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Research Database PMU-SQQUID

First clinical release of an online, adaptive, aperture-based image-guided radiotherapy strategy in intensity-modulated radiotherapy to correct for inter- and intrafractional rotations of the prostate.
Deutschmann, H; Kametriser, G; Steininger, P; Scherer, P; Schöller, H; Gaisberger, C; Mooslechner, M; Mitterlechner, B; Weichenberger, H; Fastner, G; Wurstbauer, K; Jeschke, S; Forstner, R; Sedlmayer, F;
INT J RADIAT ONCOL. 2012; 83(5): 1624-1632.
Originalarbeiten (Zeitschrift)

PMU-Authors

Deutschmann Heinz
Fastner Gerd
Forstner Rosemarie
Gaisberger Christoph
Jeschke Stephan
Mitterlechner Bernhard
Mooslechner Michaela
Scherer Philipp
Sedlmayer Felix
Steininger Philipp
Wurstbauer Karl

Abstract

PURPOSE
We developed and evaluated a correction strategy for prostate rotations using direct adaptation of segments in intensity-modulated radiotherapy (IMRT).
Implanted fiducials (four gold markers) were used to determine interfractional translations, rotations, and dilations of the prostate. We used hybrid imaging: The markers were automatically detected in two pretreatment planar X-ray projections; their actual position in three-dimensional space was reconstructed from these images at first. The structure set comprising prostate, seminal vesicles, and adjacent rectum wall was transformed accordingly in 6 degrees of freedom. Shapes of IMRT segments were geometrically adapted in a class solution forward-planning approach, derived within seconds on-site and treated immediately. Intrafractional movements were followed in MV electronic portal images captured on the fly.
In 31 of 39 patients, for 833 of 1013 fractions (supine, flat couch, knee support, comfortably full bladder, empty rectum, no intraprostatic marker migrations >2 mm of more than one marker), the online aperture adaptation allowed safe reduction of margins clinical target volume-planning target volume (prostate) down to 5 mm when only interfractional corrections were applied: Dominant L-R rotations were found to be 5.3° (mean of means), standard deviation of means ±4.9°, maximum at 30.7°. Three-dimensional vector translations relative to skin markings were 9.3 ± 4.4 mm (maximum, 23.6 mm). Intrafractional movements in 7.7 ± 1.5 min (maximum, 15.1 min) between kV imaging and last beam"s electronic portal images showed further L-R rotations of 2.5° ± 2.3° (maximum, 26.9°), and three-dimensional vector translations of 3.0 ±3.7 mm (maximum, 10.2 mm). Addressing intrafractional errors could further reduce margins to 3 mm.
We demonstrated the clinical feasibility of an online adaptive image-guided, intensity-modulated prostate protocol on a standard linear accelerator to correct 6 degrees of freedom of internal organ motion, allowing safe and straightforward implementation of margin reduction and dose escalation.


Useful keywords (using NLM MeSH Indexing)

Dose Fractionation

Fiducial Markers

Gold

Humans

Male

Movement*

Prostate/radiography*

Prostatic Neoplasms/radiography*

Prostatic Neoplasms/radiotherapy*

Radiotherapy Planning, Computer-Assisted/methods*

Radiotherapy, Image-Guided/methods*

Radiotherapy, Intensity-Modulated/methods*

Rectum/radiography


Find related publications in this database (Keywords)

Prostate rotations
Gold marker
Adaptive IGRT
Tracking
Open-radART