Combining rescanning and gating for a time-efficient treatment of mobile tumors using pencil beam scanning proton therapy.

Gut, Pauline; Krieger, Miriam; Lomax, Tony; Weber, Damien C.; Hrbacek, Jan (2021). Combining rescanning and gating for a time-efficient treatment of mobile tumors using pencil beam scanning proton therapy. Radiotherapy and oncology, 160, pp. 82-89. Elsevier 10.1016/j.radonc.2021.03.041

[img]
Preview
Text
1-s2.0-S0167814021061879-main.pdf - Published Version
Available under License Publisher holds Copyright.

Download (1MB) | Preview

BACKGROUND AND PURPOSE

Respiratory motion during proton therapy can severely degrade dose distributions, particularly due to interplay effects when using pencil beam scanning. Combined rescanning and gating treatments for moving tumors mitigates dose degradation, but at the cost of increased treatment delivery time. The objective of this study was to identify the time efficiency of these dose degradation-motion mitigation strategies for different range of motions.

MATERIALS AND METHODS

Seventeen patients with thoracic or abdominal tumors were studied. Tumor motion amplitudes ranged from 2-30 mm. Deliveries using different combinations of rescanning and gating were simulated with a dense dose spot grid (4x4x2.5 mm3) for all patients and a sparse dose spot grid (8x8x5 mm3) for six patients with larger tumor movements (>8 mm). The resulting plans were evaluated in terms of CTV coverage and time efficiency.

RESULTS

Based on the studied patient cohort, it has been shown that for amplitudes up to 5 mm, no motion mitigation is required with a dense spot grid. For amplitudes between 5 and 10 mm, volumetric rescanning should be applied while maintaining a 100% duty cycle when using a dense spot grid. Although gating could be envisaged to reduce the target volume for intermediate motion, it has been shown that the dose to normal tissues would only be reduced marginally. Moreover, the treatment time would increase. Finally, for larger motion amplitudes, both volumetric rescanning and respiratory gating should be applied with both spot grids. In addition, it has been shown that a dense spot grid delivers better CTV dose coverage than a sparse dose grid.

CONCLUSION

Volumetric rescanning and/or respiratory gating can be used in order to effectively and efficiently mitigate dose degradation due to tumor movement.

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:

0167-8140

Publisher:

Elsevier

Language:

English

Submitter:

Beatrice Scheidegger

Date Deposited:

11 May 2021 15:27

Last Modified:

11 May 2021 15:35

Publisher DOI:

10.1016/j.radonc.2021.03.041

PubMed ID:

33839206

Uncontrolled Keywords:

4D proton therapy intrafractional motion pencil beam scanning respiratory gating time efficiency tumor coverage volumetric rescanning

BORIS DOI:

10.48350/155949

URI:

https://boris.unibe.ch/id/eprint/155949

Actions (login required)

Edit item Edit item
Provide Feedback