English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Background  Intrahepatic dosimetry is paramount to optimize radioembolization treatment accuracy using radioactive holmium-166 microspheres ( 166 Ho). This requires a practical protocol that combines quantitative imaging of microsphere distribution with automated and robust delineation of the volumes of interest. To this end, we propose a dual isotope single photon emission computed tomography (SPECT) protocol based on  166 Ho therapeutic microspheres and technetium-99 m ( 99m Tc) stannous phytate, which accumulates in healthy liver tissue. This protocol may allow accurate and automatic estimation of tumor-absorbed dose and healthy liver-absorbed dose. The current study focuses on a Monte Carlo-based reconstruction framework that inherently corrects for scatter crosstalk between the  166 Ho and  99m Tc imaging. To demonstrate the feasibility of the method, it is evaluated with realistic phantom experiments and patient data.    Methods  The Utrecht Monte Carlo System (UMCS) was extended to include detailed modeling of crosstalk interactions between  99m Tc and  166 Ho. First,  99m Tc images were reconstructed including energy window-based corrections for  166 Ho downscatter. Next,  99m Tc downscatter in the 81-keV  166 Ho window was Monte Carlo simulated to allow quantitative reconstruction of the  166 Ho images. The accuracy of the  99m Tc-downscatter modeling was evaluated by comparing measurements with simulations. In addition, the ratio between  99m Tc and  166 Ho yielding the best  166 Ho dose estimates was established and the quantitative accuracy was reported.    Results  Given the same level of activity,  99m Tc contributes twice as many counts to the 81-keV window than  166 Ho, and four times as many counts to the 140-keV window, applying a  166 Ho/ 99m Tc ratio of 5:1 yielded a high accuracy in both  166 Ho and  99m Tc reconstruction. Phantom experiments revealed that the accuracy of quantitative  166 Ho activity recovery was reduced by 10% due to the presence of  99m Tc. Twenty iterations (8 subsets) of the SPECT/CT reconstructions were considered feasible for clinical practice. Applicability of the proposed protocol was shown in a proof-of-concept case.    Conclusion  A novel  166 Ho/ 99m Tc dual-isotope protocol for automatic dosimetry compensates accurately for downscatter and allows for the addition of  99m Tc without compromising  166 Ho SPECT image quality.

Simultaneous 166Ho/99mTc dual-isotope SPECT with Monte Carlo-based downscatter correction for automatic liver dosimetry in radioembolization