title: A novel method for interactive multi-objective dose-guided patient positioning.
abstract: In intensity-modulated radiation therapy (IMRT), 3D in-room imaging data is typically utilized for accurate patient alignment on the basis of anatomical landmarks. In the presence of non-rigid anatomical changes, it is often not obvious which patient position is most suitable. Thus, dose-guided patient alignment is an interesting approach to use available in-room imaging data for up-to-date dose calculation, aimed at finding the position that yields the optimal dose distribution. This contribution presents the first implementation of dose-guided patient alignment as multi-criteria optimization problem. User-defined clinical objectives are employed for setting up a multi-objective problem. Using pre-calculated dose distributions at a limited number of patient shifts and dose interpolation, a continuous space of Pareto-efficient patient shifts becomes accessible. Pareto sliders facilitate interactive browsing of the possible shifts with real-time dose display to the user. Dose interpolation accuracy is validated and the potential of multi-objective dose-guided positioning demonstrated for three head and neck (H&N) and three prostate cancer patients. Dose-guided positioning is compared to replanning for all cases. A delineated replanning CT served as surrogate for in-room imaging data. Dose interpolation accuracy was high. Using a [Formula: see text] dose difference criterion, a median pass-rate of 95.7% for H&N and 99.6% for prostate cases was determined in a comparison to exact dose calculations. For all patients, dose-guided positioning allowed to find a clinically preferable dose distribution compared to bony anatomy based alignment. For all H&N cases, mean dose to the spared parotid glands was below [Formula: see text] (up to [Formula: see text] with bony alignment) and clinical target volume (CTV) [Formula: see text] above 99.1% (compared to 95.1%). For all prostate patients, CTV [Formula: see text] was above 98.9% (compared to 88.5%) and [Formula: see text] to the rectum below [Formula: see text] (compared to 56.1%). Replanning yielded improved results for the H&N cases. For the prostate cases, differences to dose-guided positioning were minor.
authors.affiliation: Fraunhofer Institute for Industrial Mathematics (ITWM), Kaiserslautern, Germany.
authors.forename: Jonas
authors.initials: J
authors.lastname: Haehnle
authors.forename: Philipp
authors.initials: P
authors.lastname: Süss
authors.forename: Guillaume
authors.initials: G
authors.lastname: Landry
authors.forename: Katrin
authors.initials: K
authors.lastname: Teichert
authors.forename: Lucas
authors.initials: L
authors.lastname: Hille
authors.forename: Jan
authors.initials: J
authors.lastname: Hofmaier
authors.forename: Dimitri
authors.initials: D
authors.lastname: Nowak
authors.forename: Florian
authors.initials: F
authors.lastname: Kamp
authors.forename: Michael
authors.initials: M
authors.lastname: Reiner
authors.forename: Christian
authors.initials: C
authors.lastname: Thieke
authors.forename: Ute
authors.initials: U
authors.lastname: Ganswindt
authors.forename: Claus
authors.initials: C
authors.lastname: Belka
authors.forename: Katia
authors.initials: K
authors.lastname: Parodi
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Küfer
authors.forename: Christopher
authors.initials: C
authors.lastname: Kurz
mesh_terms: D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D008297:Male; D056888:Patient Positioning / Q000379:methods*; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated