Conclusion

We describe a prioritized optimization method to reoptimize IMPT plans in terms of their LET distributions while limiting the degradation of the best possible physical dose distribution. The method does not depend on tissue or patient-specific RBE, which currently is associated with large uncertainties. It can be applied to patients in whom serial critical structures are located within or adjacent to the target volume, to avoid high LET values in these structures. This makes the use of IMPT safer, considering that the risk of side effects associated with high LET is largely unknown.

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Chapter 6

Results III: Lung planning

In section6.2of this chapter, the following publication is reproduced:

P Botas, C Grassberger, G Sharp, and H Paganetti. “Density overwrites of internal tumor volumes in intensity modulated proton therapy plans for mobile lung tumors”. In: Physics in Medicine & Biology63.3 (2018), p. 035023. My role in the publication is clearly stated in the following subsection. Some comments on the adaptation of the publication are also given.

6.1

Role in study

I was the main author in this study, writing all required software and performing the analysis. This includes:

• Creation of the patient’s planning CTs with the ITV density overwrites. • Implementation of the dose delivery time structure from the cyclotron.

• Development of the 4D framework to connect the DIR software, Plastimatch [Sha12], with the dose delivery time structure model and gPMC.

• Plastimatch development to support multiplication and maximum image filters from ITK (Insight Segmentation and Registration Toolkit).

• Results analysis scripts, mainly written in R using the tidyverse libraries (https://www.

tidyverse.org/).

• Manuscript writing.

Comments on the adaptation of the paper: The position of figures and tables may differ from the published manuscript. The citation style and the internal figure, table and equation numbers have been altered, but the underlying meaning has been conserved.