title: Quantification of an external motion surrogate for quality assurance in lung cancer radiation therapy.
abstract: The purpose of this work was to validate the stability of the end exhale position in deep expiration breath hold (DEBH) technique for quality assurance in stereotactic lung tumor radiation therapy. Furthermore, a motion analysis was performed for 20 patients to evaluate breathing periods and baseline drifts based on an external surrogate. This trajectory was detected using stereo infrared (IR) cameras and reflective body markers. The respiratory waveform showed large interpatient differences in the end exhale position during irradiation up to 18.8 mm compared to the global minimum. This position depends significantly on the tumor volume. Also the baseline drifts, which occur mostly in posterior direction, are affected by the tumor size. Breathing periods, which depend mostly on the patient age, were in a range between 2.4 s and 7.0 s. Fifteen out of 20 patients, who showed a reproducible end exhale position with a deviation of less than 5 mm, might benefit from DEBH due to smaller planning target volumes (PTV) compared to free breathing irradiation and hence sparing of healthy tissue. Patients with larger uncertainties should be treated with more complex motion compensation techniques.
authors.affiliation: University Hospital Erlangen, Radiation Oncology, Universitätsstraße 27, 91054 Erlangen, Germany ; Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Faculty of Medicine, Krankenhausstraße 12, 91054 Erlangen, Germany.
authors.forename: Jens
authors.identifier: 0000-0002-1860-1467
authors.initials: J
authors.lastname: Wölfelschneider
authors.affiliation: University Hospital Erlangen, Radiation Oncology, Universitätsstraße 27, 91054 Erlangen, Germany ; Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Faculty of Medicine, Krankenhausstraße 12, 91054 Erlangen, Germany.
authors.forename: Tobias
authors.identifier: 0000-0002-8270-0144
authors.initials: T
authors.lastname: Brandt
authors.affiliation: University Hospital Erlangen, Radiation Oncology, Universitätsstraße 27, 91054 Erlangen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Lettmaier
authors.affiliation: University Hospital Erlangen, Radiation Oncology, Universitätsstraße 27, 91054 Erlangen, Germany ; Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Faculty of Medicine, Krankenhausstraße 12, 91054 Erlangen, Germany.
authors.forename: Rainer
authors.identifier: 0000-0001-8295-7145
authors.initials: R
authors.lastname: Fietkau
authors.affiliation: University Hospital Erlangen, Radiation Oncology, Universitätsstraße 27, 91054 Erlangen, Germany ; Friedrich-Alexander-University Erlangen-Nürnberg (FAU), Faculty of Medicine, Krankenhausstraße 12, 91054 Erlangen, Germany ; GSI-Helmholtz Centre for Heavy Ion Research, Department of Biophysics, Planckstraße 1, 64291 Darmstadt, Germany.
authors.forename: Christoph
authors.identifier: 0000-0002-8539-6600
authors.initials: C
authors.lastname: Bert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy*; D045853:Exhalation; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011785:Quality Assurance, Health Care; D016634:Radiosurgery; D012119:Respiration