ESTRO 2023 - Abstract Book

S1853

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ESTRO 2023

Results The T1 relaxation rate was fit to a line (Figure 2). The T1 relaxation rate of the material in a 21% oxygen environment at 37C extracted from the fit was 8.17x10-4 [8.08-8.28x10-4] mS-1. With a slope of 7.19x10-6 [6.96-7.41x10-6] mS-1/%02.

Conclusion The silicone material offers the ability to manufacture passive implantable oxygen sensors that can be read out by MR scans. Deployed in brachytherapy needles or fiducial markers, this material provides the ability to measure the spatial and temporal variation of tumor oxygen levels which could inform adaptive treatment planning and monitoring patient response. Future work will determine the optimal material composition to achieve the needed SNR for measurements while maintaining the physical characteristics needed for an implantable device. Implantable MR based oxygen sensors (Figure 1 insert, blue and red silicone compared to brachytherapy seeds and spacers) may provide a means to customize radiation dose plans based on measurements of tumor hypoxia.

PO-2074 Calibration of ADC values for Quantitative MRI

B. Aylward 1 , J. McLean 2

1 NHS Greater Glasgow and Clyde, Department of Clinical Physics and Bioengineering , Glasgow, United Kingdom; 2 NHS Greater Glasgow and Clyde , Department of Clinical Physics and Bioengineering , Glasgow, United Kingdom Purpose or Objective Changes in apparent diffusion coefficient (ADC) have been shown to enable diagnosis, monitor disease, and predict treatment outcomes. However, poor standardisation limits clinical use. The objective of this research was to assess the conformance of a 1.5T MR-Simulator to the Quantitative Imaging Biomarkers Alliance (QIBA) diffusion-weighted imaging (DWI) profile, to confirm that high-quality ADC measurements can be delivered.

ADC values are temperature dependent, therefore, the QIBA DWI profile requires phantom measurements to be made at