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Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
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Longitudinally Heterogeneous Tumor Dose Optimizes Proton Broadbeam, Interlaced Minibeam, and FLASH Therapy
Matthias Sammer1, Aikaterini Rousseti1, Stefanie Girst1
1Faculty of Aerospace Engineering, Institute of Applied Physics and Measurement Technology (LRT 2), Universität der Bundeswehr München, D-85577 Neubiberg, Germany.
Cancers
|October 27, 2022
Summary
Proton minibeam therapy allows for heterogeneous dose distributions, reducing healthy tissue radiation dose and side effects compared to standard proton therapy. This approach offers better tumor control and sparing of healthy tissues, especially in FLASH irradiation modes.
Area of Science:
- Radiation Oncology
- Medical Physics
Background:
- Radiation therapy requires precise dose delivery to tumors while minimizing damage to surrounding healthy tissues.
- Current proton therapy often uses spread-out Bragg peaks (SOBP), but this can lead to dose heterogeneity.
- Proton minibeam therapy offers a novel approach to dose deposition.
Purpose of the Study:
- To compare the effectiveness of different longitudinally heterogeneous proton irradiation modes against standard SOBP.
- To evaluate dose reduction in healthy tissues using proton minibeam therapy.
- To assess the potential for improved tumor control and reduced side effects.
Main Methods:
- Simulated depth-dose curves for three heterogeneous proton irradiation modes and one standard SOBP mode.
- Overlaid symmetric dose distributions from opposing directions in a water phantom with a tumor region.
- Compared interlaced planar minibeam dose distributions with broadbeam distributions.
Main Results:
- All heterogeneous proton irradiation modes demonstrated reduced dose in healthy tissue compared to broadbeam SOBP.
- Proton minibeam irradiation resulted in significantly higher mean cell survival and lower equivalent uniform dose (EUD) in healthy tissue.
- A single proton energy mode showed superior sparing of healthy tissue and better dose fall-off at tumor edges.
Conclusions:
- Longitudinally heterogeneous proton irradiation, particularly minibeam therapy, offers superior healthy tissue sparing compared to standard SOBP.
- This approach is technically feasible and advantageous for ultra-high dose rate (FLASH) proton therapy.
- Proton minibeam therapy holds promise for improving radiation therapy outcomes by enhancing tumor control and reducing side effects.
