Towards patient selection for cranial proton beam therapy – Assessment of current patient-individual treatment decision strategies

Proton beam therapy shows dosimetric advantages in terms of sparing healthy tissue compared to conventional photon radiotherapy. Those patients who are supposed to experience the greatest reduction in side effects should preferably be treated with proton beam therapy. One option for this patient selection is the model-based approach. Its feasibility in patients with intracranial tumours is investigated in this thesis. First, normal tissue complication probability models for early and late side effects were developed and validated in external cohorts based on data of patients treated with proton beam therapy. Acute erythema as well as acute and late alopecia were associated with high-dose parameters of the skin. Late mild hearing loss was related to the mean dose of the ipsilateral cochlea. Second, neurocognitive function as a relevant side effect for brain tumour patients was investigated in detail using subjective and objective measures. It remained largely stable during recurrence-free follow-up until two years after proton beam therapy. Finally, potential toxicity differences were evaluated based on an individual proton and photon treatment plan comparison as well as on models predicting various side effects. Although proton beam therapy was able to achieve a high relative reduction of dose exposure in contralateral organs at risk, the associated reduction of side effect probabilities was less pronounced. Using a model-based selection procedure, the majority of the examined patients would have been eligible for proton beam therapy, mainly due to the predictions of a model on neurocognitive function.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Technische Universität Dresden

Year

2020

Author dc:creator

• Dutz, Almut

Contributors dc:contributor

• Löck, Steffen
• Langendijk, Johannes Albertus

• model-based approach
• proton beam therapy
• brain tumours
• modellbasierter Ansatz
• Protonentherapie
• Hirntumoren