van de Water, Steven; Safai, Sairos; Schippers, Jacobus M; Weber, Damien C.; Lomax, Antony J (2019). Towards FLASH proton therapy: the impact of treatment planning and machine characteristics on achievable dose rates. Acta oncologica, 58(10), pp. 1463-1469. Taylor & Francis 10.1080/0284186X.2019.1627416
Full text not available from this repository. (Request a copy)This study aimed at evaluating spatially varying instantaneous dose rates for different intensity-modulated proton therapy (IMPT) planning strategies and delivery scenarios, and comparing these with FLASH dose rates (>40 Gy/s). In order to quantify dose rates in three-dimensions, we proposed the 'dose-averaged dose rate' (DADR) metric, defined for each voxel as the dose-weighted mean of the instantaneous dose rates of all spots (i.e., pencil beams). This concept was applied to four head-and-neck cases, each planned with clinical (4 fields) and various spot-reduced IMPT techniques: 'standard' (4 fields), 'arc' (120 fields) and 'arc-shoot-through' (120 fields; 229 MeV only). For all plans, different delivery scenarios were simulated: constant beam intensity, variable beam intensity for a clinical Varian ProBeam system, varied per energy layer or per spot, and theoretical spot-wise variable beam intensity (i.e., no monitor/safety limitations). DADR distributions were calculated assuming 2-Gy or 6-Gy fractions. Spot-reduced plans contained 17-52 times fewer spots than clinical plans, with no deterioration of plan quality. For the clinical plans, the mean DADR in normal tissue for 2-Gy fractionation was 1.7 Gy/s (median over all patients) at maximum, whereas in standard spot-reduced plans it was 0.7, 4.4, 7.1, and 12.1 Gy/s, for the constant, energy-layer-wise, spot-wise, and theoretical spot-wise delivery scenarios, respectively. Similar values were observed for arc plans. Arc-shoot-through planning resulted in DADR values of 3.0, 6.0, 14.1, and 24.4 Gy/s, for the abovementioned scenarios. Hypofractionation (3×) generally resulted in higher dose rates, up to 73.2 Gy/s for arc-shoot-through plans. The DADR was inhomogeneously distributed with highest values at beam entrance and at the Bragg peak. FLASH dose rates were not achieved for conventional planning and clinical spot-scanning machines. As such, increased spot-wise beam intensities, spot-reduced planning, hypofractionation and arc-shoot-through plans were required to achieve FLASH compatible dose rates.
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: |
1651-226X |
Publisher: |
Taylor & Francis |
Language: |
English |
Submitter: |
Beatrice Scheidegger |
Date Deposited: |
07 Aug 2019 15:58 |
Last Modified: |
05 Dec 2022 15:29 |
Publisher DOI: |
10.1080/0284186X.2019.1627416 |
PubMed ID: |
31241377 |
URI: |
https://boris.unibe.ch/id/eprint/131742 |
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