Speaker
Description
Carbon-ion radiotherapy provides superior precision in targeting tumors, while significantly reducing the exposure of surrounding healthy tissue to radiation dose as compared to conventional X-ray radiotherapy. However, the same underlying principle increases the sensitivity of the dose distribution to variations of patient positioning and anatomical changes such as nasal cavity filling or tumor shrinkage. Such changes can result in overdosage of healthy tissue as well as underdosage in the tumor, thereby potentially compromising the treatment outcome.
To mitigate these risks, we are developing a novel, non-invasive in-vivo monitoring technique that uses charged nuclear fragments resulting from nuclear interactions of the carbon ions with the patient’s tissue. These fragments, which are a by-product of the treatment irradiation, are tracked by a self-developed detection system incorporating 28 Timepix3 silicon pixel detectors. By reconstructing and analyzing the spatial distributions of the fragments’ origins, we aim to identify anatomical changes of the patient between treatment sessions. This method is currently tested in the InViMo (In-Vivo Monitoring) clinical trial at the Heidelberg Ion Beam Therapy Center (HIT), focusing on patients with tumors in the skull base region. To facilitate detailed investigations of observed signals, patient specific Monte Carlo simulations of the monitoring method have been implemented.
This contribution demonstrates the clinical potential of the monitoring method on the example of the most recent patient cases from the InViMo clinical trial. Signals in fragment distributions are presented, which can be explained by anatomical changes visible in CT scans taken over the treatment course. These changes result in clinically relevant deviations of the delivered from the planned dose distribution, which can make a treatment-plan adaptation necessary. The signals observed in the measurement data are confirmed by Monte Carlo simulations, which are based on the patients’ CTs. These results represent a significant step toward optimizing carbon-ion radiotherapy by incorporating in-vivo monitoring, which could decrease dose deposition uncertainties and therefore permit dose escalation.
| Workshop topics | Applications |
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