seminal vesicles under local anesthesia and/or light sedation. Sixty-one (61) patients (13%) were diagnosed with seminal vesicle invasion (T3b NOM0). Seven of the 61 patients were not treated monotherapeutically for their seminal vesicle inva- sion. The prescribed dosage was achieved in all 54 patients in 90-100% of the seminal vesicles and prostate. Prostate specific antigen (PSA) outcome data were available in 46 patients with follow up ranging from 12-72 months (median, 36 months). Decreased PSA levels were stratified into groups based on the presenting Gleason's score and initial PSA. Disease free sur- vival with PSA < 1.0 ng/ml was achieved in the first group (Gleason's score <6 and initial PSA < 20 ng/ml) in 8 out of 8 patients (100%), in the second group (Gleason's = 7 and initial PSA < 20 ng/ml) in 15 of 16 patients (94%), in the third group (Gleason's score = 7 and initial PSA > 20 ng/ml) in 8 out of 11 patients (73%), in the fourth group (Gleason's score >8 and initial PSA < 20 ng/ml) in 4 of 6 patients (66%) and in the fifth group (Gleason's score >8 and initial PSA > 20 ng/ml) in 3 out of 5 patients (60%). 3-D CT-guided monotherapeutic brachytherapy with permanent implant of iodine-125 or palladium-103 seeds delivers substantially increased dosage to the seminal vesicles. Clinical and biochemical results are encouraging in patients with low initial PSA levels and Gleason's scores of 7 or less, but longer-term data in a greater number of patients is necessary.

63 poster Needle displacement in fractionated prostate HDR brachy- therapy A.C. Pellizzon 1,2, J. Salvajoli 1 , M. Maia 1, P. Novaes 1 , R. Ferigno 1, R. Fog- aroli l , 2

1Hospital AC Camargo, Radiation Oncology, Sao Paulo, Brasil 21nstituto Arnaldo vieira de Carvalho, Radiotherapy, Sao Paulo, Brasil

Puroose: To determine the displacement of needles (ND) and its impact in the outcome of initial and locally advanced prostate cancer treated with con- ventional EBRT and fractionated transretal ultrasound guided high dose rate afterloading brachytherapy (HDR-BT) as a boost. Methods and Materials: from 03/97 to 09/99 a total 47 patients were eligibly for study entry. Patients with 1992 AJCC clinical stage T3a or lesser and prostatic volume < 60cc were eligibly. All patients had prior to HDR-BT a course of pelvic localized EBRT, to a median dose of 46Gy (range: 45- 50.4Gy). Results: median age was 68 years (range 47 to 83) and mean follow-up 38 months (range 30 to 48). Treatments were delivered through the micro- Selectron HDR, using Ir192 single stepping source. Minimal or no needle displacement occurred in 17% (8/47) patients. There were 61.7% (29/47) patients who needed one correction and 21.3%(10/47) who needed two cor- rections. There were no correlation with ND (p=0.130) and times of ND (p=0.295) occurrence with bNED. The crude and actuarial biochemical con- trols (bNED) in 48 months for all patients were 87.2% and 82.3% respec- tively. Actuarial bNED in 4-years for patients without and with ND were 75% and 89,7% (p=0.254). Discussion: There are many advantages in HDR-BT, but the most important ones are the capability of on-line dosimetry and quality control. The proce- dure is very conformal, with dose-volume histograms representing the administered dose, but we still need to wait for results of phase III open tri- als that analyses HDR-BT and conformal therapy.

64 poster The permanent implantation of pa l l ad ium-103 seeds in prostate cancer C. Somav. R. OismOIler, R. Hawliczek Institute of Radiooncology, SMZ-Ost, Donauspital, Vienna, Austria

Introduction: because of PSA screening early detection of prostate cancer is increasing rapidly. Additionally functional aspects like potency and uri- nary continency are of growing importance especially for younger patients. Brachytherapy by permanent implants of iodine or palladium seeds are highly curative with very low functional risks and morbidity. Material & methods: between 7/1999 and 8/2001 72 patients with early stage prostate cancer (organ confined, PSA <10, Gleason sum _< 7) were treated with palladium 103 seed implantation at the Institute of Radiation Oncology, SMZ-Ost, Donauspital. The median time of follow up was 12 months. Routinely the preoperative staging included MRT for exclusion of capsular penetration or infiltratioin of seminal vesicals. The applied dose was 115 Gy after the change of international guidelines 2001 dose was raised to 125 Gy. Three weeks after implantation seed distribution and dose distributions were recalculated by CT and MRI imaging. Results: intraoperatively were no complications at all. Mild dysuria was the main side effect in nearly all patients, a minimal proctitis occurred within 3 months after implantation, in just two cases. Two patients died of unrelat- ed reasons during follow-up. PSA follow-up: in 85 % patients PSA value dropped to <lng/ml after 6 months, 74% of remaining patients after 6 months later. These results are very encouraging. PSA nadir is expected two years after implantation. Conclusion: permanent palladium implants in early stage prostate cancer are highly curative with very low morbidity and no mortality. A clear improvement of implant quality was seen with growing experience. Recent data on tumour control, complication rates as well as quality of life will be presented.

65 poster Radiation dose distribution following permanent 1-125 seed prostate brachytherapy I. Aslav 1, G. Kemikler 2, N. Tenekeci 3, I. Ozbay 2, D. Atilgan 4, T. Esen 4, M. Akinci 4, M. Tunc 4, F. Yaman 1, S. Kucucuk 1 llstanbul University Oncology Ir)stitute, Radiation Oncology, Istanbul, Turkey 21stanbul University Oncology Institute, Medical Physics, Istanbul, Turkey 31stanbul University Oncology Institute, Radiology, Istanbul, Turkey 41stanbul Univ. Istanbul Med. School, Urology, Istanbul, Turkey

PurDose: To investigate prostat dose coverage, over and under dosage, as well as the rectal and urethral doses in planned and realized permanent 1- 125 seed prostate implants and to evluate the results of cumulative dose- volume histograms (CDVH) for the data of the first ten patients. Material and methods: Between June 2000 and December 2001, ten patients with T1-2 NO prostate cancer were treated with transrectal ultra- sound guided transperinea1125Iodine seed (RAPID strand) implants at the Istanbul University Oncology Institute. Prescribed minimum peripheral dose was 145 Gy. Median activity was 0.45 (0.43-0.47) U/seed, planned and realized median seed quantities were 75 (57-87) and 84 (66-92). Patients were given corticosteroids were used during postimplant 2 weeks. Preplan- ning volumes obtained from B&K ultrasound (US) and postplanning vol- umes derived from combination of CT scan sliceses which were 3mm in thickness at 0.5mm interval and taken 4-6 weeks after the implants and axial MRI slices which were performed at the same conditions. Delineated prostate, urethra and rectum volumes as well as seeds on CT slices were transferred to the MMS 6.7 software with assistance of image prosesing software.Volumes of the organs and CDVH obtained from the treatment planning system. ResvIt~: There was no seed loss. Pre and post planning median prostate and uretra volumes were 30.21 cc (17.10- 37.92), 31.81 cc (20.17- 39.92), and 0.31 cc (0.21-0.74), 0.69cc (0.48-1.08) respectively. Planned coverage median values for D90, V100, V150 were 172 Gy (163-195), 99% (95-99), 58 % (43-66), and realized ones were 143Gy (125-192), 89.5% (81-96), 64% (39-85) for prostate. Planned and realized V100, V150 for uretra were 100% (75-100), 2%(0-16) and 10.33% (0-30) respectively. V50 and V100 of the rectum were planned to be 4.79 cc (2.18-8.4) and 0.51cc(0.05-2.92)and realized as 3.14cc(1.56-4.62) and 0.84 cc(0-2.44). Conclusions: The difference of planned and realized coverage of doses are due to inadequate coverage of the base of the prostate. It was found to be highly possible that as the needle was being retracted,the seeds were slightly displased by the movement.