TRUS-
and CT-„Image Fusion“ in the Postplanning Procedure after
Transperineal Permanent Interstitial Seedimplantation (TPSI) of “Low
Risk” Prostate Cancer
Block,
T.1; Zimmermann, F.2; Czempiel, H.1
1Urologische Praxis und Medizinphysik Vaterstetten,
2Klinik für Strahlentherapie und Radioonkologie, Technische Universität
München
Introduction:
In the CT-scan it is difficult to determine the prostate volume exactly,
especially in the apical and basal regions. Therefore, the fusion
of CT scans (identification of seeds) with TRUS images (determination
of prostate volume) were examined 30 days after TPSI in order to analyse
the reliability of the postplanning procedure.
Patients/Method:
30 patients (66,9±7,0 years) underwent TPSI (125-I-RAPID Strands®)
because of low risk prostate cancer (cT1-2 Gleason Score <7 iPSA
<10 ng/ml). 30 days after TPSI a CT scan and a TRUS-volumetry (5
mm increments, lithotomy position) were performed. After calibration
CT- and TRUS-images were overlapped (dosimetry-software: PSID 3.5).
During image-fusion the first orientation was carried out at the pubic
arch and further on at the seminal vesicles, special seed locations
and central prostate regions.
CT-/TRUS-Image
Fusion
Results:
Conclusion:
The fusion of CT- and TRUS-images did not lead to a significant change
of prostate volume at day 30 after TPSI. But, however, differences of
D90 and V100 were found in the online- and fusion-planning. This is
due to altered anatomy structures in CT- and TRUS-examination (pressure
of the ultrasound probe on anterior rectal wall). This technique allows
a reliable postplanning procedure after TPSI and is less expensive than
MRT-image fusion.
