Respiratory motion-management in stereotactic body radiation therapy for lung cancer - A dosimetric comparison in an anthropomorphic lung phantom (LuCa).
The objective of this study was to compare the latest respiratory motion-management strategies, namely the internal-target-volume (ITV) concept, the mid-ventilation (MidV) principle, respiratory gating and dynamic couch tracking.



An anthropomorphic, deformable and dynamic lung phantom was used for the dosimetric validation of these techniques. Stereotactic treatments were adapted to match the techniques and five distinct respiration patterns, and delivered to the phantom while radiographic film measurements were taken inside the tumor. To report on tumor coverage, these dose distributions were used to calculate mean doses (Dmean), changes in homogeneity indices (ΔH2-98), gamma agreement, and areas covered by the planned minimum dose (A>Dmin).



All techniques achieved good tumor coverage (A>Dmin>99.0%) and minor changes in Dmean(±3.2%). Gating and tracking strategies showed superior results in gamma agreement and ΔH2-98compared to ITV and MidV concepts, which seem to be more influenced by the interplay and the gradient effect. For lung, heart and spinal cord, significant dose differences between the four techniques were found (p<0.05), with lowest doses for gating and tracking strategies.



Active motion-management techniques, such as gating or tracking, showed superior tumor dose coverage and better organ dose sparing than the passive techniques based on tumor margins.
Department of Radiation Oncology, University Hospital Zurich (USZ), Switzerland; University of Zurich, Switzerland. Electronic address: stefanie.ehrbar@usz.ch.
Stefanie
S
Ehrbar
Center for Proton Therapy, Paul Scherrer Institute (PSI), Switzerland.
Rosalind
R
Perrin
Center for Proton Therapy, Paul Scherrer Institute (PSI), Switzerland.
Marta
M
Peroni
Center for Proton Therapy, Paul Scherrer Institute (PSI), Switzerland.
Kinga
K
Bernatowicz
Innovative Design, Centre Suisse d'Electronique et de Microtechnique (CSEM) S. A., Switzerland.
Thomas
T
Parkel
Department of Radiation Oncology, University Hospital Zurich (USZ), Switzerland; University of Zurich, Switzerland.
Izabela
I
Pytko
Department of Radiation Oncology, University Hospital Zurich (USZ), Switzerland; University of Zurich, Switzerland.
Stephan
S
Klöck
Department of Radiation Oncology, University Hospital Zurich (USZ), Switzerland; University of Zurich, Switzerland.
Matthias
M
Guckenberger
Department of Radiation Oncology, University Hospital Zurich (USZ), Switzerland; University of Zurich, Switzerland.
Stephanie
S
Tanadini-Lang
University of Zurich, Switzerland; Center for Proton Therapy, Paul Scherrer Institute (PSI), Switzerland.
Damien Charles
DC
Weber
Center for Proton Therapy, Paul Scherrer Institute (PSI), Switzerland; Swiss Federal Institute of Technology in Zurich (ETHZ), Switzerland.
Antony
A
Lomax
D000886:Anthropometry / Q000379:methods; D056973:Four-Dimensional Computed Tomography / Q000379:methods; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D009068:Movement / Q000502:physiology; D059351:Organ Sparing Treatments / Q000379:methods; D058958:Organs at Risk / Q000528:radiation effects; D019047:Phantoms, Imaging; D011874:Radiometry / Q000379:methods; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012119:Respiration
Couch tracking; Lung phantom; Radiotherapy; Respiratory motion management; Stereotactic body radiation therapy