In vivo Quantitative Tomography of 225Ac Daughters in a Prostate Cancer Mouse Model with a Compton Camera
- 1University of California, San Francisco
Abstract
Targeted alpha therapy with 225Ac is a promising modality for cancer treatment, as shown in recent preclinical and clinical studies. Preclinical imaging of 225Ac is essential to fully understand the biokinetics of developmental 225Ac radiopharmaceuticals. Although single photon emission computed tomography (SPECT) is typically used to achieve this in vivo, conventional preclinical scanners struggle to provide high contrast and accurate quantification for 225Ac imaging due to the very low injected activities (below 1 kBq/g), the unfavorable gamma-ray branching ratios (<26%), and its complex decay chain with several gamma-ray emissions. In this work, we employ a compact CZT-based Compton camera to achieve quantitative tomography of 225Ac daughters in live mice at 18.5 kBq (0.5 Ci) injected activities. Three mice bearing 22Rv1 prostate cancer subcutaneous xenografts were scanned in a single bed position for 30 minutes following intravenous administration of 18.5 kBq of the Anti-CD46 225Ac-Macropa-PEG4-YS5 conjugate. We successfully visualized the in vivo biodistributions of the 225Ac daughters 221Fr and 213Bi, distinguishing between the tumor xenograft and the central organs. Quantification of the tumor uptake from the images revealed an activity as low as 1.1 kBq. In vivo activity quantification computed from the images was compared to ex vivo biodistribution measurements using a gamma counter after harvesting the tissue, showing strong agreement.
Related
- Visualization and quantitative analysis of endosperm cavities in maize kernels via X-ray micro-computed tomography
- Mating allows asexual female wasps to produce offspring both sexually and asexually, but their sexual daughters have reduced fecundity
- Toward personalized prostate cancer screening. Information on risk factors and test interpretation for men and healthcare professionals
- In vitro and in silico therapeutic potential of Nyctanthes arbor-tristis (L.) flower extract against prostate cancer
- DNA Methylation and TMPRSS2-ERG Fusion Status in Patients with Prostate Cancer from The Republic of North Macedonia
BibTeX
@misc{das2026vivo,
title = {{In vivo Quantitative Tomography of 225Ac Daughters in a Prostate Cancer Mouse Model with a Compton Camera}},
author = {B. Das and A. P. Bidkar and S. A. Naik and V. Negut and D. Goodman and M. Streicher and J. Lee and O. H. Matousek and R. Heller and M. Basak and B. Liu and Y. Seo and R. R. Flavell and J. Caravaca},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.18.752779},
url = {https://www.biorxiv.org/content/10.64898/2026.09.18.752779v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - In vivo Quantitative Tomography of 225Ac Daughters in a Prostate Cancer Mouse Model with a Compton Camera
AU - B. Das
AU - A. P. Bidkar
AU - S. A. Naik
AU - V. Negut
AU - D. Goodman
AU - M. Streicher
AU - J. Lee
AU - O. H. Matousek
AU - R. Heller
AU - M. Basak
AU - B. Liu
AU - Y. Seo
AU - R. R. Flavell
AU - J. Caravaca
PY - 2026
DA - 2026/09/18
PB - bioRxiv
DO - 10.64898/2026.09.18.752779
UR - https://www.biorxiv.org/content/10.64898/2026.09.18.752779v1
AB - Targeted alpha therapy with 225Ac is a promising modality for cancer treatment, as shown in recent preclinical and clinical studies. Preclinical imaging of 225Ac is essential to fully understand the biokinetics of developmental 225Ac radiopharmaceuticals. Although single photon emission computed tomography (SPECT) is typically used to achieve this in vivo, conventional preclinical scanners struggle to provide high contrast and accurate quantification for 225Ac imaging due to the very low injected activities (below 1 kBq/g), the unfavorable gamma-ray branching ratios (<26%), and its complex decay chain with several gamma-ray emissions. In this work, we employ a compact CZT-based Compton camera to achieve quantitative tomography of 225Ac daughters in live mice at 18.5 kBq (0.5 Ci) injected activities. Three mice bearing 22Rv1 prostate cancer subcutaneous xenografts were scanned in a single bed position for 30 minutes following intravenous administration of 18.5 kBq of the Anti-CD46 225Ac-Macropa-PEG4-YS5 conjugate. We successfully visualized the in vivo biodistributions of the 225Ac daughters 221Fr and 213Bi, distinguishing between the tumor xenograft and the central organs. Quantification of the tumor uptake from the images revealed an activity as low as 1.1 kBq. In vivo activity quantification computed from the images was compared to ex vivo biodistribution measurements using a gamma counter after harvesting the tissue, showing strong agreement.
ER -