title: Monitoring proton radiation therapy with in-room PET imaging.
abstract: We used a mobile positron emission tomography (PET) scanner positioned within the proton therapy treatment room to study the feasibility of proton range verification with an in-room, stand-alone PET system, and compared with off-line equivalent studies. Two subjects with adenoid cystic carcinoma were enrolled into a pilot study in which in-room PET scans were acquired in list-mode after a routine fractionated treatment session. The list-mode PET data were reconstructed with different time schemes to generate in-room short, in-room long and off-line equivalent (by skipping coincidences from the first 15 min during the list-mode reconstruction) PET images for comparison in activity distribution patterns. A phantom study was followed to evaluate the accuracy of range verification for different reconstruction time schemes quantitatively. The in-room PET has a higher sensitivity compared to the off-line modality so that the PET acquisition time can be greatly reduced from 30 to <5 min. Features in deep-site, soft-tissue regions were better retained with in-room short PET acquisitions because of the collection of (15)O component and lower biological washout. For soft tissue-equivalent material, the distal fall-off edge of an in-room short acquisition is deeper compared to an off-line equivalent scan, indicating a better coverage of the high-dose end of the beam. In-room PET is a promising low cost, high sensitivity modality for the in vivo verification of proton therapy. Better accuracy in Monte Carlo predictions, especially for biological decay modeling, is necessary.
authors.affiliation: Department of Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Xuping
authors.initials: X
authors.lastname: Zhu
authors.forename: Samuel
authors.initials: S
authors.lastname: España
authors.forename: Juliane
authors.initials: J
authors.lastname: Daartz
authors.forename: Norbert
authors.initials: N
authors.lastname: Liebsch
authors.forename: Jinsong
authors.initials: J
authors.lastname: Ouyang
authors.forename: Harald
authors.initials: H
authors.lastname: Paganetti
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Bortfeld
authors.forename: Georges
authors.initials: G
authors.lastname: El Fakhri
mesh_terms: D003528:Carcinoma, Adenoid Cystic / Q000000981:diagnostic imaging / Q000532:radiotherapy; D005134:Eye Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008875:Middle Aged; D009010:Monte Carlo Method; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000191:economics / Q000379:methods*; D061766:Proton Therapy; D011878:Radiotherapy / Q000379:methods*; D011522:Protons
chemical_list: D011522:Protons