title: Regional MLEM reconstruction strategy for PET-based treatment verification in ion beam radiotherapy.
abstract: In ion beam radiotherapy, PET-based treatment verification provides a consistency check of the delivered treatment with respect to a simulation based on the treatment planning. In this work the region-based MLEM reconstruction algorithm is proposed as a new evaluation strategy in PET-based treatment verification. The comparative evaluation is based on reconstructed PET images in selected regions, which are automatically identified on the expected PET images according to homogeneity in activity values. The strategy was tested on numerical and physical phantoms, simulating mismatches between the planned and measured β+ activity distributions. The region-based MLEM reconstruction was demonstrated to be robust against noise and the sensitivity of the strategy results were comparable to three voxel units, corresponding to 6 mm in numerical phantoms. The robustness of the region-based MLEM evaluation outperformed the voxel-based strategies. The potential of the proposed strategy was also retrospectively assessed on patient data and further clinical validation is envisioned.
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria (DEIB) - Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy. Department of Radiation Oncology-Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.
authors.forename: Chiara
authors.initials: C
authors.lastname: Gianoli
authors.forename: Julia
authors.initials: J
authors.lastname: Bauer
authors.forename: Marco
authors.initials: M
authors.lastname: Riboldi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: De Bernardi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Fattori
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Baselli
authors.forename: Jürgen
authors.initials: J
authors.lastname: Debus
authors.forename: Katia
authors.initials: K
authors.lastname: Parodi
authors.forename: Guido
authors.initials: G
authors.lastname: Baroni
mesh_terms: D000465:Algorithms; D063193:Heavy Ion Radiotherapy; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008113:Liver Neoplasms / Q000532:radiotherapy*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D011879:Radiotherapy Dosage; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies