Anatomical robust optimization to account for nasal cavity filling variation during intensity-modulated proton therapy: a comparison with conventional and adaptive planning strategies.

van de Water, Steven; Albertini, Francesca; Weber, Damien Charles; Heijmen, Ben J M; Hoogeman, Mischa S; Lomax, Antony John (2018). Anatomical robust optimization to account for nasal cavity filling variation during intensity-modulated proton therapy: a comparison with conventional and adaptive planning strategies. Physics in medicine and biology, 63(2), 025020. Institute of Physics Publishing IOP 10.1088/1361-6560/aa9c1c

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The aim of this study is to develop an anatomical robust optimization method for intensity-modulated proton therapy (IMPT) that accounts for interfraction variations in nasal cavity filling, and to compare it with conventional single-field uniform dose (SFUD) optimization and online plan adaptation. We included CT data of five patients with tumors in the sinonasal region. Using the planning CT, we generated for each patient 25 'synthetic' CTs with varying nasal cavity filling. The robust optimization method available in our treatment planning system 'Erasmus-iCycle' was extended to also account for anatomical uncertainties by including (synthetic) CTs with varying patient anatomy as error scenarios in the inverse optimization. For each patient, we generated treatment plans using anatomical robust optimization and, for benchmarking, using SFUD optimization and online plan adaptation. Clinical target volume (CTV) and organ-at-risk (OAR) doses were assessed by recalculating the treatment plans on the synthetic CTs, evaluating dose distributions individually and accumulated over an entire fractionated 50-GyRBE treatment, assuming each synthetic CT to correspond to a 2-GyRBE fraction. Treatment plans were also evaluated using actual repeat CTs. Anatomical robust optimization resulted in adequate CTV doses (V95%≥98% and V107%≤2%) if at least three synthetic CTs were included in addition to the planning CT. These CTV requirements were also fulfilled for online plan adaptation, but not for the SFUD approach, even when applying a margin of 5 mm. Compared with anatomical robust optimization, OAR dose parameters for the accumulated dose distributions were on average 5.9 GyRBE (20%) higher when using SFUD optimization and on average 3.6 GyRBE (18%) lower for online plan adaptation. In conclusion, anatomical robust optimization effectively accounted for changes in nasal cavity filling during IMPT, providing substantially improved CTV and OAR doses compared with conventional SFUD optimization. OAR doses can be further reduced by using online plan adaptation.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Clinic of Radiation Oncology

UniBE Contributor:

Weber, Damien Charles

Subjects:

600 Technology > 610 Medicine & health

ISSN:

0031-9155

Publisher:

Institute of Physics Publishing IOP

Language:

English

Submitter:

Beatrice Scheidegger

Date Deposited:

09 Apr 2018 12:29

Last Modified:

10 Apr 2018 06:32

Publisher DOI:

10.1088/1361-6560/aa9c1c

PubMed ID:

29160775

Uncontrolled Keywords:

IMPT Proton therapy adaptive radiotherapy nasal cavity filling plan adaptation robust optimization sinonasal tumors

BORIS DOI:

10.7892/boris.109260

URI:

https://boris.unibe.ch/id/eprint/109260

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