Deformation of Prostate and Seminal Vesicles Relative to Intraprostatic Fiducial Markers
- Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam (Netherlands)
- Division of Medical Physics, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam (Netherlands)
- Department of Urology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam (Netherlands)
Purpose: To quantify the residual geometric uncertainties after on-line corrections with intraprostatic fiducial markers, this study analyzed the deformation of the prostate and, in particular, the seminal vesicles relative to such markers. Patients and Methods: A planning computed tomography (CT) scan and three repeat CT scans were obtained for 21 prostate cancer patients who had had three to four cylindrical gold markers placed. The prostate and whole seminal vesicles (clinical target volume [CTV]) were delineated on each scan at a slice thickness of 1.5 mm. Rigid body transformations (translation and rotation) mapping the markers onto the planning scan positions were obtained. The translation only (T{sub only}) or both translation and rotation were applied to the delineated CTVs. Next, the residue CTV surface displacements were determined using nonrigid registration of the delineated contours. For translation and rotation of the CTV, the residues represented deformation; for T{sub only}, the residues stemmed from deformation and rotation. T{sub only} represented the residues for most currently applied on-line protocols. The patient and population statistics of the CTV surface displacements were calculated. The intraobserver delineation variation was similarly quantified using repeat delineations for all patients and corrected for. Results: The largest CTV deformations were observed at the anterior and posterior side of the seminal vesicles (population average standard deviation {<=}3 mm). Prostate deformation was small (standard deviation {<=}1 mm). The increase in these deviations when neglecting rotation (T{sub only}) was small. Conclusion: Although prostate deformation with respect to implanted fiducial markers was small, the corresponding deformation of the seminal vesicles was considerable. Adding marker-based rotational corrections to on-line translation corrections provided a limited reduction in the estimated planning margins.
- OSTI ID:
- 21172526
- Journal Information:
- International Journal of Radiation Oncology, Biology and Physics, Vol. 72, Issue 5; Other Information: DOI: 10.1016/j.ijrobp.2008.07.023; PII: S0360-3016(08)03109-X; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dosimetric implications of residual seminal vesicle motion in fiducial-guided intensity-modulated radiotherapy for prostate cancer
Hybrid Registration of Prostate and Seminal Vesicles for Image Guided Radiation Therapy