title: Reproducibility of patient setup in the seated treatment position: A novel treatment chair design.
abstract: Radiotherapy in a seated position may be indicated for patients who are unable to lie on the treatment couch for the duration of treatment, in scenarios where a seated treatment position provides superior anatomical positioning and dose distributions, or for a low-cost system designed using a fixed treatment beam and rotating seated patient. In this study, we report a novel treatment chair that was constructed to allow for three-dimensional imaging and treatment delivery while ensuring robust immobilization, providing reproducibility equivalent to that in the traditional supine position. Five patients undergoing radiation treatment for head-and-neck cancers were enrolled and were setup in the chair, with immobilization devices created, and then imaged with orthogonal X-rays in a scenario that mimicked radiation treatments (without treatment delivery). Six subregions of the acquired images were rigidly registered to evaluate intra- and interfraction displacement and chair construction. Displacements under conditions of simulated image guidance were acquired by first registering one subregion; the residual displacement of other subregions was then measured. Additionally, we administered a patient questionnaire to gain patient feedback and assess comparison to the supine position. Average inter- and intrafraction displacements of all subregions in the seated position were less than 2 and 3 mm, respectively. When image guidance was simulated, L-R and A-P interfraction displacements were reduced by an average of 1 mm, providing setup of comparable quality to supine setups. The enrolled patients, who had no indication for a seated treatment position, reported no preference in the seated or the supine position. The novel chair design provides acceptable inter- and intrafraction displacement, with reproducibility equivalent to that reported for patients in the supine position. Patient feedback will be incorporated in the refinement of the chair, facilitating treatment of head-and-neck cancer in patients who are unable to lie for the duration of treatment or for use in an economical fixed-beam setup.
authors.affiliation: Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|The University of Texas Graduate School of Biomedical Sciences, Houston, TX, USA.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: McCarroll
authors.affiliation: Department of Radiation Oncology, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Beth M
authors.initials: BM
authors.lastname: Beadle
authors.affiliation: Department of Radiation Oncology, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Danna
authors.initials: D
authors.lastname: Fullen
authors.affiliation: Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Balter
authors.affiliation: Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Followill
authors.affiliation: Dipartimento Di Statistica, Informatica, Applicazioni "G.Parenti", University of Florence Viale Morgagni, Florence, Italy.
authors.forename: Francesco C
authors.initials: FC
authors.lastname: Stingo
authors.affiliation: Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Department of Imaging Physics, Division of Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Laurence E
authors.initials: LE
authors.lastname: Court
mesh_terms: D000368:Aged; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007103:Immobilization / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D056888:Patient Positioning / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061106:Radiotherapy Setup Errors / Q000517:prevention & control*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: novel treatment positioning; patient positioning; upright treatment