Real-time brachytherapy for prostate cancer: implant analysis

M. Szlag, K. Ślosarek, A. Rembielak, B. Białas, M. Fijałkowski, J. Bystrzycka

Research output: Contribution to journalArticlepeer-review


Background: In HDR brachytherapy precision of catheter implantation is crucial for conformal treatment planning as a starting point for better optimization process.

Aim: The aim was to investigate differences between virtual and real needle position and the effect of needle displacement on dosimetric parameters as a function of prostate volume for better evaluation of "real" implant with respect to final dose distribution.

Materials/Methods: Thirty treatment plans calculated by Nucletron SWIFT™ were randomly selected. Dosimetric data including V100 for prostate gland and D10 for urethra were analyzed as a function of prostate volume and needle displacement. Needle displacement was determined by measuring the distance between virtual and real positions of respective needles in three sectional images: at the base, apex of the prostate gland and reference image. Dosimetric parameters were determined for consecutive computer plans: virtual (before implantation), live (after implantation and renewed optimization). For the purpose of this study a new parameter, VD (Volume-Dose), was created.

Results: VD indicates the quality of "real" dose distribution with respect to "virtual" treatment plan. In order to realize the assumption of virtual plan (VD<1) for a given prostate volume, mean values of needle displacement r should not exceed racceptable according to the formula: racceptable (Vp) ∝ Vp2. For larger glands (above 30cc) final dose distribution is less dependent on needle displacement than smaller ones.

Conclusions: The experiment determined maximum values of needle displacement for a given Vp parameter, allowing one to take advantage of optimization algorithms and to improve the final dose distribution.
Original languageEnglish
Pages (from-to)9-14
Number of pages6
JournalReports of Practical Oncology and Radiotherapy
Issue number1
Publication statusPublished - 29 Feb 2008


  • Interstitial implant
  • Prostate volume
  • Real-time brachytherapy


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