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Treatment simulations with a statistical deformable motion model to evaluate margins for multiple targets in radiotherapy for high-risk prostate cancer.
- Source :
-
Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology [Radiother Oncol] 2013 Dec; Vol. 109 (3), pp. 344-9. Date of Electronic Publication: 2013 Oct 31. - Publication Year :
- 2013
-
Abstract
- Background and Purpose: Deformation and correlated target motion remain challenges for margin recipes in radiotherapy (RT). This study presents a statistical deformable motion model for multiple targets and applies it to margin evaluations for locally advanced prostate cancer i.e. RT of the prostate (CTV-p), seminal vesicles (CTV-sv) and pelvic lymph nodes (CTV-ln).<br />Material and Methods: The 19 patients included in this study, all had 7-10 repeat CT-scans available that were rigidly aligned with the planning CT-scan using intra-prostatic implanted markers, followed by deformable registrations. The displacement vectors from the deformable registrations were used to create patient-specific statistical motion models. The models were applied in treatment simulations to determine probabilities for adequate target coverage, e.g. by establishing distributions of the accumulated dose to 99% of the target volumes (D99) for various CTV-PTV expansions in the planning-CTs.<br />Results: The method allowed for estimation of the expected accumulated dose and its variance of different DVH parameters for each patient. Simulations of inter-fractional motion resulted in 7, 10, and 18 patients with an average D99 >95% of the prescribed dose for CTV-p expansions of 3mm, 4mm and 5mm, respectively. For CTV-sv and CTV-ln, expansions of 3mm, 5mm and 7 mm resulted in 1, 11 and 15 vs. 8, 18 and 18 patients respectively with an average D99 >95% of the prescription.<br />Conclusions: Treatment simulations of target motion revealed large individual differences in accumulated dose mainly for CTV-sv, demanding the largest margins whereas those required for CTV-p and CTV-ln were comparable.<br /> (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)
- Subjects :
- Humans
Male
Models, Statistical
Motion
Pelvis diagnostic imaging
Prostatic Neoplasms diagnostic imaging
Prostatic Neoplasms pathology
Radiation Protection
Seminal Vesicles diagnostic imaging
Tomography, X-Ray Computed methods
Prostatic Neoplasms radiotherapy
Radiotherapy Planning, Computer-Assisted methods
Subjects
Details
- Language :
- English
- ISSN :
- 1879-0887
- Volume :
- 109
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology
- Publication Type :
- Academic Journal
- Accession number :
- 24183863
- Full Text :
- https://doi.org/10.1016/j.radonc.2013.09.012