Development, manufacturing and validation of patient-specific 3D range-modulators for the very fast irradiation of moving tumours in particle therapy

Particle therapy has established clinically in the last decades as it can deliver dose to the target in a highly precise and conformal manner and has been shown to be especially beneficial and effective for certain types of cancer. Its application for moving targets, however, is challenging due to...

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Bibliographic Details
Main Author: Simeonov, Yuri
Contributors: Engenhart-Cabillic, Rita (Prof. Dr.); Zink, Klemens (Prof. Dr.) (Thesis advisor)
Format: Doctoral Thesis
Language:English
Published: Philipps-Universität Marburg 2024
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Summary:Particle therapy has established clinically in the last decades as it can deliver dose to the target in a highly precise and conformal manner and has been shown to be especially beneficial and effective for certain types of cancer. Its application for moving targets, however, is challenging due to the relatively long irradiation time and the resulting “interplay” effects between the scanned beam and the target motion, which lead to dose deterioration. In addition, ultra-high dose rate FLASH irradiation, which is expected to enhance the therapeutic window, cannot be achieved with the conventional active raster scanning method due to the switching time between the single iso-energy layers. This dissertation presents the concept of static range-modulating devices manufactured by rapid prototyping for the very fast dose application with only one fixed energy and a scanned particle beam. The development of 2D range-modulators (RM) is shown and their application is validated in a research project for high-precision water calorimetry. The concept is extended to a 3D range-modulator (3D RM), optimized and customized to a patient-specific target shape. The modulators are manufactured with high-quality 3D printers, different materials and printing techniques. The resulting dose distribution is first validated by simulations and then by fast, completely automated and high resolution measurements using a water phantom system. Overall, an end-to-end process chain is demonstrated, from the RM development to the final dose evaluation. Highly homogeneous dose distributions are achieved with a very good agreement between the predicted and measured data. In the case of the 3D RM, the delivered dose is additionally conformed to both the proximal and distal edge of the target. Most importantly, the modulators manage to deliver the prescribed dose in a fraction of the time required for conventional scanned particle therapy. The presented work demonstrates the feasibility of using 3D-printed 3D range-modulators in particle therapy. The 3D RM concept combines extremely short irradiation times with a high degree of dose conformity and homogeneity, promising clinically applicable dose distributions for lung and/or FLASH treatment, potentially comparable and competitive to those from conventional irradiation techniques.
DOI:10.17192/z2024.0170