
==== Front
Neurooncol Adv
Neurooncol Adv
noa
Neuro-Oncology Advances
2632-2498
Oxford University Press US

10.1093/noajnl/vdae090.115
vdae090.115
Final Category: Research Methods and Trial Design Considerations
AcademicSubjects/MED00300
AcademicSubjects/MED00310
RMTD-08 RADIATION ABSORBED DOSE TO SPINAL CORD: THERAPY OF LEPTOMENINGEAL METASTASES USING BETA-EMISSION RADIOPHARMACEUTICALS
Bao Ande Case Western Reserve University, Cleveland/OH, USA

Zhao Xia Case Western Reserve University, Cleveland/OH, USA

Phillips William UT Health San Antonio, San Antonio/TX, USA

Brenner Andrew UT Health San Antonio, San Antonio/TX, USA

Youssef Michael UT Southwestern, Dallas/TX, USA

Kumthekar Priya Northwestern, Chicago/IL, USA

Yang Jonathan University of Washington, Seattle/WA, USA

Zheng Yiran Case Western Reserve University, Cleveland/OH, USA

Spratt Daniel E Case Western Reserve University, Cleveland/OH, USA

Moore Melissa Plus Therapeutics, Austin/TX, USA

Hedrick Marc Plus Therapeutics, Austin/TX, USA

LaFrance Norman Plus Therapeutics, Austin/TX, USA

Juverdianu Leonardo Plus Therapeutics, Austin/TX, USA

Blouw Barbara Plus Therapeutics, Austin/TX, USA

8 2024
02 8 2024
02 8 2024
6 Suppl 1 2024 SNO/ASCO CNS Metastases Conference i35i35
© The Author(s) 2024. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

Abstract

BACKGROUND

Over 100,000 cancer patients develop leptomeningeal metastases (LM) annually in the US. LM prognosis is poor with limited treatment options. Beta-emission radiopharmaceuticals, for example, 186Re-nanoliposomes (Rhenium (186Re) Obisbemeda, 186RNL), are a promising new therapeutic approach to deliver high doses of ionizing radiation to the disease without significant normal tissue exposure. However, the dose and possible toxicity to the spinal cord may be a concern. Herein, we report radiation dosimetry to understand the radiation absorbed dose to spinal cord for this novel treatment approach.

METHODS

The T2-weighted MRI of the cervical spine from a patient with LM was segmented into volumes of the cerebrospinal fluid (CSF) and spinal cord. The radiation absorbed dose distribution in CSF and spinal cord were calculated using dose voxel kernel and 3D convolution. The beta-emission radionuclides with different beta-energies (177Lu, 131I, 186Re, 188Re, and 90Y) were calculated. The dose distribution in CSF and spinal cord were summarized and evaluated.

RESULTS

It was found that the radiation absorbed doses to spinal cord are associated with the beta-energy of radionuclides. The mean doses to the spinal cord in the calculated volume were 2.75%, 7.25%, 10.89%, 29.69%, and 37.66% of mean doses in CSF for 177Lu, 131I, 186Re, 188Re, and 90Y, respectively. The radionuclides with lower beta-energy can largely spare the spinal cord with significantly lower radiation doses. The radionuclides with higher beta-energy provide larger doses to spinal cord, while the dose to CSF were more heterogeneous.

CONCLUSION

This radiation dosimetry study demonstrates that beta-emission radiopharmaceuticals with lower beta-energies are optimal for the treatment of LM to maximize the therapeutic ratio given the proximity of the spinal cord. This study provides the guidance for the possible doses to be applied for the safe treatment of LM, including the treatment of patients with previous external beam radiation therapy.
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